The P2P Initiative:
Performance-based Specs for Concrete
NRMCA Continuing Education Series
© National Ready Mixed Concrete Association
All rights reserved
Announcement
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This program is registered with the AIA/CES for
continuing professional education. As such, it does
not include content that may be deemed or construed
to be an approval or endorsement by the AIA of any
material of construction or any method or manner of
handling, using, distributing, or dealing in any material
or product.
Introduction
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Continuing education for engineers and architects
Length of Presentation: 1 Hour
Architects Earn 1 LU
Engineers Earn 1 PDH
NRMCA is an AIA/CES Registered Provider
Records kept on file with NRMCA and AIA/CES Records
Outline
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What is the P2P Initiative?
What is a Prescriptive Specification?
What is a Performance Specification?
What are the Benefits of P2P?
What Activities are Underway?
How to Specify Concrete using Current Codes?
What is the P2P Initiative?
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Stands for Prescription-to-Performance
Initiative of the ready mixed industry through the NRMCA
Coordinated by P2P Steering Committee under the
NRMCA Research, Engineering and Standards
Committee
Members include technical representatives, product
suppliers, contractors, engineers, and architects
Why Performance?
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Shifting Expertise to Concrete Producers
Reduce Conflicts in Specifications
Identify Roles and Responsibilities
Controlling Construction Cost (through optimization)
Meet Greater Demands on the Product (through
innovation)
Improving Quality Systems
Training and Certification Programs
Construction Cost Savings of P2P
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Innovative construction means and methods
Improved construction schedules
More efficient structural designs
Simplified specifications and submittal process
Optimized mix designs
Innovative Technologies
High-Performance Concrete
High-Strength Concrete
Self- Consolidating Concrete
Improved Quality Systems
Testing Labs
Product Development
Material Handling
NRMCA Training and Certifications
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Plant and Truck Certification
Plant Manager Certification
Concrete Technologist Certifications
Certified Delivery Professional (drivers)
Concrete Certified Sales Professional
Under development
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Concrete technologist responsible for performance mixes
Concrete producer certification based on quality system
P2P Goals
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Allow performance specifications as an alternative to current
prescriptive specifications
Leverage expertise of all parties to improve quality and reliability of
concrete construction
Assist architects/engineers to address concrete specifications in
terms of functional requirements
Allow flexibility on the details of concrete mixtures and construction
means and methods
Better establish roles and responsibilities based on expertise
Continue to elevate the performance level of the ready mixed
concrete industry
Foster innovation and advance new technology at a faster pace
What is a Prescriptive Specification?
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Details mixture proportions and construction means and
methods
Do not always cover intended performance
May conflict with intended performance
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Example: Low w/c for durability could increase thermal and
shrinkage cracking
Requirements are generally not directly enforceable
Producer held responsible for performance and defects,
even though he lacks the freedom to make changes
Prevents mixture optimization for performance
No incentive for quality control / batch uniformity
Prescriptive Specification
Intended Performance
 Placing/Finishing
 Strength
 Min Shrinkage
 Resistance To:
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Freeze-Thaw
Corrosion
Sulfate attack
ASR
Cracking
Abrasion
Prescriptive Criteria
 Slump
 Max w/cm ratio
 Min cement content
 Min/max air
 Min/Max pozzolans/slag
 Blended cements
 Aggregate grading
 Source Limitations
 Chloride Limits
Prescriptive Specification
Intended Performance
 Placing/Finishing
 Strength
 Min Shrinkage
 Resistance To:
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Freeze-Thaw
Corrosion
Sulfate attack
ASR
Cracking
Abrasion
Prescriptive Criteria
 Slump
 Max w/cm ratio
 Min cement content
 Min/max air
 Min/Max pozzolans/slag
 Blended cements
 Aggregate grading
 Source Limitations
 Chloride Limits
Some prescriptive criteria are required by code but
many are not
Prescriptive Specification Example
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w/c ratio = 0.40
Min. cement = 600 pcy
Strength = 3500 psi
No SCM
Aggregate grading 8 – 18%
No reactive aggregate
Low alkali cement
Shrinkage = 0.04% max
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No cracking
No curling
Slump 5 ± 1 inch
Setting time 4 ± 0.5 hrs
Max temp 85° F
Impermeable
Uniform color
Example: Water Cement Ratio
Air
Air
Water
Paste
Water
Cement
Cement
Compressive Strength, psi
w/cm alone does not control strength
8000
Mix 1
7000
Mix 2
6000
Mix 3
5000
4000
3000
2000
1000
0
0.40
0.45
0.5
0.55
0.6
0.70
Water-Cementitious Ratio (w/cm)
Source: ACI 211
Charge Passed, Coulombs
w/cm alone does not control permeability
8000
Portland cement
7000
SCM1
SCM2
6000
Ternary Blend
5000
4000
3000
2000
1000
0
0.70
0.55
0.45
Water-Cementitious Ratio (w/cm)
Source: ACI 232, 233, 234
What is a Performance Specification?
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Performance requirements of concrete
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Focus on performance and function
Assignment of responsibility
Flexibility to adjust mixture ingredients and proportions to
achieve consistent performance
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Hardened state for Service (meeting owner’s requirements)
Plastic state for Constructability (meeting the contractor’s
requirements)
Changes in weather conditions
Changes in materials
Measurable and enforceable
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Defined test methods and acceptance criteria
How would it work?
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Qualification requirements would be established for
producers
Performance criteria would be specified by the A/E
Contractor would partner with producer to establish
constructability criteria
Submittal will demonstrate compliance with specified
requirements
Compliance through pre-qualification tests and limited
jobsite acceptance tests
Who Benefits from P2P?
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Owners
Engineers/Architects
Concrete Contractors
Concrete Producers
Benefits to Owners from P2P
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Improved quality
Improved performance
Reduced construction time
Reduced cost
Higher confidence in concrete construction
Innovative solutions
Benefits to Engineers/Architects
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Focus on function rather than composition
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Simplified submittal review
Improved product consistency
Reduced conflict with contractor/producer
Reduced risk
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Strength, Durability, Shrinkage, etc.
Producer responsible for concrete mix design
Innovative solutions
Benefits to the Contractors
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Improved communication / coordination
Constructability requirements addressed
Predictable performance
Innovate on construction means and methods
Benefits to Concrete Producers
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Eliminates conflicts in specifications
Improved clarity in what needs to be furnished
Encourages innovation
Rewards investment in quality control
Allows optimization of mixtures for performance
Allows adjustment of materials/proportions to
compensate for changes in materials and weather
Provide innovative products
What are the Challenges?
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Acceptance of Change
Trust / Credibility
Knowledge Level (training)
Reference Codes and Specifications
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Prescriptive limitations
Measurement and Testing
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Reliability of existing tests
Reliability of jobsite tests
What Activities are Underway?
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Communication
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Engineers, Architects, Contractors, and Producers
Articles and presentations
Developing Producer Quality System / Qualifications
Developing Model Spec / Code Revisions
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Look at model codes from other countries (Canada, Europe, Australia)
 Look at similar initiatives in the US (FHWA and DOTs)
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Documenting Case Studies
Conducting Research
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Test Methods for Performance
 Quantifying differences between prescriptive and performance mixes
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Delivering Training Programs
How to Specify Concrete Using Current Codes
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Objective: Minimize prescriptive requirements
Comply with ACI 318 Chapter 3, 4 and 5
Example: 3 story concrete building with first level parking
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Structural slabs, beams, and columns
Slabs-on-grade (parking)
Foundation walls
Footings
Freezing and thawing (with deicing chemicals)
Soils contain sulfates (severe)
Unusual to have freeze-thaw and sulfate exposure
Items in Yellow are comments
Most concrete does not require prescriptive criteria
Classes of Concrete for the Project
Class
Application
Exposure
Strength, f’c
1
Slabs and beams
None
4,000 psi
2
Columns
None
5,000 psi
3
Slabs on grade,
Foundation walls
Freeze/Thaw,
Deicing Chemicals,
Sulfate (severe)
4,500 psi
4
Footings
Sulfate (severe)
4,500 psi
Class 1 and 2 strength is governed by structural design requirements
Class 3 and 4 strength is governed by durability requirements
Part 1 - General
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1.1
1.2
1.3
1.4
1.5
1.6
RELATED DOCUMENTS
SUMMARY
DEFINITIONS
SUBMITTALS
QUALITY ASSURANCE
DELIVERY, STORAGE, AND HANDLING
Submittals
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Submit field or laboratory test records for each class of
concrete to demonstrate concrete will meet:
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Required average compressive strength
Other specified requirements in section 2.12
Test data should meet the following requirements
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Test data from concrete supplied from the same production
facilities proposed for the work
Test data from concrete mixtures containing similar materials
proposed for the work
Submittals (cont’d)
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Submit properties of mix design for each class of concrete including:
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Specified compressive strength, ƒ΄c
Documentation of strength test results indicating the standard deviation
Required average compressive strength, ƒ΄cr
Average compressive strength of proposed mixture
Placement method
Slump or slump flow
Air content
Density
w/cm ratio
Maximum aggregate size
Sources and designations of ingredient materials
Some properties will be specified and others will be selected by
producer and contractor
Slump is one example. Slump should not be specified but selected
by the contractor and producer since this is means and methods
Submittals (cont’d)
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Submit documentation indicating installer, manufacturer,
and testing agency meet the qualifications specified in
Section 1.5 Quality Assurance.
Quality Assurance
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Installer Qualifications:
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On-site supervisor of the finishing crew who qualified as ACI Certified
Concrete Flatwork Technician for flatwork placing and finishing.
Flatwork finisher certification is important for constructing slabs
General standard of care of concrete construction is addressed in
this certification program
Quality Assurance (cont’d)
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Manufacturer Qualifications:
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NRMCA Certified Ready Mixed Concrete Production Facility
NRMCA Concrete Technologist Level 2
NRMCA certified concrete production facilities demonstrate
compliance with requirements of ASTM C 94
Includes an annual certification of delivery vehicles
The NRMCA Concrete Technologist Level 2 Certification validates
personnel’s knowledge of fundamentals of concrete technology
including mixture proportioning.
Certification is obtained by passing a 90 minute exam administered
by NRMCA with ACI Grade 1 Field Testing Technician Certification
as the prerequisite.
Details available at www.nrmca.org/certifications .
Quality Assurance (cont’d)
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Testing Agency Qualifications:
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Meet the requirements of ASTM C 1077.
Field testing: ACI Concrete Field Testing Technician Grade I.
Lab testing: ACI Concrete Strength Testing Technician or ACI Concrete
Laboratory Testing Technician – Grade I.
Test results for the purpose of acceptance shall be certified by a
registered design professional employed with the Testing Agency.
Concrete testing is very sensitive to the way specimens are
collected, cured, and tested. Proper field and lab procedures are
essential to achieving meaningful results.
Quality Assurance (cont’d)
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Pre Installation Conference:
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Require representatives of each entity directly concerned with cast-inplace concrete to attend, including:
 Architect
 Structural Engineer
 Contractor
 Installer (Concrete Contractor)
 Pumping Contractor
 Manufacturer (Ready-mixed concrete producer)
 Independent testing agency
NRMCA and American Society of Concrete Contractors has a
document titled Checklist for the Concrete Pre-Construction
Conference that can be used as a guide
Part 2 - Products
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2.1 MANUFACTURERS
2.2 FORMING MATERIALS
2.3 STEEL REINFORCEMENT
2.4 REINFORCEMENT ACCESSORIES
2.5 CONCRETE MATERIALS
2.6 WATERSTOPS
2.7 VAPOR RETARDERS
2.8 FLOOR AND SLAB TREATEMENTS
2.9 CURING MATERIALS
2.10 RELATED MATERIALS
2.11 REPAIR MATERIALS
2.12 CONCRETE MIXTURES
Concrete Materials
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Cementitious Materials:
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Use materials meeting the following requirements with limitations
specified in Section 2.12.
 Hydraulic Cement: ASTM C 150 or ASTM C 1157 or ASTM C 595
 Fly Ash: ASTM C 618
 Slag: ASTM C 989
 Silica Fume: ASTM C 1240
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Avoid listing brand names for most materials in this section if a
standard for the product already exists.
Many existing standards are performance-based.
Avoid limiting the type or quantities of cementitious materials that
can be used unless required for certain performance attributes as
listed in Section 2.12 Concrete Mixtures.
Concrete Materials (cont’d)
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Normalweight Aggregate: ASTM C 33
Water: ASTM C 1602
Fibers: ASTM C 1116
Concrete Materials (cont’d)
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Chemical Admixtures:
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Air Entraining: ASTM C 260
Water reducing, accelerating and retarding: ASTM C 494
Admixtures for flowing concrete: ASTM C 1017
Admixtures with no standard designation shall be used only with the
permission of the design professional when its use for specific
properties is required.
Avoid limiting the type of admixtures that can be used unless there
is a specific reason (eg. Chloride based admixtures for corrosion).
Consider specifying or allowing the use of admixtures which do not
have a specific ASTM designation with appropriate documentation
indicating beneficial use to concrete properties.
These include colors, viscosity modifying admixtures, hydration
stabilizing admixtures, pumping aids, anti-freeze admixtures, etc.
Concrete Mixtures
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Prepare design mixtures for each class of concrete on
the basis of field test data or laboratory trial mixtures, or
both according to ACI 318, Chapter 5.
Design mixtures shall meet the requirements listed in
Table 2.12.
Concrete Mixtures (cont’d)
Table 2.12 Concrete Mixtures
Exp.
ƒ΄c
Nom.
Max.
Agg.
Size1
1
Slabs and
beams
None
4,000
psi
3/4”
N/A2
2
Columns
None
5,000
psi
3/4”
N/A2
3
Slabs on
grade,
Foundation
walls
Freeze/Thaw,
Deicing
Chemicals,
Sulfate
(severe)
4,500
psi
Footings
Sulfate
(severe)
4,500
psi
Class
App.
4
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Air
Content
1-1/2”
5-1/2 %3
1-1/2”
N/A2
Max.
w/cm
by
weight
Cementitious
Materials
Admix.
Max. water
sol. Cl ion in
conc., % by
wt of cement
N/A
See section
2.5 A
See
section
2.5 D
1.00
N/A
See section
2.5 A
See
section
2.5 D
1.00
0.45
Limits on
cement4,
No calcium
fly ash, slag,
chloride
and silica
admixtures
5
fume
0.45
Limits on
hydraulic
cement4
No calcium
chloride
admixtures
Provide a schedule of concrete classes of the structure including a
description of exposure.
Provide limits on materials based on Chapter 3 and 4 of ACI 318
0.15
0.30
Concrete Mixtures (cont’d)
Table 2.12 Concrete Mixtures
Class
App.
Exp.
ƒ΄c
Nom.
Max.
Agg.
Size1
1
Slabs
and
beams
None
4,000 psi
3/4”
N/A2
N/A
See section See section
2.5 A
2.5 D
1.00
2
Columns
None
5,000 psi
3/4”
N/A2
N/A
See section See section
2.5 A
2.5 D
1.00
Air
Content
Max.
w/cm by
weight
Cementitious
Materials
Admix.
Max. water
sol. Cl ion in
conc., % by
wt of cement
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Few limits on materials for class 1 and 2 since durability is not a concern
 No maximum water-cement ratio or minimum cement content
 Compressive strength based on structural design requirements
 Maximum aggregate size controlled by ACI 318 – 3.3 Aggregates
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1/5 narrowest dimension of forms
 1/3 slab depth
 3/4 minimum clear spacing between reinforcement (governs)
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Maximum chloride ions controlled by ACI 318 – 4.4 for corrosion protection
of reinforcement that will be dry or protected from moisture in service
Concrete Mixtures (cont’d)
Table 2.12 Concrete Mixtures
Class
App.
Freeze/Thaw,
Slabs on
Deicing
grade
Chemicals,
Foundation
Sulfate
walls
(severe)
3
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ƒ΄c
4,500
psi
1-1/2”
Air
Content
5-1/2
%3
Max.
w/cm
by
weight
Cementitious
Materials
Admix.
Max. water
sol. Cl ion in
conc., % by
wt of cement
0.45
Limits on
cement4,
fly ash,
slag, and
silica
fume5
No calcium
chloride
admixtures
0.15
Class 3 concrete is exposed to freeze-thaw, deicing chemicals, and severe sulfates
Compressive strength, air content, maximum w/cm based on ACI 318 4.2 Freezing
and thawing exposure.
Limits on SCMs based on ACI 318 4.2.3 for concrete exposed to deicing chemicals:
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Exp.
Nom.
Max.
Agg.
Size1
Fly ash, 25% max
Slag, 50% max
Silica fume, 10% max
Total of fly ash, slag, and silica fume, 50% max
Total of fly ash and silica fume, 35% max
Limits on cement type, calcium chloride admixtures, strength, and w/cm are based on
ACI 318 4.3 Sulfate exposure.
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Type V cement must be used
Concrete Mixtures (cont’d)
Table 2.12 Concrete Mixtures
Class
App.
Exp.
ƒ΄c
Nom.
Max.
Agg.
Size1
4
Footings
Sulfate
(severe)
4,500
psi
1-1/2”
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Air
Content
Max.
w/cm by
weight
Cementitious
Materials
Admix.
Max. water
sol. Cl ion in
conc., % by
wt of cement
N/A2
0.45
Limits on
cement4
No calcium
chloride
admixtures
0.30
Class 4 concrete is exposed to severe sulfates
Compressive strength, cement type, maximum w/cm, and restriction
on using calcium chloride admixtures are based on ACI 318 4.3 –
Sulfate exposure
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Type V cement must be used
PART 3 - Execution
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3.1 FORMWORK
3.2 EMBEDDED ITEMS
3.3 REMOVING AND REUSING FORMS
3.4 SHORES AND RESHORES
3.5 VAPOR RETARDERS
3.6 STEEL REINFORCEMENT
3.7 JOINTS
3.8 WATERSTOPS
3.9 CONCRETE PLACEMENT
3.10 FINISHING FORMED SURFACES
3.11 FINISHING FLOORS AND SLABS
3.12 MISCELLANEOUS CONCRETE ITEMS
3.13 CONCRETE PROTECTING AND CURING
3.14 LIQUID FLOOR TREATEMENTS
3.15 JOINT FILLING
3.16 CONCRETE SURFACE REPAIRS
3.17 FIELD QUALITY ASSURANCE
Concrete Placement
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Measure, batch, mix, deliver, and provide delivery ticket
for each batch of concrete in accordance with ASTM C
94.
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Do not add water to concrete during delivery or during
placement.
Water is permitted to be added to a batch of concrete at the
project site before placement of the batch begins provided that
the amount of water added does not exceed the allowed amount
indicated on the delivery ticket.
Field Quality Assurance
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Testing: Owner shall engage a qualified testing agency
to perform concrete field tests and prepare test reports.
Concrete Field Tests:
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Concrete Test Samples: Samples for concrete tests shall be
taken in accordance with ASTM C 172.
Field Quality Assurance (cont’d)
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Compressive Strength Tests on concrete:
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Samples shall be taken not less than once per day,
nor less than once for each 150 yd3 of concrete,
nor less than once for each 5000 ft2 surface area for slabs or walls.
Acceptance based on standard cured cylinders in accordance with
ASTM C 31 and tested at 28 days in accordance with ASTM C 39.
Strength test results are the average of two specimens.
Tests of slump, air content, temperature and density shall be made
and recorded with the strength test results.
Consider testing at 56 or 90 days for high volumes of SCMs.
Average of two cylinders represent a strength test result by ACI 318
If a 7 day test is specified for informational purposes (not acceptance),
clearly indicate that in the specification.
The installer and manufacturer may choose to make additional cylinders for
field cured specimens to monitor early age strength for form removal and
reshoring.
Field cured specimens are typically not recognized for acceptance.
Field Quality Assurance (cont’d)
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Strength of each concrete class shall be deemed
satisfactory:
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The average of three consecutive compressive-strength tests
equals or exceeds specified compressive strength
Any individual compressive-strength test result does not fall
below specified compressive strength by more than 500 psi.
When compressive strength tests indicate low strength,
follow procedure in ACI 318 chapter 5.6.4 Investigation
of low-strength test results
Field Quality Assurance (cont’d)
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Air Content: ASTM C 231.
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Air content tests shall be performed on concrete at least at the same
frequency as compressive strength testing.
The provisions of ASTM C 94 shall apply for acceptance of air content
of concrete.
Only use air content as an acceptance criterion if there is an air
content requirement
ACI 318 establishes an air content tolerance of ±1.5%
ASTM C 94 permits a jobsite adjustment if the air content is low
Allows for retesting prior to rejecting concrete
Field Quality Assurance (cont’d)
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Slump: ASTM C 143; one test when concrete is sampled
for strength tests.
Temperature: ASTM C 1064; one test when concrete is
sampled for strength tests.
Density: ASTM C 138; one test when concrete is
sampled for strength tests.
Test results shall be reported to architect, engineer,
concrete producer, and concrete contractor within 48
hours of testing.
Recap
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Comply with ACI 318
Place limits on materials in concrete based on the
exposure of the concrete.
Plan to propose changes to ACI 318 Chapter 4 –
Durability Requirements to allow performance-based
alternatives
Plan to develop model performance-based specifications
based on the new provisions
Additional Information
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Visit www.nrmca.org/P2P
Download Example Specification
Download P2P Articles
Download Research Studies