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The Indian Roads Congress
E-mail: [email protected]/[email protected]
Founded : December 1934
IRC Website: www.irc.org.in
Volume 42
Number 10October 2014
Contents
ISSN 0376-7256
Page
2
3
5
From the Editor’s Desk - Towards Sustainable
Action Plan for Safety of Road Users
Important Announcement Regarding International
Conference of IRC
Meet the New Secretary General
Page
13
Advertisements
Technical Papers
Shrinkage and Cracking Behavior of Cement Stabilized
Material in Flexible Pavement - A Critical Review
by
ICT Pvt. Ltd.
- Inside Front Cover
Synteen & Lueckenhaus India Pvt. Ltd. - Inside Back Cover
Bentley Systems Pvt. Ltd.
- Outside Back
Cover
4
SA Infrastructure Consultants Pvt. Ltd.
4
Advertisement Tariff
6
BASF
7
Sachi Geosynthetics Pvt. Ltd.
8
Metal Engineering & Treatment Co. Pvt. Ltd.
9
Hindustan Petroleum Corporation Ltd. (Hincol)
10
MeadWestvaco India Pvt. Ltd.
11
Kraton Polymers
12
Tiki Tar
18
Techfab India
22
Spectrum Chemicals
44-61 Amendment/Errata to IRC:6-2014, IRC:112-2011,
IRC:81-1997 and IRC:37-2012
62-65 Circular Issued by MoRT&H
66
Just Published Publications
66
Announcement
67
Arun Soil Lab Pvt. Ltd.
67
Redecon (India) Pvt. Ltd.
68
Gloster Ltd.
69
Tender Notice, NH Allahabad
70
Tender Notice, NH Kanpur
71
Tender Notice, NH Allahabad
72
SMEC
Jamnagar House, Shahjahan Road,
New Delhi - 110 011
Tel : Secretary General: +91 (11) 2338 6486
Sectt. : (11) 2338 5395, 2338 7140, 2338 4543, 2338 6274
Fax : +91 (11) 2338 1649
19
Rheological
Bitumen
by
23
P.K. Ashish
Mohammed
Sadeque
Properties
&
of
Dr. Devesh Tiwari
Nanoclay
Modified
Dr. K.A. Patil
Mix Design of Bituminous Concrete by Bailey
Method
by Swapan
Kumar
Bagui
29
Dr. V.G. Havanagi &
&
Sutanu Bhadra
Subgrade Characteristics of Sand-Fly Ash-Lime
Composite
by R.K. Sharma
35
Failure of Bridge Due to Inadequate Hydraulic
Investigations
by Dr. C.V. Kand
&
Yogita Gupta
Kama Koti Marg, Sector 6, R.K. Puram
New Delhi - 110 022
Tel : Secretary General : +91 (11) 2618 5303
Sectt. : (11) 2618 5273, 2617 1548, 2671 6778,
2618 5315, 2618 5319, Fax : +91 (11) 2618 3669
No part of this publication may be reproduced by any means without prior written permission from the Secretary General, IRC.
Edited and Published by Shri S.S. Nahar on behalf of the Indian Roads Congress (IRC), New Delhi. The responsibility of the contents and the
opinions expressed in Indian Highways is exclusively of the author/s concerned. IRC and the Editor disclaim responsibility and liability for any
statement or opinion, originality of contents and of any copyright violations by the authors. The opinions expressed in the papers and contents
published in the Indian Highways do not necessarily represent the views of the Editor or IRC.
Cover page design: Er. Rakesh Kain
From the Editor’s Desk
Towards Sustainable Action Plan for Safety of Road Users
Dear Stakeholders,
Road is a ‘public asset’ and every individual is a stakeholder. Road users’ perceptual degree of observance
of self discipline is one of the paramount factors which contributes to the extent of severity of road accident.
Nearly 80 percent of roads accidents are attributed to the human error of momentary judgement (primarily
drivers and occasionally vulnerable road users i.e. pedestrians, cyclist, rickshaw/cart pullers) which is observed
to be directly proportional to the degree of mental stress/anxiety of the road user. The primary human error of
omission/commission is observed to be over speeding. Overloading, an economic constraint and deficient road
geometry, mainly lack of setback/sight distance are among the other reasons causing accidents. In our country, over
70 percent victims of road casualty are venerable roads users.
The alarming rate of road accidents in India, not only causing nearing 1.4 lakh deaths every year but also costing
to public exchequer nearly what we are spending annually on education.
The traffic scenario in India is unique and a cause of serious concern. The vast variance in geographical and socioeconomic conditions (results perceptual variance); disproportionality of growth of human/vehicle population density
and pace of road development (increasing traffic congestion); mixed nature of slow; fast and non-mechanized/
pedestrians traffic; limited resources to maintain sustainably essential road safety furniture are the state specific
constraints which restrict us to replicate and adapt the best practices being followed by the developed world.
For user point of view, road traffic can be divided into two categories (i) urban traffic and (ii) country side
(non-urban) traffic. About two thirds of the road accidents occur on non-urban roads. The responsibility for
development & maintenance and traffic management of roads within urban limits is within the domain of State
Governments/Local Municipal Bodies, whereas the responsibility for development & maintenance and sustainability
of free flow of traffic of non-urban NH stretches falls on the Central Government.
It is regretful that in India, there are hardly any emphasis on research/studies to assess the behavioural aspect of
different categories of road users, especially the vulnerable road users.
Realizing the fact that more than 90 percent loss of lives in road accidents occur in developing world which has less
than half of the world’s vehicles, the UN has declared a ‘Decade of Action for Road Safety 2011-2020’.
Hon’ble Supreme Court of India taking into cognizance the state of affairs on the traffic scenario, in the matter
of a civil (writ) petition in its judgement dated 22.04.2014 has constituted a three-member committee under the
chairmanship of Hon’ble Mr. Justice K.S. Radhakrishnan, Supreme Court of India to monitor the progress in the
matter and directed the Government of India to expedite the necessary amendments by legislature in its “collective
wisdom”.
As a landmark initiative to provide emergency assistance to the accident victims during “Golden Hour” (within
first 48 hours), the Government of India has already taken up a scheme of cashless treatment for accident victim(s)
in the empanelled hospital (including trauma centers/super speciality hospitals) on (i) Gurgaon-Jaipur, NH-8 (ii)
Vadodara-Mumbai, NH-8 and (iii) Ranchi-Mahulia, NH-33 sectors. A helpline, Toll free No.1033 is activated.
Under the scheme, Emergency Medical Ambulances Service (EMAS) @ 20 km equipped with advance life support
and fitted with GPS device and control room is provided by the insurance company. Further, in comprehensive
overhauling of MV Act, the Government has drafted MV (Amendment) Bill, 2014 and put in public domain for
suggestions (www.morth.nic.in).
In order to take into cognizance the best practices in the world and to pool our collective wisdom, the IRC is
organising an International Conference on “Road Safety Scenario in India and Way Forward” at Vigyan Bhavan,
New Delhi on 29-30 November, 2014.
I would like to appeal to all our fraternity to join in this event and endeavour and to share their experience and
wisdom in this noble cause of saving avoidable loss of lives and injury due to road accidents and identify an
implementable and sustainable Road Safety Action Plan.
S.S. Nahar
Place :
New Delhi
Secretary General
Dated :
25th September, 2014
Email : [email protected]
2
INDIAN HIGHWAYS, October 2014
Important ANNOUNCEMENT
ReScheduling of International Conference
International Conference on “Road Safety Scenario in India and Way Forward”
will now be held on 29 and 30 November, 2014 (Saturday and Sunday)
at Vigyan Bhawan, New Delhi
Organizers :
Indian Roads Congress (IRC),
Organizing Partners : World Road Association (Piarc)
Japan International Co-operation Agency (JICA)
International Road Federation
The World Bank (Global Road Safety Facility) and
Asian Development Bank (ADB)
Who should attend : Govt./PSU/Autonomous Organization/NGO's/Emergency Medical Service
Providers/Insurance Companies/Automobile Manufacturers/Traffic Police/Law Enforcing Agency/
Research & Academic Institutions/Transporter/Cargo Movers/Fleet Operators/Device Manufacturers,
including all Individuals/Corporators directly or indirectly associated with the Cause of Road Safety.
Tentative Themes of the Conference :
Session 1:
Session 2:
Session 3:
Session 4:
Session 5:
Session 6:
Overview of Traffic Rules & Regulations: Best Practices in the World (UK, Japan)
Road Safety Audit: Best Practices in the World
Overview of Urban & Non-Urban Traffic: Sustainable Way of Traffic Management
including Medical Aid
Overview of Road Users’ Behaviour: Innovative Methods for Mass Awareness
Movement
Review of Design of Vehicles : Innovative & Environmental Friendly Techniques
Panel Discussion & Suggested Way Forward – Short/Long Term.
● For submitting Papers along with brief CV (Words limit 2000 only) (Maximum two papers by
an individual) : Latest by 20th October, 2014 (Monday)
Focal Point: Shri Rahul V. Patil, Deputy Director (Technical), IRC (E-mail: [email protected] &
[email protected]) Tel. 011 – 2671 6778.
● Opportunity available for Advertisers
● Opportunity available for Sponsorship
● Opportunity available for Registration
For further details and enquiry for getting associated with the International Conference, please
contact on E-mail: [email protected], Tel. No.: 2617 1548 and E-mail: [email protected],
Tel. No.: 2338 7140.
INDIAN HIGHWAYS, October 2014
3
INDIAN ROADS CONGRESS, NEW DELHI
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4
INDIAN HIGHWAYS, October 2014
Meet the New Seceretary General
Shri S.S. Nahar
Secretary General
Shri Sajjan Singh Nahar born (Late Maa Joginder Kaur)
on 30th October, 1959 inherited the quality of struggle
being son of an Army man (Shri Darshan Singh) hailed
from Amritsar District (Punjab). Being second to none
in school days with the support and blessing of parents
and teachers he opted for non-medical science stream
and graduated (Civil Engineering) with distinctions in
soil mechanics and structural engineering from MBM
Engineering College, Jodhpur in 1982.
As an admirer of the 1971 war Hero Flying Officer
Nirmal Jit Singh Sekhon, PVC, passed Pilot Aptitude
and Battery Test (PABT) but could not pursue due to
age bar (21 year with graduation).
He started his career in 1983 as Assistant Professor
in Faculty of Engineering, University of Jodhpur and
pursued higher studies till June 1985 and he joined
Central Engineering Service (Roads) in the Ministry
of Road Transport & Highways (MoRTH). During his
probation as Assistant Executive Engineer, he secured
degree of LL.B from University of Delhi in 1989.
He has served in all corners of the country during his field
posting for over 17 years in various capacities spanning
from 1989 to 2011 (except 2000-2005) stationed at
Jammu; Chandigarh; Patna; Shillong; Bangalore;
Guwahati, etc. His remarkable contribution as Engineer
Liaison Officer, Shillong in project preparation for
upgradation of NH-51 near Tura (Meghalaya) gave
him identity when then Hon’ble Prime Minister
Shri I.K. Gujaral announced the approval of this
project under special package to North-Eastern States in
1997. He got recognition as Regional Officer, Bangalore
for his outstanding contribution in construction of
State of Art (SOA) 40 m single span cable stayed ROB
on NH-4 in Bangalore, inaugurated by then Hon’ble
Prime Minister Shri A.B. Vajpayee and the ROB was
declared as the best concrete structure in 2003.
During his posting at headquarters in New Delhi
from 2000 to 2005, in the capacity of Superintending
Engineer (Project), he succeeded in procuring MOEF
clearance for 4-lanning of Belgoria Expressways costing
Rs. 129 Crore in Bengal in a record time of three weeks
INDIAN HIGHWAYS, October 2014
in the year 2000, the project was originally sanctioned
in 1972 for Rs. 2.5 Crore. As Superintending Engineer
(Standards & Research) for over 5 years from
2001 – 2005, he drafted various institutional policy
guidelines of vital importance including mandatory
use of fly ash in road construction within 100 km
from Thermal Power Plants; use of cold applied road
markings paint developed by MoRTH under Research
Scheme R-40; Design Specifications of Weigh in
Motion & Automatic Traffic Counter Cum Classifier
and comprehensive revision of MoRTH Standard
Data Book. He received special commendation for
organizing 1st meeting of SAARC Technical Committee
on Transport held in January, 2005 at New Delhi as
Focal Point Officer (FPO), and attended Dhaka SAARC
Summit of Head of States in 2005 as Chairman of
SAARC Technical Committee on Transportation.
In recognition of his outstanding contribution to the
development of highway sector in India, IRC honoured
him with Pt Jawaharlal Nehru Medal in the year 2005.
Shri Nahar joined National Highways Authority of India
(NHAI) as Chief General Manager (CGM) in 2008 and
worked for three years till 2011. He set the trend in
variety of assignments which includes Procurement
of BOT contracts, SPV of Port Connectivity as
MD, resolution of chronic land acquisition/forest
issues of NHAI projects in Bihar, Jharkhand and
NE States, preparation of blue print of proposed
Expressway Authority of India (EAI) as founder
CGM (Expressways), World Bank funded projects as
Chief Coordinator and Arbitration and Legal matters as
CGM (Legal). As a result, he successfully accelerated
the pace of 678 km 28 EPC Projects of East-West
Corridor in NE Region besides SARDP-NE projects of
Jorabat-Badapani NH-40 and Shillong Bypass.
As Chief Engineer (South Zone) during 2013, Shri Nahar
succeeded in securing approval of the Government to
the long pending projects of Allapuzha and Kollam
Bypasses on NH-47 in Kerala.
Shri Nahar participated in panel discussions and
presented number of papers with special emphasis on
legal aspects and highway patrol for ensuring traffic
safety; new indigenously developed technologies
in road sector, which were published in national and
international journals of repute.
He is widely travelled and represented India in SAARC
for four years, looked after JICA Cell for four years,
member of business delegation to Bangladesh in 2010
and was a delegate for International Expressway
Conference held at Kuala Lumpur in 2011.
5
SHRINKAGE AND CRACKING BEHAVIOR OF CEMENT STABILIZED
MATERIAL IN FLEXIBLE PAVEMENT – A CRITICAL REVIEW
Prabin Kumar Ashish*, Dr. Vasant G. Havanagi** and Dr. Devesh Tiwari***
ABSTRACT
In the wake of depletion of natural available
resources, MORTH (Ministry of Road Transport
and Highways), IRC (Indian Roads Congress)
have strongly recommended to search and
use alternative and local materials for road
construction. In this direction, IRC:37-2012 has
come out with guidelines for the use of cement
stabilized materials in sub base and base layers
of road pavement. The guidelines recommends
the value of modulus in the range of 400 MPa600 MPa for sub base and half of initial modulus
value for base coarse for design in lieu of actual
modulus values which may vary up to 20000
MPa based on the assumption that cement
stabilized material would crack due to shrinkage
and playing of initial construction traffic. Major
cause of cracking is observed to be cement
content, curing period and compaction method.
The width and spacing of cracks of shrinkage
crack depends upon shrinkage stress generated
in cement matrix and restrained provided by
surrounding. The actual reduction in modulus
due to shrinkage and initial traffic recommended
by IRC:37 needs to be authenticated by detailed
FWD test. Extensive beam fatigue test needs to
be carried out before arriving at appropriate
value of load damage exponent value.
1
INTRODUCTION
Cracks appearing in cement treated layers are due to
variety of reasons viz. due to repeated load of traffic,
shrinkage of stabilized material and combination of
both. Cracks may or may not reflect on the wearing
courses. If the width of reflective crack is less than
3 mm; sufficient load transfer normally exists through
aggregate interlock to keep the pavement structure
functioning with suitable structural number and its
serviceability. However if these reflective cracks
becomes wider than 6 mm; they will result into poor
load transfer through aggregate interlocking and
pumping of subgrade material due to intrusion of
water from pavement surface cracks. They will lead
to increased stress in the pavement layer which will
ultimately lead to faster rate of deterioration and
premature failure of the pavement.
This cement stabilised mixture is associated with an
unavoidable phenomenon like shrinkage which will
take place during the hydration process of the cement
in the mixture. The width of shrinkage crack and their
spacing depends upon the shrinkage stress developed
and the gain in strength in the cement treated mixture.
Due to this phenomenon, there is large degradation in
strength and modulus value of the stabilised mixture
(IRC:37-2012, TRH 14(1985), AUSTROADS 2008,
Yeo and Yang Sheng; (2011)). The degree of reduction
in strength and modulus value will depend upon the
amount of shrinkage. Shrinkage cannot be avoided
completely, but by taking proper controlling measure
during initial period of curing, their adverse effect can
be brought down to a level which will not affect the
structural integrity and performance of the pavement.
When the stress is applied beyond the endurance
limit, fatigue cracking in the CTB material will take
place. Research carried out by TRH, 14(1985) have
shown that micro-cracks occurs at stress level of 35%
and more of ultimate load and 25% or more of failure
strain. Regular sealing of these cracks tends to reduce
their adverse effect but their regular sealing will
increase the road maintenance cost, also it will look
unsightly and affect the riding quality of the surface.
2
PROCESS OF CRACKING IN CEMENT
TREATED MATERIAL
Fig. 1 Represents the process of damage initiation in
cement treated base material (Gdoutas; 2005).
*
M.Tech Student, PGRPE, AcSIR, E-mail: [email protected]
** Senior Principle Scientist, Geotechnical Division
*** Principle Scientist, Pavement Evaluation Division
6
Central Road Research Institute, New Delhi
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
Fig. 1 Damage Initiation of Cement Treated Base Course (Gdoutas; 2005)
In the cement treated material, voids are present. These
are due to hydration process of cement or as a result
of deficiencies like aggregate gradation, compaction
effort; W/C ratio etc. Due to the continuous loading
of traffic, in excess of endurance limit of the material,
these voids will coalesce and will propagate the crack.
Fig. 2 represents the fictitious micro-crack model
given by Gdoutas (2005).
Fig. 2 Micro-Cracking Fictitious Crack Model (Gdoutas; 2004)
Coalescence of micro-cracks typically passes through
the Interfacial Transition Zone (ITZ) of the cement
treated material which is the weakest link in material
and finally producing an array of cracks in the
cement treated material. This array of crack imparts
permanent damage to the cement matrix phase and
an increase in fracture area will take place, resulting
into a reduced continuous area for the distribution
of stresses and subsequently reduction in effective
modulus of the material and increase the damage to
the material. This explains the limitations of use of
linear elastic behaviour of the cement treated material
and recommends use of non-linear elastic behaviour
to such material when certain value of stress or strain
is applied (Yeo, Yang Sheng; 2011).
INDIAN HIGHWAYS, October 2014
3MECHANISM of development of
shrinkage cracks in CEMENT
TREATED MATERIAL
Drying shrinkage is the major factor that affects the
pavement performance. Due to volumetric contraction,
a restraining force will generate in the cement matrix
in the form of suction force of pore water. When this
generated suction force exceeds the tensile strength of
matrix, formation of cracks will take place.
The matrix suction force, Ψ, of a purely spherical
meniscus in equilibrium state can be defined as
below;
2t Cosθ
Ψ= n
r
t n
= Surface tension of water;
7
TECHNICAL PAPERS
r
= Radius of meniscus;
θ
= Angle of contact between water and
pore wall.
From the equation, it can be seen that suction force is
inversely proportional to size of meniscus and hence
smaller the pore size, degree of shrinkage will be
more. It explains for the reason behind higher degree
of shrinkage in case of base material containing finer
particle. As the suction force increases in the cement
treated material, tendency of the matrix to crack will
increase, but the final development of cracks will
depend on its tensile strength. This has been explained
in Fig. 3 (TRH 14(1985)).
Fig. 4 Equivalent Damage Model Based Upon Strain
Equivalence Principle (Lee et. al.; 1997)
E = E0 (1 – D)
Where,
E
E 0
D
= Effective modulus
= Initial modulus,
= Damage factor
So, the stress-strain behavior of a damaged material
may be represented as follow,
ε=
Fig. 3 Development of Shrinkage Cracks in Cement Stabilized
Material (TRH (14); 1985)
4Effect of Cracking on Modulus
of Cement Treated Material
Cement treated material is considered as quasi brittle
material which means that material will undergoes
damage in form of nucleation of voids formed from
coalescence of micro-cracks existing within the cement
matrix. This process of damage analysis is based upon
principles of classical mechanics. The process of
damage can also be described by energy principle and
strain equivalence principle as the fracture process
involves the creation of new surface in the material.
Damage function is derived on the basis that virgin
material and its continuum model which must contain
equal strain energy when subjected to same global
displacement. This damage function is represented
on the basis of degradation in elastic modulus which
ultimately results in lowering the capacity to store
strain energy (Lee et. al.; 1997),
8
σ
E0 (1 − D)
When, D = 0, linear elastic behavior is observed.
From this principle, it can be concluded that the
onset of damage will termed as linear elastic limit
or endurance limit of the material and afterwards,
nonlinear behavior of cement treated material will be
observed.
TRH 13 (1986) studied the performance of cement
treated layer during their design life by full scale
field trials with vehicle simulator. Variation of
elastic modulus with number of load repetitions was
evaluated as shown in Fig, 5. The behaviour of cement
treated layer was divided into three distinct phase i.e.
Pre-Cracked phase, Post- Cracked phase and PostCemented phase.
Fig. 5 Effective Modulus Vs Cumulative Traffic Loading during
Different Phases (TRH (13); 1986)
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
5METHOD
CRACKS
OF
CONTROLLING
OF
construction traffic. The values recommended
for design in the IRC guidelines needs to be
authenticated by detailed field investigations by
carrying out FWD tests on the experimental test
tracks.
Various methods which can be adopted to minimize
the shrinkage cracks in cement material are
1)
Controlling of optimum amount of
cement
2)
Use of Admixture in mix
3)
Inducing precracking in newly laid layer
4)
Provision of stress relief layer
3.
The value of Poisson’s ratio and flexural strength
for cement treated material is recommended as
0.25 and 1.5 MPa respectively regardless of the
type of parent material and cement percentage.
These values also vary depending on type of
parent material and cement content. Nunes
(1997) found the value of Poison’s ratio as
0.16-0.18 for Fly ash treated with 2% cement
and 0.14-0.16 for Fly ash treated with 5%
cement. Yang Sheng et. al. (2011) observed
flexural strength of 0.50 to 2.20 MPa for cement
content from 1% to 5% by their experimental
studies on Crushed rock stabilised with cement.
AUSTROADS (2008) observed flexural
strength of 1.01 MPa and 1.13 MPa for Hornfels
stabilised with 3% cement and Siltstone
stabilised with 4% cement respectively.
4.
The load damage exponent used for finding out
fatigue design life is highly dependent upon
the parent material to be stabilised as well as
cement content and is having wide variability
as found in various literature (AUSTROADS
2004; AUSTROADS 2008, Yang Sheng et.al.
2011). Extensive beam fatigue tests under strain
controlled condition needs to be carried out
before arriving at an appropriate value of load
damage exponent.
6COMMENTS FOR RECOMMENDATION
OF IRC:37-2012 ON CEMENTITIOUS
BOUNDED MATERIAL
Various parameters viz. Resilient modulus, Flexural
strength, Poisson’s ratio, Load damage exponent are
very important to arrive at proper thickness of cement
stabilized sub base and base layers of flexible pavement
based on Mechanistic-Empirical (M-E) approach. Use
of appropriate values of these parameters is very much
essential for suitable design. This has been discussed.
1.
2.
For design of flexible pavement, IRC:37-2012
recommends the use of elastic modulus based
upon the correlation with UCS value. Since
the failure for cement treated material is due to
fatigue, this correlation does not seem realistic
for use for thickness design of pavement since
UCS is the compression test rather than tension
test. It is suggested that a suitable value of
resilient modulus needs to be used for design of
cement stabilized material. A correlation needs
to be developed between UCS and Resilient
modulus by extensive laboratory studies.
In IRC:37-2012, the modulus value for stress
analysis/design of sub base layer is recommended
as 400 MPa, for cement treated material having
7 day UCS value of 0.75-1.5 MPa and 600 MPa
for UCS value of 1.5-3 MPa. For design of base
layer, initial modulus is reduced by 50% for
stress analysis. As discussed in section 6, the
reduction of modulus value of cement treated
material depends on shrinkage cracking and
INDIAN HIGHWAYS, October 2014
7CONCLUSION
Naturally available conventional materials are
generally being used in base and sub-base layer of
flexible pavement. This has resulted in enormously
increasing the cost of construction and also has
badly affected the environment. In this direction,
IRC:37 -2012 has come out with guidelines for the use
of cement stabilized materials as alternative materials
in sub base and base layers of road pavement.
9
TECHNICAL PAPERS
Considering the importance of cracking of cement
stabilized layer due to shrinkage and construction traffic
on the design thickness, a detailed literature review
has been carried out regarding shrinkage, the effect
of shrinkage stresses, mechanism and measurement of
shrinkage and also measures to control the shrinkage
cracks. Brief conclusions have been given below:
1.
2.
3.
Drying shrinkage is the major factor that affects
the pavement performance. Due to volumetric
contraction, a restraining force will generate in
the cement matrix in the form of suction force
of pore water. When this generated suction
force exceeds the tensile strength of matrix,
formation of cracks will take place.
There is large degradation in modulus and
strength value due to shrinkage and initial traffic
loading.
At lower strength, crack due to shrinkage will be
narrow, numerous and closely spaced whereas
at higher strength, crack due to shrinkage will
be wider, fewer and further apart.
4.
The process of damage can be described by
continuum damage analysis, energy principle
and strain equivalence principle.
5.
Major factor influencing the shrinkage cracking
are cement content, curing regime for curing
and compaction method adopted for preparation
of cement treated material.
6.
7.
8.
10
The width and spacing of shrinkage cracks
not only depends upon the shrinkage stresses
developed within the cement matrix pores but
also on the restrained force provided by the
surrounding layers.
Major method of preventive measures from
cracks are controlling cement content at
optimum level, use of admixture, by carrying
out pre-cracking, provision of stress relief
layer.
The actual reduction of modulus value due
to shrinkage and initial traffic recommended
for design in the IRC guidelines needs to be
authenticated by detailed field investigations by
carrying out FWD tests on the experimental test
tracks.
9.
The value of Poisson’s ratio and flexural strength
for cement treated material vary depending on
type of parent material and cement content.
10.
Extensive beam fatigue tests under strain
controlled condition needs to be carried out
before arriving at an appropriate value of load
damage exponent.
REFERENCES
1.
AUSTROADS (2004), “Pavement Design: A Guide to the
Structural Design of Road Pavements”, Austroads Inc.,
Sydney, Australia.
2.
AUSTROADS (2008), “The Development and Evaluation of
Protocols for the Laboratory Characterisation of Cemented
Materials”, Austroads Inc., Sydney, Australia.
3.
Gdoutas, E.E. (2005), “Fracture Mechanics: an Introduction”,
Springer, 2nd Edition, Netherlands.
4.
IRC:37-2012, “Guidelines for Design of Flexible Pavement”,
Indian Road Congress, New Delhi.
5.
Lee, U. et.al. (1997), “Anisotropic Damage Mechanics Based
on Strain Energy Equivalence and Equivalent Elliptical
Micro Cracks”, International Journal of Solid Structures,
Vol. 34, pp. 4377-4397.
6.
Nunes (1997), “Enabling the Use of Alternative Materials in
Road Construction”, Ph.D. thesis Submitted to University of
Nottingham, UK.
7.
TRH 13 (1986) “Cementitious Stabilizers in Road
Construction South Africa”, Department of Transport,
Pretoria, South Africa.
8.
TRH 14 (1985), “Cementitious Stabilizers in Road
Construction South Africa”, Department of transport,
Pretoria, South Africa.
9.
Yeo, Yang Sheng (2011), “Characterisation of Cementtreated Crushed Rock Base Course for Western Australian
Roads”, Ph.D. Thesis Submitted to Curtin University, School
of Civil and Mechanical Engineering.
INDIAN HIGHWAYS, October 2014
RHEOLOGICAL PROPERTIES OF NANOCLAY MODIFIED BITUMEN
Mohammed Sadeque* and Dr. K.A. Patil**
ABSTRACT
This paper investigates the potential benefits
of nanoclay/Montmorillonite (MMT) for
improving the properties of bitumen. Bitumen
mixtures were prepared with various amount
of nanoclay. The physical properties like
penetration, softening point, ductility and
strength properties like Marshall Stability of
bitumen modified with nanoclay are evaluated
and compared with neat bitumen. The Dynamic
Shear Rheometer (DSR) study also carried
out on neat and modified bitumen. Based on
the experimental results, it was found that the
addition of nanoclay improves the rheological
properties of bitumen. The penetration
decreases, were as the softening point increases
with addition of nanoclay in bitumen. Asphalt
concrete prepared from nanoclay modified
bitumen shows significant improvement in the
Marshall Stability.
1
INTRODUCTION
strength of bitumen is improved due to addition of
nanoclay in bitumen[2]. With the increase in nanoclay
concentration the tensile strength of dry bitumen mix
sample decreases, but increases for wet sample. Also
nanoclay modified bitumen shows improved moisture
susceptibility i.e. decreases the moisture damage
potential[3].
2Materials and Methods
2.1Materials
For present study 60/70 penetration grade bitumen,
obtained from Shell Corporation India is used as
base material. The physical characteristics of the base
bitumen are as shown in Table 1.
Table 1 Properties of Base Bitumen
Properties
Penetration
Value
Softening
Point
Ductility
Values
67 (dmm)
40 (ºC)
>120 (cm)
Stability of
Flow
Bituminous Bituminous
Mix
Mix
16.38 kN
3.05 mm
The nanoclay technology is a recent development. The
raw material for nanoclay is montmorillonite mineral.
The commercially available nanoclay contains over 98
percentage of montmorillonite. The nanoclays (MMT)
have successfully introduced in the polymer as filler
or additive to enhance the performance of polymer.
The organic layered silicate of MMT has a significant
improvement the mechanical and flammability
behavior of polymer. In the present study the effect
of MMT on the rheological properties like penetration
softening point ductility and stability of bitumen are
evaluated and compared with neat bitumen.
For the present study montmorillonite nanoclay is
supplied by Crystal Nanoclay Pvt. Ltd. Pune, India.
Nanoclay used in the work is Crysnano 1010 P,
organically modified montmorillonite clay having
purity level 98.6%, ash content 38% and basal spacing
of 24 Aº.
Direct Shear Rheometer (DSR) result of MMT
modified bitumen indicate that modified bitumen
exhibit higher complex modulus, lower phase angle
than neat bitumen which indicate higher resistance
to rutting at higher temperature[1]. Nanoclay can
be effectively used as modifier to improve the
mechanical properties of bitumen. Also the tensile
The penetration test is carried out by standard bitumen
penetration test apparatus, measured in terms of
1/10th of mm (dmm), under weight of 100 gm for
5 second at 25ºC. The softening point is determined
by ring and ball method. The ductility is determined in
terms of centimeter at 27ºC. The stability and flow of
bituminous mix is determined by Marshall Method.
2.2Experimentation
Nanoclay modified bitumen samples are prepared in
laboratory by heating bitumen at 200ºC and MMT is
mixed in various percentages (1%, 2%, 3%, 4% and
5%) by weight and stirred for one hour.
*
Research Scholar, Govt. College of Engineering Aurangabad & Associate Professor, Jawaharlal Nehru Engineering College,
Aurangabad, E-mail: [email protected]
**
Associate Professor, Govt. College of Engineering, Aurangabad, E-mail: [email protected]
INDIAN HIGHWAYS, October 2014
11
TECHNICAL PAPERS
The complex modulus and phase angle of neat
bitumen and bitumen modified with 1% of MMT
have been determined. Dynamic shear rheometer test
was conducted at 64ºC temperature subjected to an
angular frequency of 10 rad/sec on a sample of size
25 mm diameters with 1mm gap.
Ductility of bitumen reduces with increase in MMT
concentration. The effect of MMT content on the
ductility of bitumen is represented in Fig. 3. Ductility
of bitumen reduces to 60.5 cm at 5% MMT content.
From the study it is revealed that the physical
properties of bitumen significantly improved by MMT
modification.
3Results and Discussions
Penetration test results indicate that the penetration
value decreases with increase in MMT concentration.
This is an indication of increased stiffness of the binder.
The effects of MMT on penetration value are shown
in the Fig. 1. The penetration value of neat bitumen
was 67 dmm which reduces to 48 dmm at 5% MMT
content. The softening point test result shows that
softening point is increasing considerably with MMT
modification. Softening point of bitumen modified
with 5% of MMT was found to be 52ºC. Effect of
MMT on softening point of bitumen is shown in
the Fig. 2.
12
Fig. 3 Effect of MMT on Ductility Point of Bitumen
Penetration value and ductility decreases while
softening point increases with introduction of MMT,
which can attributed to the formation of exfoliated
structures in the MMT modified bitumen. An
exfoliated morphology occur when clay platelets are
delaminated and completely separated[1].
Fig. 1 Effect of MMT on Penetration of Bitumen
The Marshall Stability test result of neat and MMT
modified bitumen mix shows that the stability value of
MMT modified bitumen mix is considerably improved,
also the flow value decrease which is an indication of
improvement in the resistance against rutting. Stability
value of bitumen mix increases from 16.38 kN to
19.89 kN at 5% of MMT content. Effect of MMT on
Marshall Stability, flow and Marshall Quotient are
indicated in Figs. 4, 5 and 6 respectively.
Fig. 2 Effect of MMT on Softening Point of Bitumen
Fig. 4 Effect of MMT on Stability of Bitumen Mix
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
4Conclusions
Based on laboratory investigations and obtained
results in this study, the following conclusions can be
drawn.
1.
2.
Fig. 5 Effect of MMT on Flow of Bitumen Mix
3.
Fig. 6 Effect of MMT on Marshall Quotient
Dynamic shear rheometer test results on neat bitumen
and bitumen modified by 1% of MMT are shown in
Table 2. The 1% MMT is assumed as optimum dose
on the basis of minimum ductility criteria. From DSR
test results it is found that found that the complex
modulus increase (G*) and phase angle (δ) decreases
and hence the G*/sinδ increases. The term (G*/sinδ),
was recommended as the Superpave specification
parameter to give a measure of the rutting resistance
of bituminous mix. The higher the G* value, the stiffer
will be the binder, thus the more resistant to rutting.
The lower the δ value, the more elastic the binder, an
increase in elasticity makes the asphalt binder more
resistant to permanent deformation.
Table 2 Effect of MMT Concentration on Complex
Modulus Phase Angle of Bitumen
Type of
Additive
Base Bitumen
MMT
Additive Complex
content Modulus
(%)
G* (kPa)
Phase G*/sin δ
Angle (kPa)
(δ)
-
`1.43
87.3
1.43
1%
1.74
85.83
1.74
INDIAN HIGHWAYS, October 2014
The use of MMT as a modifier seems to have
positive effects on physical and strength properties
of the binders, including improved penetration,
softening point.
There is significant improvement in the stability
value of bituminous concrete, also the flow value
decrease and thus Marshall Quotient increases
which is an indication of improved resistance
to rutting. The increase in complex modulus
and decrease in phase angle is an indication of
improved resistance to permanent deformation.
However the ductility of the binder reduces
with increase in MMT content. It is therefore
recommended to use the 2% to 3% of MMT to
keep the ductility with in permissible limit.
Acknowledgement
The authors would like to thank National Rural Road
Development Agency (NRRDA), New Delhi, for
supporting this project.
References
1.
TAO Yuan-Yuan, YU Jian-Ying, LI Bin, FENG
Peng-Cheng, “Effect of Different Montorillonite on
Rheological Properties of Bitumen/Clay Nanocomposite”
J. Cent. South Univ. Technol. 15(s1): 172−175, 2008.
2.
Zhanping You, Julian Mills-Beale, Justin M. Foley, Samit
Roy, Gregory M. Degard, Qingli Dai, Shu Wei Goh,
“Nanoclay-Modified Asphalt Materials: Preparation and
Characterization “Construction and Building Materials,
vol. 25. 1072–1078, 2011.
3.
Shu Wei Goh, Michelle Akin, Zhanping You, Xianming
Shi, “Effect of Deicing Solutions on the Tensile Strength
of Micro-or Nano-Modified Asphalt Mixture” Construction
and Building Materials vol. 25. 195–200, 2011.
4.
Gang Liu, Shaopeng Wu, Martin van de Ven, Jianying
Yu, Andre Molenaar, “Influence of Sodium and OrganoMontmorillonites on the Properties of Bitumen” Applied
Clay Science 49 (2010) 69–73.
5.
Gang Liu, Martin Van de Ven, Shaopeng Wub, Jianying Yu,
Andre Molenaar, “Influence of Organo-Montmorillonites
on Fatigue Properties of Bitumen and Mortar” International
Journal of Fatigue 33 (2011) 1574–1582.
13
MIX DESIGN OF BITUMINOUS CONCRETE BY BAILEY METHOD
Swapan Kumar Bagui* and Sutanu Bhadra**
ABSTRACT
This paper presents the properties of asphalt
concrete mix with aggregate gradations designed
using Bailey Method and compared with
the Indian Specification. Bailey Method is a
systematic approach in blending aggregates with
difference gradation (fine aggregate and coarse
aggregate) that provides aggregate interlocking
as the backbone of the structure and a balanced
continuous gradation to complete the mix. The
aggregates structures designed using Bailey
Method were applied in Marshall Mix Design
Method to obtain the Marshall Properties based
on Indian Standard and the gradation parameters
were compared with the requirement from
MORT&H Specification with a real case study.
The paper presents uses of Bailey Method in
Marshall Mix Design with an example conducted
in the laboratory.
PROBLEM IN TRADITIONAL MIX
DESIGN
Generally, in the conventional method, the mix is
accepted or rejected based on those criteria at an early
stage in the design process without any validation
of their expected performance. An example of such
criteria is the percentage of VMA. It was reported
by several researchers and highway agencies that
there exist difficulties in meeting the minimum VMA
requirements (Kandhal, Foo and Mallick, 1998).
the mix design procedure and analyze the compaction
and performance characteristics of the resulting
Asphalt Concrete (AC) mixtures. The objective of
this paper is also to present a systematic approach to
blending aggregates to achieve desired mix propertiesusing Bailey Method.
The scope of this study is also to determine Marshall
Properties of mix and control various Marshall
Properties like VMA, air void, VFB by adjusting
grading of the aggregate and develop entire design
calculation using Bailey Method developing Excel
Sheet for practical purpose.
3MIX DESIGN METHOD TO DEVELOP
AGGREGATE INTERLOCK
This new method to combine aggregates to give a
desirable mix design requires the understanding of
two concepts:
●
The difference between coarse and fine
aggregate, and
●
Combining aggregates by volume to
ensure coarse aggregate interlock.
1
Furthermore, the trial and error nature of the actual
conventional process of formulating the gradation
curve, and the use of weight instead of volume when
blending aggregates, offer alternatives to evaluate
more rational approaches to design an aggregate
structure based on principles of aggregate packing
concepts (Vavrik et. al. 2002).
2OBJECTIVE AND SCOPE
The objective of this present study is to incorporate an
analytical gradation design and evaluate method into
3.1Coarse Versus Fine
For the purposes of the study of Bailey Method, it
is necessary to change those traditional definitions
to properly analyze a mix gradation and determine
the packing and aggregate interlock provided by the
combination of all aggregates in the mix. In this study
analysis of aggregate blending for bituminous mix,
the following definitions of coarse and fine aggregate
are used:
●
Coarse aggregate: large aggregate
particles, when placed in a unit volume,
create voids; and
●
Fine aggregate: aggregate particles
that fill the voids created by the coarse
aggregate.
*
Chief General Manager, ICT Pvt. Ltd., New Delhi, E-mail: [email protected]
**
Director, Solo Consultancy Services Pvt. Ltd., Kolkata
14
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
The sieve that separates the coarse and fine aggregates
is called the Primary Control Sieve (PCS) and is
dependent on the NMPS of the aggregate blend. The
PCS is mathematically defined as 0.22 of the NMPS
based on two and three-dimensional analysis of the
packing of different-shaped particles. Furthermore, the
aggregate blend below the PCS is divided into medium
and fine portions and each portion is evaluated.
3.2
Particle and Aggregate Packing
For coarse aggregates there are three governing
weights that must be determined. The weights are
the Loose Unit Weight (LUW), Rodded Unit Weight
(RUW), and the Chosen Unit Weight (CUW).
The range for a dense graded coarse mix is 95% to
105% of the loose unit weight of coarse aggregate
for a mix that will obtain some degree of coarse
aggregate interlock and 110% for Stone Mix Asphalt.
The percent chosen unit weight for a fine graded mix
should be less than 90% of the loose unit weight of
coarse aggregate. The percent chosen unit weight
range between 90% and 95% should be avoided due
to the high probability of varying in and out of coarse
aggregate interlock (Vavrik, et. al., 2002).
Table 1 displays the general effect on the VMA based
on changes in the four parameters (Vavrik, et. al.,
2002).
Table 1 Effects of Increasing Bailey Parameters on VMA
Bailey Parameter
VMA Amount for Different Mixes
Coarse Blend
Fine Blend
SMA
Percent Chosen Unit Weight/PCS(Increase)
increases
decreases
increases
CA(Increasing)
increases
increases
increases
FAc(Increase)
decreases
decreases
decreases
FAf(Increase)
decreases
decreases
decreases
4BAILEY METHOD BITUMINOUS MIX
DESIGN
4.1History
The concepts and methods presented herein are based
on the years of experience in designing mix of Robert
Bailey (retired), Materials Engineer of the Illinois
Department of Transportation.
4.2
Applicability
Bailey method is suitable for dense-graded mix but
can be applied to stone matrix bituminous and finegraded mixes with some modification (Vavrik 2002).
The Bailey Method rests on two basic principles:
aggregate packing, coarse and fine aggregate definition.
Bailey Method proposes a definition of coarse and fine
aggregate which already described in Section 3.1.
Equation 1 shows the Bailey Method definition of
primary, secondary, and tertiary control sieves. The
half-sieve is defined in the Bailey Method as shown
in Equation 2. Use of the standardized set of sieves is
INDIAN HIGHWAYS, October 2014
shown in Table 2. Equations 1 and 2 result the control
sieves which are shown in Tables 3 and 4. Further to
the control sieves, the Method defines three aggregate
ratios (Equation 3) to characterize the coarse, the
coarse portion of the fine, and the fine portion of the
fine aggregate in the mix:
Table 2 Standard Sieve Sizes for Bituminous Works
Sieve
1
2
3
4
5
6
7
8
9
10
11
12
Size (mm)
37.5
25.0
19.0
12.5
9.5
4.75
2.36
1.18
0.600
0.300
0.150
0.075
15
TECHNICAL PAPERS
PCS = 0.22 NMPS
... (1a)
SCS = 0.22PCS
... (1b)
TCS = 0.22SCS
... (1c)
IRC:111-2009 defined MNPS as ‘the largest sieve size
on which certain percent retained aggregate’.
Half–Sieve = 0.5 × NMPS
... (2)
Table 3 Bailey Coarse Mix Control Sieves
Designated
Sieves (mm)
Half Sieve
PCS
SCS
TCS
... (3b)
FAf = (% passing TCS/% passing SCS)
... (3c)
Where CARatio is the coarse aggregate ratio and FAc
and FAf are the fine aggregate coarse and the fine
aggregate fine ratios, respectively.
19
9.5
2.36
0.6
NMPS ( mm )
25.0 19.0
12.5
4.75
1.18
0.3
9.5
4.75
1.18
0.3
12.5
9.5
4.75
4.75
2.36
0.6
0.15
4.75
2.36
0.6
0.15
2.36
1.18
0.3
0.075
Table 4 Bailey Fine Graded Mix Control Sieves
CARatio = (% passing half sieve - % passing PCS)/
(100% - % passing half sieve)
... (3a)
FAc = (% passing SCS/% passing PCS)
37.5
Designated
Sieves
37.5
25.0
NMPS (mm)
19.0
12.5
9.5
4.75
Original PCS
New Half Sieve
New PCS
New SCS
New TCS
9.5
4.75
2.36
0.60
0.15
4.75
2.36
1.18
0.30
0.075
4.75
2.36
1.18
0.30
0.075
2.36
1.18
0.60
0.15
*
1.18
0.60
0.30
0.075
*
2.36
1.18
0.60
0.15
*
Table 5 gives recommended ranges for the aggregate
ratios (defined in Equation 3) for initial mix designs.
Table 5 Recommended Aggregate Ratio Range for Coarse Mix
Control Sieve
CARatio
FAc
FAf
NMPS
37.5 mm
0.80-0.95
0.35-0.50
0.35-0.50
NMPS
25.0 mm
0.70-0.85
0.35-0.50
0.35-0.50
NMPS
19.0 mm
0.60-0.75
0.35-0.50
0.35-0.50
CA ratio shall be changed to 0.6-1.0 for all nominal
maximum particle size.
The change in Bailey parameters that result change in
1% VMA is shown in Table 6.
NMPS
12.5 mm
0.50-0.65
0.35-0.50
0.35-0.50
NMPS
9.5 mm
0.40-0.55
0.35-0.50
0.35-0.50
NMPS
4.75 mm
0.30-0.45
0.35-0.50
0.35-0.50
Void has been determined at lose weight, 10 blows
and 25 blows to determine graphical representation. A
typical representation is shown in Fig.1.
Table 6 Change in Bailey Parameters to
Produce Change in 1% VMA
Note :
5
Parameter
Unit Weight
CA
FAc
FAf
Change in Values
4% in PCS/6%*
0.20/0.35*
0.05
0.05
* Fine Blending
DEVELOPING COMBING GRADING IN
LABORATORY
After gathering the typical information for the
individual aggregates (gradation, specific gravity
etc.) and performing the unit weight tests, a combined
blend can be developed and evaluated with respect to
the following main principles of the Bailey Method,
prior to actually blending the mix in the laboratory.
16
Fig. 3 Chosen Unit Weight as Percentage of Loose Unit Weight
Step 1: Determine the Mix Type and NMPS.
NMPS and mix type (coarse/fine) is typically a
function of specification requirement. Individual
grading is shown in Table 7. From Table 7, it is found
that 26.5 mm sieve is nominal maximum particle size,
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
9.5 mm sieve is the PCS. Major portion of 40 mm
and 20 mm aggregates are retained on 9.5 mm sieve.
Therefore, 40 mm and 20 mm are coarse aggregate.10
mm and dust are fine aggregate. Lime has been treated
as filler material.
Table 7 Adopted Individual Grading of Aggregate
IS Sieve
40 mm
20 mm
10 mm
Stone Dust Lime
37.5
100
100
100
100
100
26.5
46.9
100
100
100
100
19
3.17
65.65
100
100
100
13.2
1.03
20.19
100
100
100
4.75
0
0.08
1.5
96.5
100
2.36
0
0
0.5
78.5
100
1.18
46
100
300 µ
0
0
0
21
100
75 µ
0
0
0
10.5
92
Step 2: Choose the Volume of Coarse Aggregate.
The coarse aggregate volume expressed as a percentage
of loose weight condition and should be within the
suggested ranges for mix type (Coarse/Fine). Based
on experience, 90% loose unit weight is taken as
preliminary chosen unit weight.
Step 3: Blend of Individual Coarse Aggregate by
Volume.
A stock pile is considered to be coarse if majority of its
gradation is retained on the PCS of the combined blend.
20 mm and 40 mm aggregates are coarse aggregate.
Step 4: Blend of Individual Fine Aggregate by
Volume.
A stock pile is considered to be fine if majority of its
gradation is passed through the PCS of the combined
blend. Two stock piles are used.
Step 5: Lime is used as a separate filler material. It is
considered 1% by weight.
After completing Steps 1 to 5, the designer shall be
established a percentage by weight or mass of each
individual aggregate as 100% total aggregate and
therefore combined blend.
Few experiments were undertaken to validate the
Bailey Method concepts for conducting mix design of
DBM 1 in the laboratory. This experiment involved
INDIAN HIGHWAYS, October 2014
aggregate testing and bituminous mix testing.
The following results are a subset of the complete
experiment that demonstrates the power of the Bailey
Method concepts.
5.1
Dense Bituminous Macadam (DBM)
Bailey Method is used for conversion of volume
proportion of aggregates into weight proportion of
aggregates satisfying specification grading and Bailey
Parameters. An excel sheet has been developed and
shown in Annexure 1.
Mix design of a project has been considered as a
case study. Aggregate of local Quarry located near
the project area is used in the Mix design. Individual
grading and combined grading are shown in Tables 7
and 8. Proportion of aggregates taken from various
bins namely HB-4, HB-3, HB-2, HB-1 and Filler
are 10%, 25%, 16%, 48% and 1% respectively.
Specific gravity and other properties were determined
in the laboratory. Other properties are shown in
Annexure 1.
VG 30 bitumen was used for preparation of DBM1.
Properties of bitumen is found satisfactory within
permissible limit of MORTH Specification.
Marshall moulds are prepared with varying bitumen
content and optimum bitumen content is found 4.5%.
Air void, VMA, VFB, bulk density, flow and stability
were found 4.32%, 14.1%, 69.32%, 2.445 gm/cc,
3.3 mm and 1410 Kg respectively. Bailey Method is
also used to determine variation of VMA calculation.
Detail calculation of variation of VMA and actual
values are reported in Table 8.
Table 8 Variation of VMA
Properties
Sieve
JBF
Trial 1
37.5
100.0
100
NMPS
26.5
94.7
94.69
19
81.7
82.073
HALF
13.2
70.2
70.9486
PCS
4.75
47.6
44.7442
2.36
38.8
36.425
SCS
1.18
23.1
21.7
17
TECHNICAL PAPERS
Properties
VMA and VFB curves for varying bitumen content
and grading pattern are observed. Air void and VMA
values are higher side for coarser grading and lower
side for finer grading whereas VFB is reverse in nature
for known bitumen content. These shall be helpful for
adjustment of Marshal Properties. Practical data are
considered for preparing the graphs. However it will
give a general idea how to change Marshal Properties
changing gradation.
Sieve
JBF
Trial 1
TCS
300 µ
11.1
10.45
75 µ
6.0
5.645
Bitumen Content (%)
4.5
4.41
Bulk Density (g/cc)
2.445
2.429
Max. Sp. Gravity (Gmm)
2.55
2.548
Air Voids (Va) %
4
4.6
VMA %
14.1
14.2
VFB %
71.6
68.5
STABILITY (kN)
12.63
12.78
FLOW (mm)
3.3
3.1
The following specific conclusions are drawn:
CA
0.76
0.90
●
Fac
0.49
0.48
Faf
0.48
0.48
Change in PCS
-2.84
Change in CA
0.15
Change in Fac
0.00
Mix design concepts outlined here provide the
basic guideline for a comprehensive asphalt
mix design method: the Bailey Method. Design
Steps shown in Sections 3.1 and 5 and design
calculation reported in Annexure 1 shall be
used for conducting Mix Design of asphalt.
Change in Faf
0.00
●
Change in VMA due to change
in Unit Weight
-0.47263
Change in VMA due to change
in CA
0.416737
Weight proportion along with grading
optimization as shown in Fig. 1 is an important
design concept of practical uses.
●
Change in VMA due to change
in Fac
0.001974
Approximate VMA calculation shown in
Table 8 shall be useful for practical field use
when there is a need in change of VMA.
Change in VMA due to change
in Faf
-0.02995
●
Total Change in VMA (%)
-0.08387
It is essential for requirement of training for
Bailey Method for the use in the practical field.
●
Calculated VMA (%)
14.17
Actual VMA Obtained
14.17
Bailey Method may be used when mix design is
unsatisfactory marginally. Marshall Properties
may be changed using concept of Bailey Method
of Mix Design of Asphalt.
From Table 8, it is found that calculated VMA
values are found more or less closed to actual values.
Therefore, VMA properties can be altered and it is also
possible to achieve desired VMA adjusting grading.
An excel sheet has been prepared for determining
Bailey Parameters and is shown in Annexure 1.This
sheet shall be useful for practicing engineer to control
mix and produce durable mix.
Marshall Moulds are also prepared considering coarse,
medium and fine grading. General tendency of air void,
18
6CONCLUSION
REFERENCES
1.
Kandhal, P.S., K.Y. Foo, and R.B. Mallick. Critical Review
of Voids in Mineral Aggregate Requirements in Super pave.
In Transportation Research Record 1609, TRB, National
Research Council, Washington, D.C., 1998, pp. 21–27.
2.
Vavrik, W.R., G. Huber, W. J. Pine, S. H. Carpenter, and
R. Bailey. Transportation Research Circular E-C044: Bailey
Method for Gradation Selection in Hot-Mix Bituminous
Mixture Design. Transportation Research Board of the
National Academies, Washington, D.C., 2002.
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
Annexure 1: Determination Bailey Parameters
Specific Gravity
2.761
2.756
2.742
2.726
2.46
Agg. Type
HB4
HB3
HB2
HB1
Filler
Proportion (Vol)
0.053
0.150
0.200
0.567
0.030
Proportion (Weight)
0.102
0.284
0.137
0.469
0.008
Sieve Size
Theoritical
Combined
Grading
Lower
Limit
Mid
Limit
Upper
Limit
37.5
100.0
100.0
100.0
100.0
100.0
100.00
100.00 100.00 100.00
26.5
46.9
100.0
100.0
100.0
100.0
94.59
90.00
95.00
100.00
19
3.2
65.7
100.0
100.0
100.0
80.36
71.00
83.00
95.00
13.2
1.0
20.2
100.0
100.0
100.0
67.22
56.00
68.00
80.00
4.75
0.0
0.1
1.5
96.5
100.0
46.28
38.00
46.00
54.00
2.36
0.0
0.0
0.5
78.5
100.0
37.67
28.00
35.00
42.00
46.0
100.0
22.36
1.18
300µ
75µ
0.0
0.0
0.0
21.0
100.0
10.64
7.00
14.00
21.00
5.65
2.00
5.00
8.00
0.0
0.0
0.0
10.5
92.0
90 % LUW (t/Cum)
1.292
1.274
RUW (t/Cum)
1.610
1.583
1.560
1.886
0.602
90
90
Loose Void
53.2%
53.8%
Rodded Void
41.7%
42.6%
Coarse void
53.6%
Coarse Vol =
46.4%
Fine Vol =
53.6%
Weight
(Kg)
Weight
Proportion
CA1
12.1%
0.16
1564.47
0.102
CA2
34.3%
0.44
4363.01
0.284
CA3
13.5%
0.21
2099.63
0.137
CUW
43.1%
30.8%
CA4 =
38.2%
0.72
7196.37
0.469
Filler
2.0%
0.01
121.54
0.008
90 % LUW Coarse Combined
1.28
Total Weight
15345.02
Com Loose Void
75.5%
53.6%
Trial Vol Proportion
0.053
0.150
0.200
0.567
Achieve Weight Proportion
0.102
0.284
0.137
0.469
Annexure 1Determination Bailey Parameters (Cont.)
Adopt weight proportion = (10:25:16:48:1) and revised value is mentioned below
Bailey Parameter
CA
Fac
FAf
Actual Value
0.76
0.49
0.48
0.6-1.0
3.5-0.50
3.5-0.50
Limit
INDIAN HIGHWAYS, October 2014
19
SUBGRADE CHARACTERISTICS OF SAND–FLY ASH–LIME COMPOSITE
R.K. Sharma*
ABSTRACT
Fly ash is an industrial waste produced by
the burning of coal in thermal power plants.
Worldwide, most of the fly ash produced is
disposed of in landfills. The properties of fly
ash are somewhat unique as an engineering
material. Unlike typical soils used for
embankment construction, fly ash has large
uniformity coefficient consisting of silt-sized
particles mostly. The gradation of fly ash can
be modified by addition of sand and unit weight
of the composite also increases.
This study has been undertaken to explore
possibility of using fly ash in combination with
sand and lime. The engineering properties of
composite material (fly ash- sand-lime) have
been studied to bring out the possibility of using
fly ash in the construction of embankments.
Addition of sand to fly ash results in an increase
in Maximum Dry Density (MDD) with a
decrease in Optimum Moisture Content (OMC).
Further, there is also a significant increase in
the California Bearing Ratio (CBR) value with
the addition of sand. The composites consisting
of 60% fly ash + 40% sand and 40% fly ash +
60% sand were further tested by adding lime.
Addition of lime led to a decrease in MDD but
there was an increase in the CBR value. The
composite consisting of 40% fly ash + 60%
sand with 2% lime resulted in a soaked CBR
value of 9.0 at Maximum Dry Density (MDD)
of 1.55 g/cm3. This composite may be used for
the construction of subgrade for rural roads.
1
INTRODUCTION
Fly ash is one of the industrial residues generated in
the combustion of coal. In the past, fly ash produced
from coal combustion was simply dispersed into the
atmosphere. This created environmental and health
hazards. Worldwide, more than 65% of fly ash produced
is disposed of in landfills. In India alone, fly ash
landfills cover an area of 40,000 acres (160 km2). Soil
*
20
stabilization involves addition of fly ash to improve
engineering performance of soil. Other environmental
benefits of recycling fly ash include reducing demand
for virgin materials that would need quarrying and
substituting materials which may be energy intensive
to produce. This study has been undertaken to explore
the possibility of using fly ash in combination with
sand and lime. The engineering properties of the
composite material (fly ash-sand-lime) have been
studied. The results have been discussed to bring out
the possibility of use of fly ash in the construction
of rural road sub-grades. Beeghly (2003) showed in
his study that a combination of lime and fly ash is
beneficial for high silt content soils. Jirathanathworn
and Chantawarangul (2003) reported that by using fly
ash mixed with small amount of lime, it is possible
to improve some of the engineering properties of
clayey soil including hydraulic conductivity as well as
strength. Chauhan et al (2008) observed that optimum
moisture content increases and maximum dry density
decreases with increased percentage of fly ash mixed
with silty sand. At present, about 10% ash is utilized in
ash dyke construction and land-filling and only about
3% of ash is utilized in other construction industries.
So far the combination of fly ash, river sand and lime
has not been studied in detail.
2
NEED
FOR
UTILIZATION
SUBGRADE CHARACTERISTICS
AND
Fly ash causes environmental pollution, creating
health hazards and requires large areas of precious
land for disposal. Fly ash possesses several desirable
characteristics such as light weight, ease of compaction,
faster rate of consolidation, better drainage, etc.
Compared to soil, spreading and compaction of
fly ash can be started much earlier after rainfall. In
construction of embankments over weak subsoil,
fly ash could be preferred material. Subsequently,
it is now mandatory to use fly ash at all road works
which are located within a 100 km distance from a
thermal power station (IRC:SP:20-2002). As per IRC
guidelines (IRC:37-2001), the sub-grade material may
be classified on the basis of CBR values as very poor
for CBR value of 2, poor for CBR value of 3 - 4, fair
Professor, National Institute of Technology Hamirpur, H.P., E-mail: [email protected]
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
for CBR value of 5 – 6, good for CBR value of 7 - 9
and very good for CBR value of 10 - 15.
IRC:SP:89-2010 containing guidelines for soil,
material stabilization using cement, lime and fly ash
is useful for selecting proper stabilized materials
based on local soil. The objective of this experimental
research work was to develop a fly ash-sand-lime
composite having CBR value greater than 10 (very
good) preferably or at least in the range of 7 - 9
(good).
their combinations are shown in Fig. 1 (IS:2720
(Part IV) 1975). The basic properties of sand and fly
ash are given in Table 1. The chemical composition of
hydrated lime is given in Table 2.
3SCOPE AND OBJECTIVES
In this study, engineering properties of different
proportions of fly ash, sand and lime have been studied
to bring out the possibility of using the composite for
construction of sub-grades for rural roads. Fly ash is
obtained from Ropar thermal power plant and sand
obtained from river Beas. The objectives of the study
are:
1.
2.
3.
4.
Fig. 1 Particle Size Distribution Curves of Beas Sand,
Fly Ash and Sand + Fly Ash Composite
Table 1 Basic Properties of Beas Sand and Fly Ash
Particulars of test
Sand
Fly ash
Specific Gravity
IS:2720 (Part 3) 1980
2.65
1.85
Geotechnical properties of fly ash and sand were
determined individually and in combinations
varying at intervals of 20%.
Coefficient of uniformity Cu
2.04
3.10
Coefficient of curvature Cc
1.36
1.75
SP
-
Fly ash and sand were mixed in varying
percentages and maximum dry density and
optimum moisture content of the mix were
determined.
Hydrated lime in percentages of 2%, 4%, 6%
and 8% was mixed with two combinations of fly
ash and sand (60:40 and 40:60) and compaction
and California bearing ratio (CBR) tests were
conducted.
The CBR value of the most appropriate
combination of fly ash and sand with varying
percentage of lime has been studied at the
optimum moisture content and maximum dry
density.
Liquid Limit (%)
IS:2720 (Part V) 1975
-
45.5
Plastic Limit (%)
-
NP
Maximum dry density (g/cc)
IS:2720 (Part VII) 1980
1.83
1.19
Optimum moisture content (%)
IS:2720 (Part II) 1973
10.5
25.8
Soaked CBR (%)
IS:2720 (Part 16) 1979
13.8
2.9
4ENGINEERING
PROPERTIES
MATERIALS USED
OF
The materials used in the study were fly ash, Beas
sand and hydrated lime in the powder form. According
to Indian standard soil classification system, the
sand was classified as poorly graded sand (SP). The
particle size distribution curves for fly ash, sand and
INDIAN HIGHWAYS, October 2014
IS soil classification
Table 2 Chemical Properties of Lime
Particulars of test
Calcium and Magnesium Oxides
(non-volatile, %)
Carbon dioxide (%)
Un-hydrated Oxides (%)
95.6
4.9
7.5
4.1Method of Testing
Laboratory tests were conducted as per relevant Indian
Standards in two phases:
1.
Mixing of sand with fly ash in varying
percentages of 20%, 40%, 60% and 80%.
21
TECHNICAL PAPERS
2.
Mixing of sand with 40% and 60% fly ash for
varying lime content in range of 2% - 8% with
increment of 2%.
The mixing was carried out manually and utmost
care was taken to attain a uniform mix. Firstly,
the determination of the properties like moisturedensity relation (IS light compaction) and CBR
for the sand blended with varying percentage of fly
ash was undertaken. Subsequently, effect of lime
content (varying from 2% to 8% with increment of
2%) for sand blended with 40% and 60% of fly ash
on properties like moisture-density relation and CBR
were evaluated.
The variation of Maximum Dry Density (MDD) and
Optimum Moisture Content (OMC) with increase in
percentage of sand is shown in Fig. 3. The variation
in maximum dry density can be expressed in terms of
the linear relationship given by equation:
5RESULTS AND DISCUSSION
5.1Compaction Characteristics of Sand Fly Ash
Composite
IS light compaction tests were carried out on different
proportions of Beas sand and fly ash in accordance
with the procedure laid in IS:2720 (Part VII) 1980/87
in order to study the moisture - density relationship.
Fig. 2 shows that the variation of dry density with
water content for Beas sand, fly ash and different
combinations of Beas sand and fly ash. It is observed
that the Maximum Dry Density (MDD) increases
with increase in sand content whereas the optimum
moisture content decreases. This may be due to the
higher specific gravity and coarser nature of sand than
fly ash which leads to an increase in MDD and the
lower specific surface of sand leads to decrease in
OMC.
Fig. 3 Variation of MDD and OMC of Fly Ash-Sand Composite
ρ = 0.006 p + 1.165 ... (1)
where,
ρ
= maximum dry density in g/cm3 and
p
= sand content in percent.
The variation of Optimum Moisture Content (OMC)
can be expressed by the equation:
w = - 0.152 p + 27.23
... (2)
where,
w
= optimum moisture content in percent
and
p
= sand content in percent.
5.2Compaction Characteristics of Sand Fly Ash
Lime Composite
Fig. 2 Variation of Dry Density of Beas Sand with
Fly Ash Content
22
Based upon the compaction characteristics, the
combinations of 60% fly ash + 40% sand and 40% fly
ash + 60% sand were tested with addition of lime to the
composite. IS light compaction tests were conducted
on the composite samples of 60% fly ash + 40% sand
and lime content varying from 2% to 8%. Fig. 4 shows
that the variation of dry density with water content for
fly ash- sand (60:40) and lime content. It is observed
that the Maximum Dry Density (MDD) decreases
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
with increase in lime content whereas the optimum
moisture content increases. This may be attributed to
lower specific gravity and larger specific surface of
lime compared with sand and fly ash.
is more suited for the construction of sub-grade. The
variation of Maximum Dry Density (MDD) of fly ashsand (60:40) and (40:60) composites with increase in
lime content can be expressed by the equations:
ρ = - 0.021 C + 1.414
...(3) and
ρ = - 0.021 C + 1.586
... (4)
where,
ρ
= maximum dry density in g/cm3 and
C
= lime content in percent.
Fig. 4 Compaction Characteristics of Fly Ash + Sand (60:40)
and Lime Composite
Fig. 5 shows that the variation of dry density with
water content for fly ash - sand (40:60) and lime
content. The Maximum Dry Density (MDD) decreases
with increase in lime content whereas the optimum
moisture content increases.
Fig. 6 Variation of Maximum Dry Density of
Fly Ash-Sand with Lime Content
Fig. 7 shows a comparison of variation of Optimum
Moisture Content (OMC) of fly ash:sand (40:60
and 60:40) with lime content. It is observed that the
OMC is lower for fly ash:sand::40:60 combination as
compared to that for fly ash:sand::60:40 combination.
Hence, fly ash:sand::40:60 combination is more stable
for the construction of sub-grade. The variation of
Optimum Moisture Content (OMC) of fly ash-sand
(60:40) and (40:60) composites with increase in lime
content can be expressed by the equations:
Fig. 5 Compaction Characteristics of Fly Ash + Sand (40:60)
and Lime Composite
Fig. 6 shows a comparison of variation of MDD of
fly ash:sand (40:60 and 60:40) with lime content. It is
observed that the MDD is higher for fly ash:sand::40:60
combination as compared to that for fly ash:sand::60:40
combination. Hence, fly ash:sand::40:60 combination
INDIAN HIGHWAYS, October 2014
w
= 0.625 C + 21.1
... (5) and
w
= 0.475 C + 19.9
... (6)
where,
w
= optimum moisture content in percent
and
C
= lime content in percent.
23
TECHNICAL PAPERS
CBRs= 0.097 p + 2.657
... (8)
where,
Fig. 7 Variation of Optimum Moisture Content of
Fly Ash-Sand with Lime
5.3Strength Characteristics of Sand Fly Ash
Composite
California Bearing Ratio (CBR) values for different
composites were obtained by compacting the
composites to a MDD and OMC corresponding to
IS light compaction and tests were carried out under
un-soaked and soaked conditions to study their load
bearing capacity.
Fig. 8 shows the variation of CBR of fly ash-sand
composite with increase in sand content. It is observed
that there is almost a linear increase in the CBR value
with an increase in the percentage of sand in the
composite following the equations:
CBRu= un-soaked CBR,
CBRs= soaked CBR and
p
= sand content in percent
The above increase in CBR value can be explained
on the basis that sand is a stronger material than fly
ash. The value of soaked CBR for construction of
sub-grade for road embankments should be preferably
in the range of 5.5% to 7.5%. Hence, from the above
tests it can be concluded that the samples of 60%
fly ash + 40% sand and 40% fly ash + 60% sand are
appropriate for further modification by using lime. On
further increasing the percentage of sand, the amount
of fly ash decreases thus leading to a rise in the cost.
5.4Strength Characteristics of Sand Fly Ash
Lime Composite
California bearing ratio (CBR) tests were conducted
under un-soaked and soaked conditions on fly ash-sand
combinations of 60% fly ash + 40% sand and 40% fly
ash and 60% sand with addition of lime varying from
2% to 8% to the composite.
Fig. 9 shows a comparison of the variation of CBR
values with increasing percentage of lime in fly
ash-sand (40 : 60) and (60:40) composites. The CBR
value achieved is higher for fly ash-sand (40:60)
composite as compared to that for fly ash-sand (60:40)
composite. In order to obtain a value of CBR between
8 and 10, addition of 4% to 6% lime content is
required. However, the addition of lime leads to lower
maximum dry density of the fly ash-sand composite.
The variation of unsoaked and soaked CBR values
of fly ash-sand (40:60) and (60:40) composites with
increase in lime content can be expressed by the
equations:
For unsoaked condition:
Fig. 8 Variation of California Bearing Ratio of
Fly Ash-Sand Composite
For unsoaked condition:
CBRu= 0.201 p + 4.242
and for soaked condition:
24
... (7)
CBRu= 0.615 C + 16.14
CBRu= 0.64 C+ 11.8
... (9)
... (10)
and for soaked condition:
CBRs= 0.295 C + 8.36
CBRs= 0.317 C + 6.13
... (11)
... (12)
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
where,
CBRu = un-soaked CBR,
CBRs = soaked CBR and
C
= lime content in percent.
3.
4.
5.
Fig. 9 Comparison of CBR Values for Fly Ash-Sand
(60:40 & 60:40) with Lime
The increase in the CBR value is due to the reaction
between lime and pozzolanic material (fly ash). The
addition of 2% to 4% lime content is adequate to
obtain a value of CBR between 8 and 10. Further increase
in lime content leads to lower maximum dry density of
the composite.
For fly ash:sand (40:60) having lime content more than
6%, the CBR value is in very good category (>10%),
where as for lime content of 2-4%, the CBR value is in
good category (7-9%) as per IRC:37-2001. Further, for
fly ash:sand (60:40) having lime content 4-8%, the CBR
value is in good category (7-9%). Hence, composite mix
containing fly ash:sand (40:60) with lime content in the
range of 2-8%; the CBR value may be considered for the
design of sub-grade of rural road pavements.
6CONCLUSIONS
Fly ash is a waste material produced by the burning of
coal in thermal plants and has low specific gravity and
CBR value. The addition of river sand and lime to fly ash
improves the properties of the composite thus formed,
and allows its application in the construction of roads
leading to a safe disposal of fly ash. Based upon the
above study the following conclusions can be drawn:
1.
Addition of sand to fly ash results in an increase in
maximum dry density with a decrease in optimum
moisture content.
2.
The composites of 40% fly ash + 60% sand and
60% fly ash + 40% sand were further tested with
INDIAN HIGHWAYS, October 2014
6.
the addition of lime. The addition of lime led to a
decrease in maximum dry density and an increase
in optimum moisture content.
Further, there is significant increase in the CBR
value with addition of sand to fly ash. The
composites of 40% fly ash + 60% sand and 60%
fly ash + 40% sand give suitable results of CBR
for use in construction of sub-grade for rural
roads. On further increasing the percentage of
sand in the composite, amount of sand required
increases and composite becomes uneconomical.
The addition of lime led to a decrease in maximum
dry density and increase in optimum moisture
content but there was an increase in the CBR value
and the composite was found to be more stable.
Based upon the test results, it can be concluded
that 2% to 6% of lime may be added when 60%
fly ash + 40% sand composite is used. On further
increasing the percetage of lime, the MDD
decreases significantly. Hence, higher percentage
of lime should not be used. Similarly, 2% to 4% of
lime may be added when 40% fly ash + 60% sand
composite is used so that appropriate values of
CBR are obtained. This composite is best suited
for construction of sub-grades for rural roads.
The above conclusions are based upon the results
of laboratory investigations and need to be further
validated under field conditions.
REFERENCES
1.
2.
3.
4.
5.
6.
Beeghly J. H. (2003) “Recent Experiences with Lime –
Fly Ash Stablization of Pavement Subgrade Soils, Base
and Recycled Asphalt”, International Ash Utilisation
Symposium, Centre for Applied Energy Research, University
of Kentucky, Paper # 46.
Chauhan M.S., Mittal S. and Mohanty B. (2008)
“Performance Evaluation of Silty Sand Subgrade Reinforced
with Fly Ash and Fiber”, Geotextiles and Geomembranes,
Volume 26, Issue 5, pp. 429-435.
IRC:SP:20-2002, “Rural Roads Manual” Indian Road
Congress, New Delhi, India.
IRC:37-2001, “Guide Lines for the Design of Flexible
Pavements”, Indian Roads Congress, New Delhi, India.
IRC:SP:89-2010, “Guidelines for Soil and Granular Material
Stabilization using Cement Lime and Fly Ash”, Indian Road
Congress, New Delhi, India.
Jirathanathworn, Nontananandh T.S. and Chantawarangul
(2003) “Stabilization of Clayey Sand using Fly Ash Mixed
with Small Amount of Lime”, Proc. of the 9th National
Convention on Civil Engineering, Engineering Institute
of Thailand and Thammas at University, Petchaburi, 2:
GTE 93-98.
25
FAILURE OF BRIDGE DUE TO INADEQUATE HYDRAULIC
INVESTIGATIONS
Dr. C.V. Kand*, Yogita Gupta**
ABSTRACT
A high submersible bridge is a bridge which
carries the roadway above the highest flood
level but without vertical clearance above
affluxed HFL to the lowest point of the
superstructure i.e. HFL is at soffit level. A
hydrologic and hydraulic analysis is required
for efficient and economical design of bridges
over waterways. Hydraulic calculations are
necessary to determine hydraulic data such as
discharge, velocity, scour depth, afflux etc. and
special attention is required if bridge is located
at upstream or down stream of a dam. This case
study showing the failure of high submersible
bridge due to improper hydraulic analysis. The
bridge is situated on the upstream of dam on
the same river. The effect of dam was ignored
while calculating velocity, discharge and other
hydraulic parameters. The specified design
discharge and design velocity were on lower
side.
1
Introduction
The failures of hydraulic structures are very expensive,
as in most cases the indirect cost is many times larger
than the direct cost of bridge replacement. Some
hydraulic structures have failed in past mainly due to
(1)
(2)
Length between end of dirt walls
Span Arrangement & Returns
(3)
Deck
(4)
(5)
(6)
Cross Girder
Bearings
Wearing Coat
*
Rtd. Chief Engineer. (M.P., P.W.D) and a Consultant
**
Design Engineer
26
inadequate assessment of HFL/design flood discharge
and rarely due to structural failure. Due attention to
the determination of hydrology of the structure is to
be paid. An irrational approach can lead to loss &
destruction.
The present bridge is about 6 km upstream of dam
on the same river. Design parameter and special
features for design indicates HFL is at soffit level.
It was not designed for submergence of decking and
water current thrust. The specified design velocity
and design discharge values were on lower side as the
back water effect of dam was not considered. When
flood flows encounter a restriction in the natural
stream, flow adjustments take place in the vicinity
of the restriction i.e. increase in velocity, increase in
scouring of general bed level, afflux etc. A rational
estimation of these parameters leads to economical
design of bridge.
Scour depth governs the depth of foundation, which
must be below scour level. Velocity of flow induces
the moment on the structure. If the velocity of the
stream is high, the moments would be high. Velocity
of natural stream increases at the bridge site due to
obstruction caused by bridge element.
2
DETAILS OF BRIDGE
The details of the submersible bridge (Soffit Level is
at HFL) Drawing No. 1.
: 90.00 m
: 3 spans of 30.00 m, 5.00 m abutment on either side
resting on pile cap & additional RCC returns of 10.00
m length on Right side & 15.00 m length on Left side
with open foundation.
: Prestressed concrete Box structure with overall width
of 8.4 m and roadway of 7.5 m. It was single cell box
with rib thickness of 275 mm at center of the span.
: At quarter spans
: Elastomeric
: RCC Wearing Coat
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
(7)
Parapet wall
: Steel pipe and vertical channel suitable for submersible
bridge.
(8)
Piers
: No separate piers provided the deck is resting on
pedestals which are laid on the pile cap. Pile cap 1.8 m
thick of rectangular shape.
(9)
Piles
: 1.2 m diameter, 4 Nos. piles under each pier & each
abutment. The depth of pile 18.63 m below pile cap.
The pile is designed to be anchored 1.5 m in rock. The
SBC 80 t/m2. It may be soft and weathered rock.
(10) Abutment & RCC returns
: RCC box type abutment with structural RCC approach
slab on the pile foundation/RCC tied back type returns
with counter forts
(11) Formation level
: RL 102.450 m
(12) Soffit level
: RL 100.375 m
(13) H.F.L. (considered in the design of bridge
: RL 100.375 m
(14) L.W.L. (considered in the design of bridge) : RL 98.540 m
(15)
Design velocity (considered in the design
of bridge)
:
1.72 M/sec
(16)
Catchment area/Design discharge taken in
Bridge design
:
425 sq km/1390.24 cumec
The construction of the bridge was completed in
seventeen months and it was opened to traffic. The
bridge has been constructed on the upstream of a dam
on the same river. Dam is at 6 km on the downstream
of said bridge. There is hardly any river joining the
river between the distance of 6.00 km. Dam details
are given in appendix-I. During monsoon it rained
very heavily all over the upper catchments of the
river. The river started flooding at the said bridge site
also, and one gate of the dam was opened. On the next
day rains were continued to be intensive and resulted
further raising of flood and 7 gates of the dams were
opened in the afternoon, during this period about 1800
cumecs discharge were being released from the dam.
At 4.00 pm a crack in deck has been reported by local
residence. One village is situated over the left bank on
downstream started getting submerged.
INDIAN HIGHWAYS, October 2014
The flood level started rising continuously and the
total 13 gates of the dam out of 14 were opened and
about 4090 cumecs discharge had started flowing out
of reservoir through gates. By this time the entire
bridge had been reported to be submerged totally.
The resulting crisis took place in the evening around
8 pm.
3The Bridge AFTER FLOOD
Following Distresses were Observed:
i)
The central pier & two spans resting on it
have collapsed and these are not traceable
anywhere near about. It is not known
whether central piles have collapsed &
flown downstream along with the current.
As shown in photo number 1.
27
28
Drawing 2 Sectional Elevation Showing Obstruction Area Due to Approach Embankement & Bridge Decking
Drawing 1 GAD Followed in Execution of Bridge
TECHNICAL PAPERS
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
4
PROBABLE CAUSES OF DISTRESS
The failure of a bridge structure may occur on account
of any or more of the following reasons:
●
●
●
●
Inadequate
hydraulic
data
and
hydrological investigations.
Deficiencies in geotechnical reports and
assessments.
Deficiencies in Structural design.
Improper construction.
These aspects are examined in details and finding are
elaborated.
Photo No. 1 Collapsed Bridge
ii)
The PSC box structure of one span on
right side bank appears to be intact.
iii)
No cracks on the visible surfaces of end
ribs, soffit slab & deck slab. The concrete
did not appear to be defective.
iv)
There appears to have been a slight tilt
in the pile cap of P1. Corners of the pile
cap have damaged and this may also be
due to collapse of two decks supported
on pile cap.
v)
The Bridge has some brackets & arrestors
to prevent sliding of structure due to water
currents. These are damaged or tilted
badly and this may be due to excessive
thrust resulting from water current on
the submerged deck and collapse of the
deck.
vi)
The box type abutment structure founded
on piles on both side appear slightly tilted
but standing. However the RCC return
units with counter fort resting on soil
with open foundation have collapsed.
vii. Concrete road pavements are provided
in approaches. During flood, the plain
concrete slab in some portion is damaged.
The pitching on side slopes of approaches
provided with PCC blocks have also been
damaged badly. No proper toe wall has
been observed.
INDIAN HIGHWAYS, October 2014
4.1Hydraulic Aspects
The presence of dam was ignored and a submersible
bridge with a length of 90 m was proposed, perhaps
without seeing the bridge/dam site. The effect of
dam 6 km downstream was ignored. The details of
the dam are given in appendix-I. It shows maximum
flood discharge is 1,35,000 cusecs i.e. 3823 cumecs.
The design flood discharge is 1,70,000 cusecs i.e.
4814 m3/sec. After the damage, review of the
geometrical surveys/HFL were conducted and actual
HFL i.e. RL. 103.800 m was worked out. At site, the
left end approach runs along the alignment of bridge
for about 125.00 m length beyond the abutment
and thereafter it is taken to village with nearly
90º turn. From the topography and site observations
this portion of river width beyond present
abutment up to 125.00 m may be regarded as rivers
flow area and the other remaining length of the
X-section with HFL at 103.8000 m is the submergence
portion only. Similarly on right side, with the
presence of higher hilly grounds just upstream and
of downstream of the site the flow zone is limited
to chainage 20-25 m only. Considering the above
effective flow width of the stream and HFL @ 103.800
m, discharge calculations were made (Appendix II).
With this the discharge and velocity of flow through
natural unobstructed stream area works out to 4770 m3/
sec and 3.24 m/sec respectively. When this discharge
passed through 90.00 m length of the bridge, the
velocity at the bridge was excessively high compared
to the design velocity 1.72 m/sec. For the assessment
of the increased velocity, the obstruction area due to
29
TECHNICAL PAPERS
approach embankment, bridge decking and pier etc.
have been worked out and the velocity of flow for a
discharge of 4770 m3/sec with the available net flow
area of 628 m2 works out to 7.38 m/sec (Appendix
II).
4.2
Design Aspects
Design calculations and working drawings of pier
foundations and the abutments are examined and
following observations are made:4.3.1 Details of Pile and Pile Cap for Pier P2
As per the details shown in the above drawing, the
pier foundation consists of group of 4 number bored
cast in situ RCC piles of 1200 mm diameter each with
provision of 1.80 m thick rigid square pile cap of 5.10 m
x 5.10 m at RL. 98.075 m. piles are envisaged to be
taken up to RL. 79.450 m with minimum 1.50 m socket
in rock. No separate pier has been provided and RCC
pedestals to support PSC decking as shown directly
over the RCC pile cap. Piles are shown to be provided
with 27 nos. 20 mm diameter HYSD reinforcement
(≅ 0.75%) and in M-35 grade concrete and the pile cap
is proposed with 16 mm diameter HYSD reinforcement
@ 90 mm c/c both way at bottom as well as at top
faces. 4 piles are arranged in square layout placing
them at 3.60 m c/c apart. As per data given, the
design velocity is 1.72 m/sec at stipulated HFL RL.
100.375 m and formation level is RL. 102.450 m. Thus
as per the above, the foundation was not specified to
be designed to sustain thrust on decking due to water
currents (soffit being at HFL RL. 100.375 m) with a
velocity of 7.381 m/s through the restricted waterway
of 90 m only. Following critical values are worked
out: 30
●
Calculated maximum vertical load on
critical Downstream end pile (i/c self
weight of pile) : 189.70 Ton
●
Calculated maximum bending moment
on RCC section of pile associated
with design maximum vertical load of
176.4 Ton : 88.26T-m
●
Calculated maximum compressive stress
in concrete of pile section under the
combination of above noted maximum
load/moment case : 88.1 Kg/cm2
●
Calculated
maximum
stress
in
reinforcement steel of pile section under
the combination of above noted maximum
load/moments case : 990.3 Kg/cm2
●
Calculated load capacity of pile
with socket of 1.50 m and ultimate
crushing strength of rock as 1000 T/m2
: 274.66 Ton
Geotechnical Aspects
The geotechnical investigation of pier P1, P2 and
abutments A1 A2 shows soft rock. The core recovery
is 60% to 70%. The crushing strength of the rock has
also been obtained and reported to be 1400 tons per m
sq. in one sample. However the safe bearing capacity
is reported to be restricted to only 80 tons per m sq. for
the purpose of design. For actual foundation level the
data about the driving of piles in rock and the depth of
socket in rock has not been reported.
4.3
The above calculated stresses are generally in order
and are within permissible values. In calculation
of pile capacity a higher factor of safety of 7 to the
end bearing component against the stipulated factor
of safety of 5.00 (as per IRC:78-2000) have been
considered, as such the correct calculated pile capacity
will be further more than the designed load.
In view of the specified design parameters the above
pile design is safe.
4.3.2 Details of Abutment & Pile Foundation of
Abutment
As per this drawing a group of 4 number bored cast in
situ RCC piles of 1200 mm dia each are shown for both
abutments A1 & A2. Similar to the pier supports, pile
of abutment structure are also arranged in rectangular
layout. A 1.80 m thick rigid RCC pile cap of 8.40 m
x 5.10 m size is proposed at RL. 98.075 m. RCC box
abutment structure and RCC pedestals supporting
deck span are shown above the pile cap. The proposed
piles of abutments A1 and A2 are considered to be
taken up to 89.000 m and RL. 81.400 m respectively
with minimum socket of 1.50 m in rock.
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
Similar to the case of pier foundations, the calculated
maximum load on critical pile (189.7 Ton) is
observed to be less than the calculated pile capacity.
The calculated maximum stresses in concrete and
reinforcement steel under critical condition with
provision of 24 no. 20 mm dia reinforcement for A1
and 32 no. 20 mm dia reinforcement for A2 have
also been found to be within their permissible limits
of 119.00 Kg/cm2 (for CC M-35) and 2039 Kg/cm2
for Fe 415 grade HYSD bar assessments, the design
calculations are found to be generally in order for the
design data.
However the design data about velocity is wrong.
According the correct data the foundation was under
design and that is why the structure has failed during
floods.
4.4Construction Aspects
At present the structure as it is standing does not show
a substandard quality of concrete.
5MODE OF FAILURE
Based on the observations, the distress is mainly due
to lateral movement of super structure. The probable
cause of this movement is explained below.
Form the study of the topography it appears that,
due to non-release of discharge through dam, flood
started accumulating at upstream side and caused
submergence and spread of flood up to village on
left side. It continued to pass the flow through the
bridge with comparatively moderate velocities and
thus the structure did not fail. But with the situation
of subsequent accumulation of more and more floods
at upstream near bridge, total submergence of bridge
with approaches took place, with rise in water level.
Thereafter sudden release of flow by opening all the
dam’s gates downstream of bridge intensive flows
through the available very small vent area of bridge
caused increased velocity upto 7.381 m/s. This high
velocity water current caused enormous thrust on the
submerged deck. Since the bridge was not designed
for submerged condition and the specified design
velocity was very low (1.72 m/sec only), nominal
RCC arrestor of size 800.00 mm wide & 300.00 mm
INDIAN HIGHWAYS, October 2014
thick at pile cap were inadequate to hold the deck in
position.
These arrestor were not capable of resisting the actual
enormous thrust and failed in shear. Such failure of
arrestor and continued application of horizontal thrust
on deck resulted in dislodging of bridge downstream
(Bridge was simply rested over elastomeric bearing).
This dislodged position of decking might had caused
eccentric loading on pile cap/pile group, which
ultimately resulted in increased vertical loads on two
piles of the group located on downstream side and
reduced loads on the upstream end piles. The increased
load on the pile saddled with huge horizontal force due
to water current thrust form pier & decking resulted in
huge moment on RCC section of the pile. This action
of dislodgement of decking and their shifted position
on pile head might had caused considerable sway in the
foundation comprising of 4 nos. RCC piles & stiff pile
cap (being of large pile length 18.62 m & subjected
to enormous horizontal thrust). Such possible sways
further worsened the situation and resulted in larger
moments in RCC pile section with the same force/
loads. The piles which were not designed to sustain
such large moments/large forces collapsed.
6LESSONS
For the design of any bridge, proper hydrological and
hydraulic investigations and the characteristics of
the Stream/River are of paramount importance. The
Bridge should have been designed and constructed
with due considerations to the following important
parameters:
i)
The HFL/affluxed HFL at the bridge site
must have been decided carefully with
due considerations of the backwater
effect of the existing dam.
ii)
The design velocity assumed arbitrarily
as 1.72 m/s was too low. Structural
designs of the bridge must have been
checked very carefully considering the
submergence and a very high velocity of
7.38 m/sec on account of sudden release
of flood water through the gates of the
dam.
31
TECHNICAL PAPERS
iii)
Construction of approach embankments
in filling caused high obstruction to
natural flow. The rivers causing high
afflux and spread of water should have
been avoided by increasing the bridge
length adequately.
iv) Actual scour depth should be worked
under the effects of backwaters and the
conditions of accelerated flows at narrow
bridge vents due to sudden release of
flood water through the dam gates.
v) The ideal situation is to provide the
approaches of a submersible bridge in
cutting and not in embankment as in the
present case without any return wall.
vi) Back water computations should have
been performed from the dam to the
bridge site and the deck level of the bridge
should have been raised accordingly to
avoid submergence.
vii) For the assessment of various hydraulic
parameters such as discharge, HFL,
afflux, scour depth, design velocity, linear
waterway etc. for the design of bridge
structure at such uncommon location, a
thorough knowledge and experience are
absolutely necessary.
7CONCLUSION
When a bridge is to be constructed upstream of a dam
proper designs of the dam, logical investigations and
hydraulic computations must be performed.
Apart from structural and foundation designs
hydrological and hydraulic analysis e.g. HFL, afflux,
waterway, scour depth should be done.
An afflux 0.15 m, bridge formation level RL.
102.450 m and waterway of 90 m were arbitrarily
fixed without realizing any backwater computations.
Bridge was not designed for submergence of decking
and the actual water current thrust on decking. The
assumed design velocity and design discharge were on
very low side (1.72 m/sec and 1390 m3/Sec) compared
to actual velocity and discharge (7.38 m/sec and
4814 m3/Sec).
APPENDIX - I
Information of Dam at Power House
1
Date of Commencement
:
20/04/1964
2
Date of Completion
:
31/08/1967
3
Width of River
:
350.00 ft.
4
Catchment Area
: 213.58 sq. mile
5
Mean Annual Rainfall
:
6
Maximum
discharge
observed
flood : 1,35,000 cusecs
7
Design flood discharge
: 1,70,000 cusecs
8
Natural river bed level
: (+) 1335.00 ft.
9
Deepest foundation level
: (+) 1313.00 ft.
60 inch
10 Spillway crust level
: (+) 1415.00 ft.
11 Full reserved level
:
12 Maximum flood level
: (+) 1436.00 ft.
13 Road top level
: (+) 1445.00 ft.
14 Total length of Dam
:
1685.00 ft.
15 Length of earthen bank
:
685.00 ft.
16 Maximum depth of water
:
98.00 ft.
32
(+) 1433.ft.
17 Height of Dam
:
110.00 ft.
18 Nos. of Gate
:
14 Nos.
Height of each Gate
:
18.00 ft
Width of each Gate
:
40.00 ft.
Data of Said Bridge
1
Distance dam to bridge by :
road
2
Distance dam to bridge
:
6.00 km (about)
3
At present water width
:
100.00 m (about)
4
Water width observed
: 200.00 m (about) and
5
Formation level of Bridge :
RL. 102.450 m
6
Soffit level
:
RL.100.375m
7
HFL & Width of water
:
RL. 100.375 m &
380.00 m
8
LWL
:
RL. 98.540 m
Note :
10.50 km
Bridge levels given above are with respect to an arbitrary
datum taken near the bridge site without considering the
presence of dam 6km downstream. Hence it should not
be correlated with dam levels.
INDIAN HIGHWAYS, October 2014
TECHNICAL PAPERS
APPENDIX - II
HYDRAULIC CALCULATION
HFL =
RL
103.8
m
Obstructed area is shown in drawing – 2 (as per cross section of river at bridge site given by Department)
Chainage
Ground
Level
Difference Depth Below
Between GL
HFL
Mean
Depth
Length
(m)
Area (m2) A
Perimeter
(m) P
1
2
3
4
5
6
7
8
5
99.035
0
4.765
4.765
0
0
0
0
98.54
0.495
5.26
5.0125
5
25.0625
5.024
10
96.29
2.25
7.51
6.385
10
63.85
10.25
20
91.39
4.9
12.41
9.96
10
99.6
11.136
30
92.04
0.65
11.76
12.085
10
120.85
10.021
40
93.54
1.5
10.26
11.01
10
110.1
10.112
50
96.54
3
7.26
8.76
10
87.6
10.44
60
97.44
0.9
6.36
6.81
10
68.1
10.04
70
97.19
0.25
6.61
6.485
10
64.85
10.003
80
97.74
0.55
6.06
6.335
10
63.35
10.015
90
97.79
0.05
6.01
6.035
10
60.35
10
100
98
0.21
5.8
5.905
10
59.05
10.002
110
98.5
0.5
5.3
5.55
10
55.5
10.012
120
99.385
0.885
4.415
4.8575
10
48.575
10.039
130
99.44
0.055
4.36
4.3875
10
43.875
10
140
99.215
0.225
4.585
4.4725
10
44.725
10.003
150
99.29
0.075
4.51
4.5475
10
45.475
10
160
99.41
0.12
4.39
4.45
10
44.5
10.001
170
99.35
0.06
4.45
4.42
10
44.2
10
180
99.265
0.085
4.535
4.4925
10
44.925
10
190
99.18
0.085
4.62
4.5775
10
45.775
10
200
98.785
0.395
5.015
4.8175
10
48.175
10.008
210
98.77
0.015
5.03
5.0225
10
50.225
10
220
98.38
0.39
5.42
5.225
10
52.25
10.008
INDIAN HIGHWAYS, October 2014
Left
side
Right
side
33
TECHNICAL PAPERS
ΣA =
1390.96
m2 (total flow area without any obstruction)
ΣP =
227.114
m (perimeter of flow area)
S=
0.00093
bed slope
n=
0.03
roughness coefficient
R=
A/P
(wetted perimeter)
6.125 m
velocity through total flow area
V=
(1/n ) R2/3 S1/2
3.4
Q=
m/sec
A X (1/n ) R2/3 S1/2
(total discharge through flow area)
4733.16 m3/s
obstructed area =
a1 =
a1 + a2 + a3
(shaded area)
Area of abutment, return & approach up 270 m
(103.8-average GL from chainage 90 to 200 ) x (200-90)
537.74 m2
a2 =
Projected area of superstructure
Depth of superstructure x Total length of span
2 x 90
=
180.00 m2
a3 =
projected area of pile cap
1.8 x 5.919 x 3
31.96 m2
obstructed area =
a1 + a2 + a3
749.71
available flow area =
m2
1397.96-749.71
(constricted flow area)
641.25 m2
Velocity through constricted flow area
v=
=
34
4733.16/641.25
7.381 m/sec
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
Amendment No. 2/IRC:6-2014/August 2014
To
IRC:6-2014 “Standard Specifications and Code of Practice for Road Bridges,
Section II – Loads and Stresses”
(Revised Edition)
S. No.
4.
Clause No.
For
Read
1.
Item 9 under 1 of Annex B
(Clause No. 202.3)
(Page No. 72)
2.
Item 12 under 1 of Annex B Accidental effects such
(Clause No. 202.3)
as vehicle collision load,
(Page No. 72
barge impact and impact
due to floating bodies
Accidental forces such as vehicle collision
load, barge impact due to floating bodies
and accidental wheel load on mountable
footway
3.
Item 15 under 1 of Annex B Erection Effects
(Clause No 202.3)
(Page No. 72
Construction dead loads such as weight
of launching girder, truss or cantilever
construction equipments
Temperature
including Temperature effects including restraint and
restraint
and
bearing bearing forces
forces
New Clause 204.6 on Fatigue Load
Movement of traffic on bridges causes fluctuating stresses, resulting into possible fatigue damage. The stress
spectrum due to vehicular traffic depends on the composition of traffic, vehicle attributes i.e., gross vehicle
weight, axle spacing and axle load, vehicle spacing, structural configuration of the bridge and dynamic effects.
The truck defined in Fig.1(a) shall be used for the fatigue life assessment of steel, concrete and composite
bridges. The transverse wheel spacing and tyre arrangement of this truck shall be as per Fig. 1(b). 50% of the
impact factors mentioned in Clause 208 shall be applied to this fatigue load.
Fig.1 (a) Fatigue Truck
Fig. 1 (b) Transverse Wheel Spacing and Tyre Arrangement
Fig. 1 Fatigue Load (40T)
INDIAN HIGHWAYS, October 2014
35
Amendment to IRC:6-2014
The stress range resulting from the single passage of the fatigue load along the longitudinal direction of the
bridge, shall be used for fatigue assessment with the fatigue load so positioned as to have worst effect on the
detail or element of the bridge under consideration. The minimum clearance between outer edge of the wheel of
the fatigue vehicle and roadway face of the kerb shall be 150 mm.
For all types of bridges (i.e. Concrete, Steel or Composite ) the fatigue check shall be carried out under frequent
combination of Serviceability Limit State (SLS), with load factors for fatigue load, taken as equal to 1.0. For
design for fatigue limit state, reference shall be made to. IRC:112 for Concrete bridges, IRC:24 for Steel bridges
and IRC:22 for Steel Concrete Composite bridges.
In absence of any specific provision in these codes, following number of cycles may be considered for fatigue
assessment, depending upon the location of the bridge and the category of roads:
a)
The bridges close to areas such as ports, heavy industries and mines and other areas, where generally
heavy vehicles ply shall be designed for the stress induced due to 10 x 106 cycles.
b)
Other bridges shall be designed for the stress induced due to 2 x 106 cycles.
Bridges on rural roads need not be designed for fatigue.
S. No. Clause No.
5.
206.4
For
Read
Each part of the footway shall be
capable of carrying a wheel load of
4 tonne, which shall be deemed to
include impact, distributed over a
contact area of 300 mm in diameter;
the permissible working stress shall
be increased by 25% to meet this
provision. This provision need not be
made where vehicles cannot mount
the footway as in the case of a footway
separated from the roadway by means
of an insurmountable obstacle, such
as, truss or a main girder.
Each part of the footway shall be capable of
resisting an accidental load of 4 tonne, which
shall be deemed to include impact, distributed
over a contact area of 300 mm in diameter. For
working stress approach, the permissible stress
shall be increased by 25% to meet this provision.
For limit state design, the load combination as
per Table 3.2 shall be followed. This provision
need not be made where vehicles cannot mount
the footway as in the case of a footway separated
from the roadway by means of an insurmountable
obstacle, such as, crash barrier, truss or a main
girder.
Note :
A footway kerb shall be considered Note :
mountable by vehicles.
A footway kerb shall be considered mountable by
vehicles.
6.Read Clause No. 214 as under;
214.1Lateral Earth Pressure
Structure designed to retain earth fills shall be proportioned to withstand pressure calculated in accordance with
any rational theory. Coulomb’s theory shall be acceptable for non-cohesive soils. For cohesive soil Coulomb’s
theory is applicable with Bell’s correction. For calculating the earth pressure at rest Rankine’s theory shall be
used.
Earth retaining structures shall, however, be designed to withstand a horizontal pressure not less than that
exerted by a fluid weighing 480 kg/m3 unless special methods are adopted to eliminate earth pressure.
The provisions made under his clause are not applicable for design of reinforced soil structures, diaphragm walls
and sheet piles etc., for which specialist literature shall be referred.
36
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
214.1.1Lateral Earth Pressure under Non-Seismic Condition for Non –Cohesive Soil
214.1.1.1
Active pressure
The coefficient of active earth pressure Ka estimated based on Coulomb earth pressure theory is as follows:
Fig. 214.1.1-1
where,
φ
= angle of internal friction of soil
α
= angle which earth face of the wall makes with the vertical.
β
= slope of earth fill
δ
= angle of friction between the wall and earth fill should be equal to 2/3 of φ subject to maximum
of 22.5º
Point of Application: The centre of pressure exerted by the backfill, when considered dry, is located at an
elevation of 0.42 of the height of the wall above the base and 0.33 of height of wall when considered wet.
214.1.1.2
Passive pressure
The coefficient of passive earth kp is estimated as follows:
Fig. 214.1.1-2
where,
φ
= angle of internal friction of soil
α
= angle which earth face of the wall makes with the vertical.
β
= slope of earthfill
INDIAN HIGHWAYS, October 2014
37
Amendment to IRC:6-2014
δ
= angle of friction between the wall and earth fill should be equal to 2/3 of φ subject to maximum
of 22.5º
Point of Application: The centre of pressure exerted by the backfill is located at an elevation of 0.33 of the
height of the wall above the base, both for wet and dry backfills.
214.1.1.3Live Load Surcharge
A live load surcharge shall be applied on abutments and retaining walls. The increase in horizontal pressure due
to live load surcharge shall be estimated as
∆p = k × γ × heq
where,
k
= coefficient of lateral earth pressure
γ
= density of soil
heq
= Equivalent height of soil for vehicular loading which shall be 1.2 m.
The live load surcharge need not be considered for any earth retaining structure beyond 3 m from edge of
formation width.
214.1.2Lateral Earth Pressure Under Seismic Conditions for Non –Cohesive soil
The pressure from earthfill behind abutments during an earthquake shall be as per the following expression.
214.1.2.1
Active Pressure due to Earthfill
The total dynamic force in kg/m length wall due to dynamic active earth pressure shall be:
(Paw) dyn =
1
wh2 Ca
2
where,
C a
= Coefficient of dynamic active earth pressure
w
= unit weight of soil in kg/m3
h
= height of wall in m, and
214.1.2. (a)
where,
Av
= vertical seismic coefficient
φ
= angle of internal friction of soil
λ
= tan–1
α
= angle which earth face of the wall makes with the vertical
β
= slope of earthfill
δ
= angle of friction between the wall and earthfill, and
38
Ah
1 ± Av
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
Z
, for zone factor Z, refer Table 6 of IRC:6
2
For design purpose, the greater value of Ca shall be taken, out of its two values corresponding to ± Av.
A h
= horizontal seismic coefficient, shall be taken as
Point of application - From the total pressure computed as above subtract the static active pressure obtained by
putting Ah = Av = λ = 0 in the expression given in equation 214.1.2 (a). The remainder is the dynamic increment.
The static component of the total pressure shall be applied at an elevation h/3 above the base of the wall. The
point of application of the dynamic increment shall be assumed to be at mid-height of the wall.
214.1.2.2
Passive Pressure due to Earthfill
The total dynamic force in kg/m length wall due to dynamic Passive earth pressure shall be:
(Ppw)dyn =
1
wh2 Cp
2
where,
C p
= Coefficient of dynamic Passive Earth Pressure
C p
=
214.1.2(b)
w, h, α, φ and β are as defined in (A) above and
Ah
1 ± Av
Point of application – From the static passive pressure obtained by putting αh = ∝v = λ = 0 in the expression
given in equation 214.1.2(b), subtract the total pressure computed as above. The remainder is the dynamic
decrement. The static component of the total pressure shall be applied at an elevation h/3 above the base of the
wall. The point of application of the dynamic decrement shall be assumed to be at an elevation 0.5 h above the
base of the wall.
λ = tan–1
214.1.2.3
Active Pressure due to Uniform Surcharge
The active pressure against the wall due to a uniform surcharge of intensity q per unit area of the inclined
earthfill surface shall be:
(Paq)dyn =
Cp
214.1.2(c)
Point of application - The dynamic increment in active pressures due to uniform surcharge shall be applied at
an elevation of 0.66 h above the base of the wall, while the static component shall be applied at mid-height of
the wall.
214.1.2.4
Passive Pressure due to Uniform Surcharge
The passive pressure against the wall due to a uniform surcharge of intensity q per unit area of the inclined
earthfill shall be:
(Ppq)dyn =
INDIAN HIGHWAYS, October 2014
Cp
214.1.2(d)
39
Amendment to IRC:6-2014
Point of application - The dynamic decrement in passive pressures due to uniform surcharge shall be applied
at an elevation of 0.66 h above the base of the-walls while the static component shall be applied at mid-height
of the wall.
214.1.2.5Effect of Saturation on Lateral Earth Pressure
For submerged earth fill, the dynamic increment (or decrement) in active and passive earth pressure during
earthquakes shall be found from expressions given in 214.1.2 (a) and 214.1.2. (b) above with the following
modifications:
1
a)
The value of δ shall be taken as the value of φ for dry backfill.
2
b) The value of λs shall be taken as follows:
λs = tan–1
Ws
Ah
×
Ws − 1 1 ± A v
214.1.2 (e)
where,
W s
= saturated unit weight of soil in gm/cc,
A h
= horizontal seismic coefficient
Av
= vertical seismic coefficient.
c)
Buoyant unit weight shall be adopted.
d)
From the value of earth pressure found out as above, subtract the value of earth pressure determined
by putting Ah = Av = λs = 0 but using buoyant unit weight. The remainder shall be dynamic
increment.
214.1.3
At-Rest Lateral Earth Pressure Coefficient
The coefficient of at-rest earth pressure shall be taken as
K0 = 1 – sin φ
where,
φ
= angle of internal friction of soil
K 0
= coefficient of earth pressure at-rest
Walls that have of no movement should be designed for “at-rest” earth pressure. Typical examples of such
structures are closed box cell structures.
Point of Application: The centre of pressure exerted by the backfill is located at an elevation of 0.33 of the
height of the wall.
214.1.4
Active and Passive Lateral Earth Pressure Coefficients for cohesive (c – φ) soil – Non
Seismic Condition
The active and passive pressure coefficients (ka and kp) for lateral active and passive earth pressure shall be
calculated based on Coulomb’s formula taking into consideration of wall friction. For cohesive soils, the effect
of ‘c’ shall be added as per procedure given by Bell.
For cohesive soils, active pressure shall be estimated by
Pa = ka γz – 2c K a
40
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
For cohesive soils, passive pressure shall be estimated by
Pp = kp γz + 2c K p
The value of angle of wall friction may be taken as 2/3rd of φ, the angle of repose, subject to limit of 22 ½
degree.
where,
P a
= Active lateral earth pressure
P p
= Passive lateral earth pressure
k a
= Active Coefficient of lateral earth pressure
k p
= Passive Coefficient of lateral earth pressure
γ
= density of soil (For saturated earth fill, saturated unit weight of soil shall be adopted.)
z
= depth below surface of soil
c
= soil cohesive
Point of Application – The centre of earth pressure exerted shall be located at 0.33 of height for triangular
variation of pressure and 0.5 of height for rectangular variation of pressure.
214.1.5
Earth Pressure for Partially Submerged Backfills
The ratio of lateral dynamic increment in active pressure due to backfill to the vertical pressures at various
depths along the height of wall may be taken as shown in Fig. 214.1.5 (a).
The pressure distribution of dynamic increment in active pressures due to backfill may be obtained by multiplying
the vertical effective pressures by the coefficients in Fig. 214.1.5 (b) at corresponding depths.
Fig. 214.1.5 (a)
Distribution of the Ratio =
with height of wall
Note :
Ca is computed as in 214.1.2 (a) for dry (moist) saturated backfills
INDIAN HIGHWAYS, October 2014
41
Amendment to IRC:6-2014
C1a is computed as in 214.1.2 (a) and 214.1.2 (e) for submerged backfills
K1a is the value of Ca when Ah = Av = λ = 0
K1a is the value of C’a when Ah = Av = λ = 0
h1 is the height of submergence above the base of the wall
Lateral dynamic increment due to surcharge multiplying with q is shown in Fig. 214.1.5(b).
2 (Ca – Ka)
cos α
cos(α − i)
2 (Ca1 − K a1 )h
h1
Fig. 214.1.5 (b)
Distribution of the Ratio =
with height of wall
A similar procedure as in 214.1.5 may be utilized for determining the distribution of dynamic decrement in
passive pressures. Concrete or masonry inertia forces due to horizontal and vertical earthquake accelerations are
the products of the weight of wall and the horizontal and vertical seismic coefficients respectively.
214.1.5Earth Pressure for Integral Bridges
For calculation of earth pressure on bridge abutments in internal bridges, the specialist literature shall be
referred.
214.2
No Change
214.3
Design shall be provided for the thorough drainage of backfilling materials by means of weep
holes and crushed rock or gravel drains; or pipe drains, or perforated drains. Where such provisions are not
provided, the hydrostatic pressures shall also be considered for the design.
42
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
214.4
The pressure of submerged soils (not provided with drainage arrangements) shall be considered
as made up of two components:
a)
Pressure due to the earth calculated in accordance with the method laid down in Clause 214.1.1,
unit weight of earth being reduced for buoyancy, and
b)
Full hydrostatic pressure of water
7.Read Table Nos. 3.1 to 3.4 (Page No. 75, to 80 ) are as under:
Table 3.1 Partial Safety Factor for Verification of Equilibrium
Loads
Basic Combination
Accidental Combination
Seismic Combination
Overturning Restoring Overturning Restoring Overturning Restoring
or Sliding or or Resisting or sliding or or Resisting or sliding or or Resisting
uplift Effect
Effect
uplift effect
effect
uplift Effect
effect
(1)
(2)
(3)
(4)
(5)
(6)
(7)
1.1 Dead Load, Snow load (if present),
SIDL except surfacing, Backfill weight,
settlement, creep and shrinkage effect
1.05
0.95
1.0
1.0
1.05
0.95
1.2 Surfacing
1.35
1.0
1.0
1.0
1.35
1.0
1. Permanent Loads:
1.3 Prestress and Secondary effect of
prestress
(Refer Note 5)
1.4 Earth pressure due to Back fill
1.5
-
1.0
-
1.0
-
a) As leading load
1.5
0
0.75
0
-
-
b) As accompanying load
1.15
0
0.2
0
0.2
0
c) Construction live load
1.35
0
1.0
0
1.0
0
a) As leading load
1.5
0
-
-
-
-
b) As accompanying load
0.9
0
0.5
0
0.5
0
a) As leading load
1.5
0
-
-
-
-
b) As accompanying load
0.9
0
-
-
-
-
1.2
0
-
-
-
-
3.1 Vehicle collision (or)
-
-
1.0
-
-
-
3.2 Barge Impact
-
-
1.0
-
-
-
3.3 Impact due to floating bodies
-
-
1.0
-
-
-
(a) During Service
-
-
-
-
1.5
-
(b) During Construction
-
-
-
-
0.75
-
2. Variable Loads:
2.1 Carriageway Live load, associated
loads (braking, tractive and centrifugal) and
pedestrian load
2.2 Thermal Load
2.3 Wind Load
2.4 Live Load Surcharge
accompanying load
effects
as
3. Accidental effects:
4. Seismic Effect
Contd...
INDIAN HIGHWAYS, October 2014
43
Amendment to IRC:6-2014
Loads
Basic Combination
Accidental Combination
Seismic Combination
Overturning Restoring Overturning Restoring Overturning Restoring
or Sliding or or Resisting or sliding or or Resisting or sliding or or Resisting
uplift Effect
Effect
uplift effect
effect
uplift Effect
effect
(1)
(2)
(3)
(4)
(5)
(6)
(7)
a) When density or self weight is well
defined
-
0.9
-
1.0
-
1.0
b) When density or self weight is not well
defined
-
0.8
-
1.0
-
1.0
5.2 Construction Dead Loads (such as Wt.
of launching girder, truss or Cantilever
Construction Equipments)
1.05
0.95
-
-
-
-
a) As leading load
1.5
0
-
-
-
-
b) As accompanying load
1.2
0
-
-
-
-
6.1 Water current forces
1.0
0
1.0
0
1.0
-
6.2 Wave Pressure
1.0
0
1.0
0
1.0
-
-
-
-
1.0
-
1.0
-
-
1.0
-
5. Construction Condition:
5.1 Counter Weights:
5.3 Wind Load
6. Hydraulic Loads: (Accompanying Load):
6.3 Hydrodynamic effect
6.4 Buoyancy
1.0
Clause No
For
Read
Note 4 under Wind load and thermal load need not be Wind load and thermal load need not be taken
Table 3.1
taken simultaneously.
simultaneously unless otherwise required to cater
for local climatic condition,
Table 3.2 Partial Safety Factor for Verification of Structural Strength
Loads
Ultimate Limit State
Basic
Combination
Accidental
Combination
Seismic
Combination
(2)
(3)
(4)
a) Adding to the effect of variable loads
1.35
1.0
1.35
b) Relieving the effect of variable loads
1.0
1.0
1.0
a) Adding to the effect of variable loads
1.75
1.0
1.75
b) Relieving the effect of variable loads
1.0
1.0
1.0
(1)
1. Permanent Loads:
1.1 Dead Load, Snow load (if present), SIDL except
surfacing
1.2 Surfacing
Contd...
44
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
Loads
(1)
Ultimate Limit State
Basic
Combination
Accidental
Combination
Seismic
Combination
(2)
(3)
(4)
1.3 Prestress and Secondary effect of prestress
1.4 Back fill Weight
(Refer Note 2)
1.5
1.0
1.0
a) Adding to the effect of variable loads
1.5
1.0
1.5
b) Relieving the effect of variable loads
1.0
1.0
1.0
a) As leading load
1.5
0.75
-
b) As accompanying load
1.15
0.2
0.2
c) Construction live load
1.35
1.0
1.0
a) As leading load
1.5
-
-
b) As accompanying load
0.9
-
-
2.3 Live Load Surcharge effects (as accompanying load)
1.2
0.2
0.2
2.4 Construction Dead Loads (such as Wt. of launching
girder, truss or Cantilever Construction Equipments)
1.35
1.0
1.35
3.1 Vehicle collision (or)
-
1.0
-
3.2 Barge Impact (or)
-
1.0
-
3.3 Impact due to floating bodies
-
1.0
-
(a) During Service
-
-
1.5
(b) During Construction
-
-
0.75
5.1 Water current forces
1.0
1.0
1.0
5.2 Wave Pressure
1.0
1.0
1.0
-
-
1.0
0.15
0.15
1.0
1.5 Earth Pressure due to Backfill
2. Variable Loads:
2.1 Carriageway Live load and associated loads (braking,
tractive and centrifugal) and Footway live load
2.2 Wind Load during service and construction
3. Accidental effects:
4. Seismic Effect
5. Hydraulic Loads (Accompanying Load):
5.3 Hydrodynamic effect
5.4 Buoyancy
INDIAN HIGHWAYS, October 2014
45
Amendment to IRC:6-2014
Table 3.3 Partial Safety Factor for Verification of Serviceability Limit State
Loads
Rare
Combination
Frequent
Combination
Quasi-permanent
Combination
(1)
(2)
(3)
(4)
1.1 Dead Load, Snow load if present, SIDL except
surfacing
1.0
1.0
1.0
a) Adding to the effect of variable loads
1.2
1.2
1.2
b) Relieving the effect of variable loads
1.0
1.0
1.0
1.3 Earth Pressure Due to Back fill weight
1.0
1.0
1.0
1. Permanent Loads:
1.2 surfacing
1.4 Prestress and Secondary Effect of prestress
1.5 Shrinkage and Creep Effect
(Refer Note 4)
1.0
1.0
1.0
a) Adding to the permanent loads
1.0
1.0
1.0
b) Opposing the permanent loads
0
0
0
a) Leading Load
1.0
0.75
-
b) Accompanying Load
0.75
0.2
0
a) Leading Load
1.0
0.60
-
b) Accompanying Load
0.60
0.50
0.5
a) Leading Load
1.0
0.60
-
b) Accompanying Load
0.60
0.50
0
3.4 Live Load surcharge as accompanying load
0.80
0
0
4.1 Water Current
1.0
1.0
-
4.2 Wave Pressure
1.0
1.0
-
4.3 Buoyancy
0.15
0.15
0.15
2. Settlement Effects
3. Variable Loads:
3.1 Carriageway load and associated loads (braking,
tractive and centrifugal forces) and footway live load
3.2 Thermal Load
3.3 Wind Load
4. Hydraulic Loads (Accompanying loads) :
Clause No
Note 3under Table 3.3
46
For
Read
Wind load and thermal load need not Wind load and thermal load need not be taken
be taken simultaneously.
simultaneously unless otherwise required to
cater for local climatic condition,
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
Table 3.4 Partial Safety Factor for Checking the Base Pressure and Design of Foundation
Loads
Combination Combination
(1)
(2)
Seismic
Combination
Accidental
Combination
(1)
(2)
(3)
(4)
(5)
1.1 Dead Load, Snow load (if present), SIDL except
surfacing and Back Fill
1.35
1.0
1.35
1.0
1.2 SIDL surfacing
1.75
1.0
1.75
1.0
1. Permanent Loads:
1.3 Prestress Effect
1.4 Settlement Effect
(Refer Note 4)
1.0 or 0
1.0 or 0
1.0 or 0
1.0 or 0
a) Adding to the effect of variable loads
1.50
1.30
-
-
b) Relieving the effect of variable loads
1.0
0.85
1.0
1.0
a) Leading Load
1.5
1.3
b) Accompanying Load
1.15
1.0
0.2
0.2
2.2 Thermal Load as accompanying load
0.90
0.80
0.5
0.5
a) Leading Load
1.5
1.3
-
b) Accompanying Load
0.9
0.8
0
0
2.4 Live Load surcharge as Accompanying Load (if
applicable)
1.2
1.0
0.2
0.2
a) During Service
-
-
1.5
1.0
b) During Construction
-
-
0.75
0.5
1.35
1.0
1.0
1.0
5.1 Water Current
1.0 or 0
1.0 or 0
1.0 or 0
5.2 Wave Pressure
1.0 or 0
1.0 or 0
1.0 or 0
-
-
1.0 or 0
a) For Base Pressure
1.0
1.0
1.0
b) For Structural Design
0.15
0.15
0.15
1.5 Earth Pressure due to Backfill
2. Variable Loads:
2.1 All carriageway loads and associated loads
(braking, tractive and centrifugal) and footway live
load
0.75 (if
0.75 (if
applicable) or 0 applicable) or 0
2.3 Wind Load
3. Accidental Effect or Seismic Effect
4. Construction Dead Loads (such as Wt. of
launching girder, truss or Cantilever Construction
Equipments)
5. Hydraulic Loads:
5.3 Hydrodynamic effect
6. Buoyancy:
INDIAN HIGHWAYS, October 2014
47
Amendment to IRC:6-2014
Clause No
For
Read
Note 3 under Wind load and thermal load need not be taken Wind load and thermal load need not be taken
Table 3.4
simultaneously.
simultaneously unless otherwise required to
cater for local climatic condition.
Note 9 under At present the combination of loads shown in
Table 3.4
Table 3.4 shall be used for structural design
of foundation only. For checking the base
pressure under foundation unfactored loads
shall be used. Table 3.4 shall be used for
checking of base pressure under foundation
only when relevant material safety factor and
resistance factor are introduced in IRC:78.
At present the combination of loads shown in
Table 3.4 shall be used for structural design of
foundation only. For checking the base pressure
under foundation, load combination given in
IRC:78 shall be used. Table 3.4 shall be used
for checking of base pressure under foundation
only when relevant material safety factor and
resistance factor are introduced in IRC:78.
8.Read Table No. 9 is under:
Table 9 Response Reduction Factors
For
Bridge Component
Superstructure
Read
‘R’ with
Ductile
Detailing
2.0
‘R’
Bridge Component
without
Ductile
Detailing
NA
‘R’ with
‘R’ without
Ductile Ductile Detailing
Detailing (for Bridges in
Zone II only)
a) Superstructure of integral/Semi integral
bridge/Framed bridges
b) Other types of Superstructure, including
precast segmental constructions
2.0
1.0
1.0
1.0
Substructure
Substructure
(i) Masonry/PCC Piers, Abutments
-
1.0
(i) Masonry/PCC Piers, Abutments
-
1.5
(ii) RCC short plate piers where
plastic hinge can not develop
in direction of length & RCC
abutments
3.0
2.5
(ii) RCC wall piers and abutments
transverse direction (where plastic hinge
can not develop)
-
1.0
(iii) RCC long piers where hinges
can develop
4.0
3.3
(iii) RCC wall piers and abutments in
longitudinal direction (where hinges can
develop)
3.0
2.5
(iv) Column
4.0
3.3
(iv) RCC Single Column
3.0
2.5
(v) Beams of RCC portal frames
supporting bearings
1.0
1.0
(v) RCC/PSC Frames
a) Column
4.0
3.0
b) RCC beam
3.0
2.0
b) PSC beam
1.0
1.0
(vi) Steel Framed Construction
3.0
2.5
(vii) Steel Cantilever Pier
1.5
1.0
2.0
2.0
Bearings and Connections (see note v
also)
1.0
1.0
Bearings
48
INDIAN HIGHWAYS, October 2014
Amendment to IRC:6-2014
For
Bridge Component
Connectors & Stoppers (Reaction
Blocks)
Those
restraining
dislodgement or drifting away of
bridge elements.
Read
‘R’ with
Ductile
Detailing
‘R’
Bridge Component
without
Ductile
Detailing
‘R’ with
‘R’ without
Ductile Ductile Detailing
Detailing (for Bridges in
Zone II only)
When connectors and Stoppers (Reaction Blocks) Those
stoppers are designed restraining dislodgement or drifting away
to withstand seismic of bridge elements. (See Note (vi) also)
forces primarily, R
value shall be taken as
1.0. When connectors
and
stoppers
are
designed as additional
safety measures in
the event of failure
of bearings, R value
specified in Table
9 for appropriate
substructure shall be
adopted.
1.0
1.0
S. No.
Clause No.
For
Read
9.
Notes below Table 9
(i)
No change
(219.5.5)
(ii)
No change
(iii)
No change
Nil
(iv) Ductile detailing is mandatory for piers of
bridges located in seismic zones III, IV and V and
when adopted for bridges in seismic zone II, for
which “R value with ductile detailing” as given in
Table 9 shall be used.
Nil
(v) Bearings and connections shall be designed
to resist the lesser of the following forces, i.e., (a)
design seismic forces obtained by using the response
reduction factors given in Table 9 and (b) forces
developed due to over strength moment when hinge
is formed in the substructure
Nil
(vi) When connectors and stoppers are designed as
additional safety measures in the event of failure of
bearings, R value specified in Table 9 for appropriate
substructure shall be adopted.
For design of foundation, the
seismic loads should be taken as
1.25 times the forces transmitted
to it by substructure, so as to
provide sufficient margin to
cover the possible higher forces
transmitted
by
substructure
arising out of its over strength.
For design of foundation, the seismic loads should be
taken as 1.35 and 1.25 times the forces transmitted to
it by concrete and steel substructure respectively, so
as to provide sufficient margin to cover the possible
higher forces transmitted by substructure arising
out of its over strength. However, the dynamic
increment of earth pressure due to seismic need not
be enhanced.
10.
219.8
INDIAN HIGHWAYS, October 2014
49
Amendment to IRC:112-2011
Amendment No. 2/IRC:112-2011/August, 2014
To
IRC:112-2011 “Code of Practice for Concrete Road Bridges”
S. No. Clause No.
& Page No
1.
6.4.2.7
Table 6.9
(Page 47)
Age at
loading
to(days)
For
Read
Table 6.9 Final Creep Coefficient
[φ (70 yr)] of Concrete at age of t = 70 years.
Table 6.9 Final Creep Coefficient
[φ (70 yr)] of Concrete at age of t = 70 years
Notional Size 2Ac/u (in mm)
50
150
600
Dry atmospheric
conditions (RH-50%)
50
150
600
Humid atmospheric
conditions (RH-80%)
Age at
loading
to (days)
Notional Size 2Ac/u (in mm)
50
150
600
Dry atmospheric
conditions (RH-50%)
50
150
600
Humid atmospheric
conditions (RH-80%)
1
5.50
4.60
3.70
3.60
3.20
2.90
1
6.00
4.95
4.05
3.95
3.50
3.15
7
5.50
4.60
3.70
2.60
2.30
2.00
7
4.20
3.45
2.85
2.75
2.45
2.20
28
3.90
3.10
2.60
1.90
1.70
1.50
28
3.20
2.65
2.20
2.10
1.90
1.70
90
3.00
2.50
2.00
1.50
1.40
1.20
90
2.60
2.10
1.75
1.75
1.50
1.35
365
1.80
1.50
1.20
1.10
1.00
1.00
365
2.00
1.60
1.30
1.30
1.15
1.05
Note :
1.
2.
2.
The above table is applicable for M35 grade concrete. For
lower grades of concrete the coefficients may be multiplied
by
45
f cm
For higher grades of concrete the coefficient may be
worked out using equations given in Annexure A-2.
10.2.2.2(2)
Fig 10.4
(Page 84)
Fig. 10.4 Shear Components of Increased Tension in
Bonded Prestressing Tendons and Forces in Chord
Members Inclined w.r.t. Axis of the Element
Fig. 10.4 Shear Component for Members with Inclined Chords
3.
10.2.3(3)
& (4)
(Page 84
and 85)
3 In the elements of variable depth, where VEd’ MEd’ and NEd
are concurrently acting forces, the design shear force VEd from
sectional analysis shall be reduced by the favourable contribution
from any inclined compression chord, tension chord and inclined
prestressing tendons in case of bonded tendons as shown in
Fig. 10.4. Any unfavourable contributions, depending on
direction of inclination of chords and the prestressing tendons
shall be added to VEd, in Fig. 10.4, VNS = VEd – Vpd – Vccd – Vtd
with appropriate signs.
4.
10.3.1
(Page 85)
VRd - The shear resistance of a member with shear VRd - The shear resistance of a member with shear
reinforcement = VRdS + Vccd + Vtd
reinforcement = Minimum of (VRds; VRd.max) + Vccd + Vtd
50
3 In the elements of variable depth, where VEd, MEd and NEd
are concurrently acting forces, the design shear force VEd from
sectional analysis shall be reduced by the favourable contribution
from any inclined compression chord and tension chord as
shown in Fig. 10.4. Any unfavourable contributions, depending
on direction of inclination of chords, shall be added to VEd. In
Fig. 10.4, VNS = VEd – Vccd – Vtd .
INDIAN HIGHWAYS, October 2014
Amendment to IRC:112-2011
5.
10.3.3
(Page 90)
Members requiring design shear reinforcement
Members requiring design shear reinforcement (VRdc < VED)
6.
10.3.3.2
(Page 90)
For members with vertical shear reinforcement the shear For members with vertical shear reinforcement, the shear
resistance VRd is the smaller value of ..
resistance is the smaller value of …...
7.
10.5.2.1(4) T /T
+ VEd/VRdmax < 1.0
Ed Rdmax
Eq. 10.47
V
is
the
design
transvers force
Ed
(Page 108)
TEd/TRdmax + VNs/VRdmax < 1.0
8.
16.5.4 (1) In certain cases, (e.g. clear cover to main reinforcement being
(Page 180) larger than 50 mm and in webs) it may be necessary to provide
surface reinforcement, either to control cracking or to ensure
adequate resistance to spalling of the cover.
In certain cases, (e.g. clear cover to main reinforcement being
larger than 75 mm and in webs) it may be necessary to provide
surface reinforcement, either to control cracking or to ensure
adequate resistance to spalling of the cover.
9.
17.1 (6) Where longitudinal reinforcement is curtailed (e.g. in tall piers) Where longitudinal reinforcement is curtailed potential of
(Page 192) potential of formation of hinge shall be avoided just beyond the formation of hinge shall be avoided just beyond the point of
point of curtailment.
curtailment. Not more than 1/3 of longitudinal reinforcement
available at the section shall be curtailed.
Errata to IRC:112-2011
Errata No. 3/IRC:112-2011/August, 2014
To
IRC:112-2011 “Code of Practice for Concrete Road Bridges”
S. No. Clause No. &
Page No.
For
Read
1.
10.3.3.3(8)
Fig. 10.6
(Page 93)
2.
11.3.2.2(4)
(Page 116)
C = 10 (π2)
C =10 (≈ π2)
3.
18.8.9(1)
(Page 228)
2nd line
Clause 18.8.8(4)
Clause 18.8.8(3)
4.
Annexure-A2
Eq-A2-27
(Page 239)
βRH = 1.55
INDIAN HIGHWAYS, October 2014
βRH = 1.55
51
Amendment to IRC:81-1997
Amendment No. 1/IRC:81-1997/August, 2014
To
IRC:81-1997 “Guidelines for Strengthening of Flexible Road Pavements
Using Benkelman Beam Deflection Technique” (First Revision)
S. No.
Clause No. &
Page No.
1.
7.5
(Page 20)
2.
Annexure 1
Calculations
S. No. (5)
(Page 22)
For
Read
From structural considerations, the From structural considerations, the
recommended minimum bituminous recommended minimum bituminous
overlay thickness is 50 mm bituminous overlay thickness is 40 mm.
macadam with an additional surfacing
course of 50 mm DBM or 40 mm
bituminous concrete.
The rebound deflection (%) (i.e. col. 9 of Delete the sentence.
Table 3) shall be the twice of the XT
value.
Errata to IRC:37-2012
Errata No. 1/IRC:37-2012/August, 2014
To
IRC:37-2012 “Tentative Guidelines for the Design of Flexible Pavements”
S. No. Clause No. &
Page No.
1.
52
6.5.2
(Page 16)
(Eq. 6.6)
For
Read
A. Fatigue Life in Terms of Standard
Axles
A. Fatigue Life in Terms of Standard
Axles
12
 (11300/E.0804 +191 
N = RF 

εt


12
 (113000/E 0.804 +191 
N = RF 

εt


INDIAN HIGHWAYS, October 2014
Ministry of Road Transport & Highways Circulars
Contd...
INDIAN HIGHWAYS, October 2014
53
Contd...
54
INDIAN HIGHWAYS, October 2014
Contd...
INDIAN HIGHWAYS, October 2014
55
Circulars and Annexures are available on Ministery’s Website (www.morth.nic.in) and same are also available in Ministery’s Library.
56
INDIAN HIGHWAYS, October 2014
Just Released
The following IRC Publications were released during the 203rd Council Meeting of
IRC on 19th August, 2014:
S. No.
Code No.
Title of the Publication
Price (Rs.)
Postage (Rs.)
1.
IRC:83-2014 (Pt. IV)
Standard Specifications and Code of Practice for
Road Bridges Section-IX Bearings (Spherical and
Cylindrical)
600.00
40.00
2.
IRC:116-2014
Specifications for Readymade Bituminous Pothole
Patching Mix using Cut-Back Bitumen
400.00
30.00
3.
IRC:SP:42-2014
Guidelines of Road Drainage (First Revision)
800.00
40.00
4.
IRC:SP:49-2014
Guidelines for the use of Dry Lean Concrete as Sub-Base
for Rigid Pavement” (First Revision)
400.00
30.00
5.
IRC:SP:84-2014
Manual of Specifications & Standards for Four Laning
of Highways through Public Private Partnership (First
Revision)
1000.00
50.00
6.
IRC:SP:101-2014
Interim Guidelines for Warm Mix Asphalt
600.00
30.00
7.
IRC:SP:102-2014
Guidelines for Design and Construction of Reinforced
Soil Walls
800.00
40.00
Above publications can be purchased on line through IRC website www.irc.org.in or from office
of Indian Roads Congress, Jamnagar House, Shahjahan Road, New Delhi-110011 or Kama
Koti Marg, R.K. Puram, New Delhi-110022. For further inquiry please contact Tel No. 23386274
E-mail: [email protected].
ANNOUNCEMENT
Sales Centre of IRC Publications is being operational at Tripura State Centre, Agartala (Tripura West)
from 20th July, 2013. This is a collaboration as IRC endeavor to enhance its reach to the Engineering
Fraternity.
The esteem members of IRC in Eastern Region are requested to take advantage of this new initiative.
The contact address of Sales Centre of IRC Publications is the Institution of Engineers (India),
Tripura State Centre, Pandit Nehru Complex, Gurkhabasti, Agartala, Tripura (West), Pin- 799006,
Tel: (0381) 2304700.
INDIAN HIGHWAYS, October 2014
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INDIAN HIGHWAYS, October 2014
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INDIAN HIGHWAYS, October 2014