MICROFINE CEMENT GROUTS & APPLICATIONS IN GROUTING PRACTICE Dr. A. V. SHROFF Professor Emeritus, M. S. UNIVERSITY OF BARODA. CWC Lecture at Madras 25-03-2015 1 Scope of Presentation Design & Characterization of Micro fine cement grouts under static and dynamic loadings. Applications of Micro fine Cement grouts at projects. 2 Need for Microfine Cements Suspension grouts, prepared conventionally with ordinary Portland cement, can be successfully injected into gravels and coarse sands. Chemical grouts can permeate fine sands and coarse silts, but they are expensive and pose environmental and health problems. As an alternative to chemical grouting of fine sands & coarse silts, the use of grouts prepared with microfine cements has been proposed. The first microfine cement available commercially was MC-500, manufactured by Onoda Cement Corporation in Japan. 3 Microfine Cement Definitions ACI Committee 552, Geotechnical Cement Grouting, defines microfine cement as a material in which dmax <15 μm (Perretet al., 2000). According to the European Standard for grouting (SFS-EN 12715), microfine cements are characterized by a specific surface area >800 m2/kg and d95 <20 μm. The Norwegian proposal divides two groups of microcements: d95 <30 μm, microfine cement and d95 <15 μm,ultrafine cement (Tolpannen& Syrjanen, 2003). In U.K. practice, ultrafine cements are characterized 4 by dmax ≤ 6μm (Littlejohn, 2003). Composition of Suspensions Water to Cement (W/C) Ratio (by weight): Thick suspensions (W/C →0.7:1 -<2:1) Thin suspensions (W/C →2:1 –12:1 in research) (W/C →2:1 –4:1 in applications) Admixtures :superplasticizers (their use is necessary for fluidity increase, according to Bremen, 1997 & Saada, 2003), dispersants, retarders, accelerators Additives : bentonite (improves stability), slag, silica fume, sodium silicate, fly ash 5 KIND OF SOIL MicrofineCement grouts COHESIVE SOIL GROUTED FORM FRACTURING SANDY SOIL PERMEATION GRAVEL BOUNDARIES INCREASE BEARING STRENGTH PREVENT HEAVING ROOFING PREVENT SETTLEMENT SEAL WATER ENSURE AIR TIGHTNESS PREVENT SEEPAGE 6 Specific Applications Water sealing of dam bottom ducts Water sealing of reservoir bottoms Underground oil storage facilities Preventing seepage of embankments on polder dikes Preventing seepage in reclaimed land Preventing liquefaction of sandy soil 7 Specific Applications Curtain grouting for Dams and embankments Ensuring leak tightness of retention dikes around oil tank Stabilization and sealing of work faces in shield tunneling and pipe insertion work Water sealing of joints on water and sewage mains Water sealing of tunnel walls 8 Specific Applications Preventing settlement of roads and embankments to be constructed on weak ground Preventing heaving and boiling inside cofferdams Stabilization of soil in zones susceptible to landslides Remedying and preventing differential settlement of oil tanks Fixation and water sealing in fractured zone during tunnel construction 9 Applications of MC Grouts 10 APPLICATIONS DEPENDING UPON FRACTURING IN THE ROCK NEAR SURFACE AT FOUNDATION BED, SHALLOW BLANKET GROUT IS PLACED , THROUGH WHICH A DEEP CURTAIN GROUT IS INJECTED . CUTOFF IS EXTENSION OF CORE. NO SEEPAGE PATH SHOULD BE AT INTERFACE, AS IT IS CRICAL. IN EMBANKMENT DAM WITH EARTH, USUAL POSITION RANGE FROM A VERTICAL CURTAIN AT AXIS TO STEEPLY INCLINED ON ECOMMENCEING 1/3 OF THE WAY BETWEEN THE AXIS & U/S TOE OF THE DAM CURTAIN AT FACED ROCKFILL DAM MAY COMMENCE FROM U/S TOE & RANGE FROM A VERTICAL TOE AN INCLINED ORIENTATION. IN GRAVITY DAM ,DRAINAGE & CURTAIN HOLES ARE COMMONLY DRILLED FROM GALLERY WITHIN THE DAM AT AN ARCH DAM THE CURTAIN MUST PASS THROUGH THAT PART OF THE FOUNDATION WHICH REMAINS MORE OR LESS COMPRESSED DURING THE FLEXURE CYCLE OF THE DAM CLAY CORE WALL 6-12M EMBANKMENT DAM- EARTH CORE BLNKET GROUTING ROCK FILL DAM WITH CONCRETELINED FACE DEEP GROUT CURTAIN CONCRETE GRAVITY DAM WITH INTERSECTING FAULT ZONE CONCRETE ARCH DAM CONVENTIONAL CLOSURE PATTERN FOR DRILLING & GROUTING WITH SEQUENCE 11 APPLICATIONS Microfine cement m +sodium silicate grout Fan array from successive heading Fan array from successive heading or from pit is designed for grouting of rock fissures in crown portion, preventing raveling down of siltsand during box jacking or tunnel shielding operation as well as for making crown impervious under heavy seepage Vertical parallel array of grout holes are used to eliminate problems of settlement of structures during tunnel operation for subways or Micro fine tube railway . Cement+ Staggered array of grout holes rows Sodium Surface street level & fan hole from silicate within the tunnel downward to grout strengthen the soil in-between tunnel bottom & top of sub ways Parallel array from surface Inclined array of grout holes from pit Micro fine grouts 12 Staggered array of grout holes Functions of Grouting Grout Grout pipe Permeation Grout Grout pipe Compaction Grout Grout pipe Hydro fracturing 13 Pore volume/pore size reduction of sand due to MC grouting Interaction with formation 14 Grouts Classification • Engineering Classification: (based on grout characteristics & engineering performance • Rheological Classification d/dt = (1/ )(0 - p) Binghamian: Compressive/ Triaxial strength kPa d/dt = (1/ )0 ST Newtonian Binghamian Yield value (p) Shear stress ( dyn/ cm2) Viscosity cps Rate of shear d/dt Sec-1 Newtonian: 0.1 ZD LI IT 1 Time (Days) 10 100 15 Laboratory testing set-ups 1 2 Computerized Brookfield Rheometer Time-viscosity and time-strength relationship of cement, chemical and cement based chemical grouts facilitates initial flow and strength to resist foundation stresses and washout forces Servo-loop Material Testing System 1-Load unit 2- control unit Load –deflection, t-strength curves 16 through load cell and transducers Laboratory test set ups-Physical properties (a) Marsh cone - fluidity measurement afflux time (b) Mud balance for sp.gravity measurement (c) Bleeding test under pressure for stability measurement (d) Water- retentivity meter for squeezed water measurement (e) Horizontal flow meter for fluidity measurement (f) Capillary viscometer for viscosity measurement (g) Bleeding potential measurement of variable depth of clear water above sedimented cement flocs (h) Washout test for the measurement of threshold gradient (Adherent strength) 17 Physical properties of MC grouts W:C Ratio Physical Properties Specific Gravity Gel Time min Water retentivity, s Bleeding Potential Marsh cone viscosity 50 ml 100 ml % second 0.8 1.38 10 28 NM Nil 31 1 1.19 13 24 NM 3% 28.5 2 1.14 180 18 49 8% 27.5 5 1.02 345 11 38 54% 27 NM: Not Measurable 18 INJECTION DEVICE Column diameter: 2.2 –51 cm Column length: 0.3 –18 m !!! 19 Device for Spherical Injections The injection funnel represents 1/33 of a sphere and enables penetration depths of approximately 75 cm. 20 Laboratory Injections Aims: •Injectability documentation •Effectiveness determination •Grouted soil design parameters (static & dynamic loading) 21 GRAVEL SAND FINE COARSE 0.006 mm 0.075 mm 0.425 mm 2 mm 4.75 mm Penetrability of grouts w.r.t. formation material COARSE SILT MEDIUM Towards 0.002 mm SILT (NON PLASTIC) FINE CEMENT D15/d85 should be between 5-24, BENTONITE D-soil,d-grout Rock fissure size ≥ 3d, d-cement<0.1D10 POLYURETHANE AND POLYACRYLAMIDE SILICATES – HIGH CONCENTRATION SILICATES – LOW CONCENTRATION D15/d85 > 40 AMINOPLAST PHENOPLASTS ACRYLATES For Microfine cement grout (Shroff, Joshi-02) ACRYLAMIDE MICRO FINE CEMENT GROUT 22 Development of grouts - Micro fine cement grouts MICRO FINE CEMENT GROUTS POSSESS HIGH STRENGTH, DURABILITY & PENETRATION CAPABILITY COMPARABLE TO CHEMICAL GROUTS WHICH ELIMINATE TOXIC HEZARDS MICRO GROUTS MC helper (dispersants): 1% Naphthalene sulphonate- Gr I 1%Sulphonated melamine Formaldehyde- GrII, III & IV GROUP-2 Slag+ Chemical activators ROH,R2CO3,R2S,R2F- (0.1%) Silica salts of R2O.(n)SiO2 type where ‘ R’ is alkali metal ion Na, K or Li GROUP-3 MC-III + Chemical activators (0.02 to 1%)as mentioned above (i) Specific Surface area 9000 (cm2/g) (ii) 50 percent grain size About 4 (μm) 100 % finer (cumulative vol %) GROUP-1 Slag+ Portland Cement (As Activator) MC-I:25% slag+75% OPC MC-II: 50% slag+50% OPC MC-III:75% slag+25% OPC Fineness GROUP-4 MC-III+ Sodium silicate (20,40,60,80%) MC-III+Bentonite(1,2&3%) MC-III+ Silica fume(4,12,20%) 90 80 70 60 MC MCD-I MCD-II OPC(53 grade) OPC(43 grade) OPC(33 grade) 50 40 30 20 10 0 0.1 1 10 Particle size, mm x 10-3 100 1000 Fig-3.2 Particle size distribution curves of different cements from laser particle size analyser LASER PARTICLE SIZE ANALYZER CHEMICAL COMPOSITION OF MCIII GROUTS Oxides Ca O Sio2 Al2O3 Fe2O3 Mg O SO3 % 49.2 29 13.2 1.2 5.6 1.2 1g Loss 23 0.3 Development of grouts :Time- Viscosity of micro fine cement Trace amount of Na F in MCIII & Slag give low initial viscosity, controlled gel time, high permeation & Low bleeding tends to solid mass at set time MCIII with Sodium silicate in presence of 3% phosphoric acid proved to be best grout within ideal frame work compared to OPC, MCD & other slag based grouts with activators & Silica fume. GROUP 1 G R O U P 2 MC-I MCII MCI-25 %SLAG+ 75%OPC, MCII-50%SLAG + 50%C MCIII + SODIUM SILICATE-20,40,60,80% MCIII +60% SODIUM SILICATE WITH PAPHOSPHORIC ACID G R O U P 3 ONLY SLAG + ACTIVATORS- 0.1 % MC III( 25% S+ 75%C) ACTIVATORS .1% MCIII+BENTONITE-1,2, & 3% G R O U P MCIII+ SILICA FUME- 4, 12, 20 % 4 B-BENTONITE SF- SILICA FUME 24 Development of cement & slag Tri axial compression, UCS, Grouts : Indirect Tensile & Flexural SLAG+REACTANT MCIII+REACTANT strength 8000 UNCONFINED COMPRESSIVE STRENGTH MCIII+SILICA FUME MC-III D E I A kPa MCIII+SS MC-II W/S=0.8 %SS=40 28DAYS STRENGTH 7OOO V 6000 T 5000 O R MC-I MCIII+BENT. Ơ3=0 ơ3=98 KPA Ơ3=196 KPA 4000 S T R E s 2000 s MCD 3000 OPC 1000 0 0 1 2 3 4 % AXIAL STRAIN MCIII+ REC. TYPICAL STRESS-STRAIN CURVE OF RAW MC- SS GROUT SLAG+ REC. MC-III TRIAXIAL COMPRESSION TEST MCD OPC MCIII+SS MCIII+SF INDIRECT/FLEXURAL TENSILE STRENGTH MC-III MCIII+ BENT. MC-II MC-I OPC MCD MCD FAILED SAMPLES OF RAW MC- BENTONITE & MC-SILICAFUME ,UCS& TRIAXIAL TESTS Amongst cement & slag based grouts, MCIII (75% slag + 25% OPC )+Silica Fume grout with w:s ratio 2 show highest deviator stress 8.2 M Pa with failure strain 4.66 % having maximum cohesion 750 kPa & =610 with confining stress 196.2 kPa at 28days. Slag & MCIII with reactants 0.1% Na F (Sodium Fluoride) display best raw unconfined compressive strength of 15 Mpa & Strength of grouted sand with these grouts show 7.32 Mpa. Adherent washout grouted sand Strength=6.83Mpa 25 Also above grouts give highest indirect tensile 4.12 MPa & flexural strength 6.83 MPa of grouted sand at 28 days. Creep measurement of Cement & MC Grouted sand 26 Creep Study : MC-SS & MC Grouted Sand Creep of MC grouted sand increases Up to 42 days but the rate of increase diminishes with progress of time. The creep of MC-SS grouted sand is more compared to that of MC grouted sand. Creep of MC or MC grouted sand is 3to 6 fold that of ordinary concrete / mortar( cement –sand grout) Cement based suspension grouts Exhibits low creep &most durable 27 material among grouts Cyclic Plate Load Test: Natural & MC Grouted Sand Barken method of Natural Frequency of foundation- soil system = √ CuA/ m, m=Weight of machine & foundation, A= contact area foundation &soil, Cu = coefficient of elastic uniform compression Ultimate load intensity obtained from load settlement curve of MC (W:C =5) grouted sand @ 28 days is 50 kpa which is 4.67 & 5.33 times in dry sand & 30 % saturated sand respectively. After 10 cycles, in cyclic pile load test at 14 days Ei, Eh & coefficient of elastic uniform compression (Cu) increased 1.31, 1.21 & 1.44 times respectively Ei, Eh, before grouting = 44 28 & 77 kPa/mm ; Cu=65200kN/cubic meter Settlement Damages due to liquefaction Liquefaction Saturated Sandy Soil without or with fines Loss of Shear Strength Reduced Effected Stress Increased Pore Water Pressure Earthquake forces give rise to liquefaction in soil that causes heavy structure to sink substantially in to the ground or tilt excessively and light weight structure to float upwards. The enormous damage to number of Civil engineering structures in Kutch earthquake set classical examples of earthquake induced liquefaction. 29 Liquefaction Study – Microfine Cement Based Grouts 5 4 2 3 1 1 Loading frame 2 Pressure panel 3 Servo control measuring unit 4 six channel oscillograph & two channel synchroscope 5 Actuator Samples prepared by dry pluviation or compaction -temping Standard vibration tri axial compression testing machine SAMPLE- BEFORE & AFTER FAILURE Consolidated undrained tri axial cyclic compression tests are performed TYPICAL TIME HISTORY OF CYCLIC LOADING Initial liquefaction occurs when the Value of pore pressure, generated in saturated sand undergoing cyclic undrained load ,momentarily equals confining stress and effective stress becomes zero. The strains during each following Cycle become larger with increase in cycles In pure uniform sand under high ‘ƒ’ & C R R, pore pressure increased Suddenly, reached 1 quickly, leading to liquefaction while MC-grouted mass took long time 210 s & MS-SS 30 350 s to reach initial liquefaction 0.75 0.65 | | | | | | | UNSAFE | | | | | 0.55 0.45 UNSAFE 20 40 30 Liquefaction Study – Microfine Cement Based Grouts In thin grouts (w:c = 10 to 5 ) with 1 to 3% Bentonite, CRR = 0.65to 0.50 while at and above w:c = 2, CRR = 0 7to 0.85, virgin sand RD = 0.3, CRR = 0.2 at Ni = 30 At 30 cycles CRR value of MC-SS grouted sand are above 0.6 at 1 day which is within safe limit of liquefaction. It is three times than pure sand. 31 Design of Grouted Factor of Safety of a Soil at Gandhidham – Hospital Building Site (after earth quake) Input data: moderately stiff uniform fine sand deposit. Earthquake magnitude: 6.5, Seismic Energy source: 0.5km, amax peak = 0.998m/sec2 (from local seismic station), = 20.2kN/m3, depth from GL (z) = 5 mt, Sd = 1- 0.00765 z (Tyoud 2001) = 0.9617, Induced CSR = 0.65(amax/g)(o/o’)Sd ,o = h = 101 kPa, o’ = w h =51kPa, Induced CSR = 0.65*(0.998/9.81)*(101/51)*0.9617 = 0.1259 CRR from cyclic Tri axial test on virgin sand= 0.251at equivalent cycle 8.33, applying correction factor=0.642, CRR corrected=0.251x0.642=0.161, F= CRR/CSR= 0.161/0.1259= 1.28 which is low, which is required to be increased To increase FS of soil grouted with MCSS with w:c = 5 and SS = 20%, CRR (at one day) = 0.81 at 8.33 cycles (above figure) applying same correction factor Cr = 0.642, CRRc = 0.642*0.81 = 0.52, so, FS = 32 0.52/0.1259 = 4.1( Increase in FS 8 times) Alccofine MicroMaterials Stands With The Test Of Time 34 Alccofine Plant- Goa Flash Dryer MILL SILO AQP – Particle size Distribution Alccofine1101 Sr. Particle size distribution AQP Results of Alccofine1101 1. D10 < 2.5µ 1.3 2. D50 <6µ 5 3. D90 <12µ 10.6 4. D100 <26µ 20 Why Alccofine? We provide customized products as per site working conditions Open time is high as considering a delay in over all grouting purpose Customization can be done with respect to fineness , W/c ratio required for grouting , strength criteria if any ( feasible of cement based grouts) and setting time. Have tieup with applicators and Global Contractors Exporting materials to Canada, Australia, Indonesia and many more countries Customization of packing if any required based on total quantity required Technical support and on site support for our customers. 38
© Copyright 2024