WATER PERMEABILITY, POROSITY AND COMPRESSIVE · widely used to represent the strength of hardened...

WATER PERMEABILITY,POROSITY AND COMPRESSIVE

STRENGTH OF HIGHPERFORMANCE CONCRETE

1K.V. Pratap, 2K.Venkatesh,3Sk. Enthiyaz, 4M. Sumi, 5Y. Ratnasiri

1,2 Asst.Prof,Narasaraopeta Engineering College (Autonomous),

Narasaraopet, A.P.3Student, M.Tech (Structural Engineering),

Narasaraopeta Engineering College (Autonomous),Narasaraopet, A.P.

4Student, M.Tech (Transportation Engineering),Priyadarshini institute of technology

and science for women, Tenali5Student, M.Tech (Structural Engineering),

A.M. Reddy memorial College of Engineeringand Technology, Narasaraopet, A.P.

June 21, 2018

Abstract

Water permeability and porosity of concrete is used toindicate its durability. Accurate measurement of waterpermeability and porosity is difficult and it becomes moredifficult as the grade of concrete increases. While testingHigh Performance Concrete (HPC) specimens, thesedifficulties become even more difficult. HPC is used widely

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International Journal of Pure and Applied MathematicsVolume 120 No. 6 2018, 4193-4209ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

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to improve the durability and performance characteristicsof structures. In this paper, the water permeability ofnormal concrete M20 grade including HPC of M80 gradeare measured using three-cell permeability apparatus.Ordinary Portland Cement (OPC) is partially replaced (byweight) with 5%, 10% and 15% Metakaolin and Silicafume, water cement ratio of 0.3 was maintained. k-Permeability, n- Porosity, fck- Compressive strength.

Keywords:Compressive strength, HPC, Metakaolin,Porosity, Silica fume, Water permeability.

1 INTRODUCTION

Many recent innovations in advanced concrete technology havemade it possible to produce concrete with exceptionalperformance characteristics. High Performance Concrete isdefined as concrete, which meets special performance anduniformity requirements that cannot always be achieved by usingonly conventional materials and normal mixing, placing andcuring practices. The requirements may involve enhancements ofplacement and compaction without segregation, long-termmechanical properties, early-age strength, toughness, volumestability, durability and service life under severe environmentalexposure conditions.

Testing of concrete is an important factor for finding out itsstrength. Generally the 28-days strength is the most reliable andwidely used to represent the strength of hardened concrete. HighPerformance Concrete can be obtained by using very low ratios ofwater to cementitious materials (w/c < 0.35), high cementitiouscontents (> 450kg/m3) and with Supplementary cementingmaterials (SCM), such as Metakaolin, silica fume and the use ofhigh dosages of super plasticizer.

The durability of concrete structures is always a factor to beconsidered in aggressive environments. In the case of structureswhich are continuously in contact with water like offshorestructures, parking decks and Dams the penetration of water isthe major factor which controls the durability of the structure.Therefore, permeability and the pore system of the concrete arecritical to the durability of the structure. The results obtained

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here are on strength, Permeability and porosity of concrete usingmetakaolin and silica fume as cement replacing material.

2 OBJECTIVE OF THE PRESENT

WORK

In the present study, Accelerated Curing (”A.C”) (by Boilingwater method confining to Indian Standard: 9013-1978) is usedfor determining Permeability (’k’)(confining to IndianStandard:3085-1965) and Porosity(’n’)(confining to ASTM C642);Normal Curing(”N.C”) and Accelerated Curing is used fordetermining Compressive strength(’fck’). Based on theexperimentally obtained results, relations are formulated betweenPermeability vs. Compressive strength and Permeability vs.Porosity. It is found that the incorporation of 10% Metakaolin ascement replacement yielded the optimum strength, permeabilityand porosity values, for silica fume it is at 15%.

3 EXPERIMENTAL STUDIES

A. MATERIALSOrdinary Portland cement confining to Indian Standard:8112-1989, Metakaolin and Silica fume are used. Super plasticizerof modified polycarboxylic ether GLENIUM B233 is used. Fineaggregate of zone II sand confining to Indian Standard: 383-1970and coarse aggregate of 12.5mm are used.

B. MIX PROPORTIONSMetakaolin and Silica fume at 5%, 10% and 15% (by weight) isincorporated as partial replacement of cement. Water cement ratioof 0.3 is maintained for all the mixes. Slump value is maintainedbetween 150mm to 200mm. The mix design is done by using Aitcinmethod and composition is listed in table 1.

C. DETAILS OF MIX-1In this mix 5%, 10% and 15% cement was replaced by Metakaolin,keeping water/binder ratio same and the mixes named as MK-05,MK-10 and MK-15.

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D. DETAILS OF MIX-2In this mix 5%, 10% and 15% cement was replaced by Silica Fume,keeping water/binder ratio same and the mixes named as SF-05,SF-10 and SF-15.

4 WORK PLAN

The work plan followed is shown in the table 4.

5 RESULTS AND DISCUSSIONS

A. GENERALExperimental studies have been undertaken to evaluate thecompressive strength, permeability and porosity of HPC usingdifferent mineral admixtures. The test methods are followedaccordingly as described in Chapter 5.

B. COMPARISION OF COMPRESSIVE STRENGTHCompressive strength test was carried on HPC with differentmineral admixtures (Metakaolin and Silica Fume) by using bothNWC and ACT separately. The specimens were tested and theirresults are shown in Table 5.

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The 150 x 150 x 150 mm cubes were tested for compression testunder uniaxial compression after 28 days period of normal watercuring, the 150 x 150 x 150 mm cubes were tested for compressivestrength test under uniaxial compression after curing in acceleratedcuring tank.

From fig 5 it is observed that compressive strength obtained byusing MK is more compared to SF by using NWC. But whereas,the % achievement of compressive strength by using ACT is morefor SF than that of MK.

C. PERMEABILITY STUDYPermeability test was carried on HPC with different mineraladmixtures (Metakaolin and Silica Fume). The specimens weretested and their permeability results are shown in Table 6.

The 150 x 150 x 150 mm cubes were cured by using ACT andwere tested by using three cell permeability apparatus.

From fig 2 it is observed that, for MK low value of permeabilityis obtained at 10

D. Correlation between permeability and compressive strength

k = A(fck)2 + B(fck) + CWhere k and fck are permeability (150 mm cube) and compressive

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Figure 1: Comparison of compressive strength between NWC vs.ACT

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Figure 2: Variation of Permeability

strength (150 mm cube) of concrete respectively. A, B and C arecoefficients that can be obtained from the regression analysis.

E. Permeability vs. Compressive strength study for MKreplacement levelsThe relationship between permeability and compressive strengthof concrete were shown in fig 3 and 4 by using NWC and ACTrespectively.

From fig 3 and 4, it was observed that there was a considerablyhigh relationship between permeability and compressive strengthof the concrete so that regression analysis provided correlationcoefficient (R2) of 0.99 and 1 for NWC and ACT respectively.

From fig 5 it was observed that for MK at 10% replacementboth compressive strength and permeability are optimised.

F. Permeability vs. Compressive strength study for SFreplacement levelsThe relationship between permeability and compressive strengthof concrete were shown in fig 6 and 7 by using NWC and ACTrespectively.

From fig 6 and 7, it was observed that there was a considerablyhigh relationship between permeability and compressive strengthof the concrete so that regression analysis provided correlationcoefficient (R2) of 1 and 0.99 for NWC and ACT respectively.

From fig 8 it was observed that for SF at 15% replacement both

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Figure 3: Permeability vs. Compressive strength for MKreplacement levels by using NWC

Figure 4: Permeability vs. Compressive strength for MKreplacement levels by using ACT

Figure 5: Variation of k and fck with MK replacement levels

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Figure 6: Permeability vs. Compressive strength for SFreplacement levels by using NWC

Figure 7: Permeability vs. Compressive strength for SFreplacement levels by using ACT

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compressive strength and permeability are optimised.

Figure 8: Variation of k and fck with SF replacement levels

G. Comparison of Permeability for MK and SF

Figure 9: Comparison of Permeability for MK and SF

H. POROSITY STUDYPorosity test was carried on HPC with different mineral

admixtures (Metakaolin and Silica Fume). The specimens weretested and their porosity results are shown in Table 6. The 100 x100 x 100 mm cubes were cured by using ACT and were dried byusing oven. I. Correlation between Permeability and Porosity

k = AeBn

Where, ’k’ is the permeability (150 mm cubes) and ’n’ is theporosity (100 mm cubes) of the concrete respectively. A and B are

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the coefficients that can be obtained from the regression analysis.

J. Permeability vs. Porosity study for MK replacementsFrom fig 10, it was observed that there was a considerably

high relationship between permeability and porosity of theconcrete so that regression analysis provided correlation coefficient(R2) of 0.735.

Figure 10: k vs. n for MK replacement levels K. Permeability vs.Porosity study for SF replacements

From fig 11, it was observed that there was a considerablyhigh relationship between permeability and porosity of theconcrete so that regression analysis provided correlation coefficient(R2) of 0.732.

Figure 11: k vs. n for SF replacement levels L. Comparison ofPermeability vs. porosity for MK and SF

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Figure 12: k vs. n for MK and SF

6 SUMMARY AND CONCLUSION

A. SUMMARY

The main aim of the present investigation was to study thecompressive strength, permeability and porosity properties ofHPC. Relation between permeability vs. compressive strength,permeability vs. porosity and compressive strength results basedon NWC and ACT were discussed.

B. CONCLUSION

Based on the experimental investigations carried out, thefollowing conclusions are drawn

1. Strength parameters

• Metakaolin is giving more compressive strength thancompared to Silica Fume when the specimens are curedby Normal Water Curing.

• Silica Fume is giving more compressive strength thancompared to Metakaolin when the specimens are curedby Accelerated Curing (% achievement of compressivestrength by using ACT is 72% to 87%).

• Metakaolin at 10% replacement level shows maximumcompressive strength (93.88MPa), but whereas, SilicaFume at 15% replacement level shows maximumcompressive strength (84.66MPa).

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2. Permeability

• Silica Fume with 15% replacement level shows lowpermeability value (2.6 x 10-12 cm/sec) than comparedto other concrete mixes.

• To estimate the permeability of HPC based oncompressive strength as given in fig 3, 4, 6 and 7 aresufficiently accurate.

3. Porosity

• Silica Fume with 15% replacement level shows lowporosity value (0.22%) than compared to otherconcrete mixes.

• To estimate the permeability of HPC based on porosityas given in fig 10 and 11 are sufficiently accurate.

4. Scope for future work

• Effect of double and triple blending (combination ofdifferent mineral admixtures) on Permeability andDiffusivity of HPC has to be investigated.

References

[1] Ahmed Tafraoui (2009). “Metakaolin in the formulation ofUHPC”. Construction and Building Materials, Vol.23, pp.669-674.

[2] Adam Neville and Pierre-Claude Aitcin (1998). “Highperformance concrete- An overview”. Materials andStructures, Vol.31, pp.111-117.

[3] Bhanjaa and Sengupta (2003). “Modified water-cement ratiolaw for silica fume concretes”. Journal of Cement and ConcreteResearch, Vol.33, pp.447-450.

[4] EI-Dieb A.S and Hooton R.D. (1995). “Water-permeabilitymeasurement of high performance concrete using a high-pressure triaxial cell”. Journal of Cement and ConcreteResearch, Vol.25, No.6, pp.1199-1208.

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[5] IS 456-2000 (2000). “Plain and reinforced concrete code ofpractice”. Bureau of Indian Standards.

[6] IS 516-1959 (1959). “Methods of tests for strength of concrete”.Bureau of Indian Standards.

[7] IS 3085-1965 (1965). “Method of test for permeability ofcement mortar and concrete”. Bureau of Indian Standards.

[8] IS 9013-1978 (1978). “Method of making, curing anddetermining compressive strength of accelerated-curedconcrete test specimens”. Bureau of Indian Standards.

[9] IS 10086-1982 (1982). “Specification for moulds for use in testsof cement and concrete”. Bureau of Indian Standards.

[10] IS 15388-2003 (2003). “Silica fume specification”. Bureau ofIndian Standards.

[11] Khatib J.M. (2007). “Metakaolin concrete at a low water tobinder ratio”. Construction and Building Materials, Vol.22,pp.1691-1700.

[12] Khan M.I. and Lynsdale C.J. (2002). “Strength, permeability,and carbonation of high-performance concrete”. Journal ofCement and Concrete Research, 32 (2002), 123131.

[13] Lu Jianfu, GUAN Hui, ZHAO Weixuan and BA Hengjing(2011). “Journal of Wuhan University of Technology-Mater”.Vol.26, No.1.

[14] Miloud B. (2005). “Permeability and porosity characteristics ofsteel fiber reinforced concrete.” ASIAN JOURNAL OF CIVILENGINEERING (BUILDING AND HOUSING), Vol. 6, No.4, pp.317-330.

[15] Shetty M.S. (2005). “Concrete technology.” S.Chandpublications.

[16] Shaheer Ali K. (2010). “Strength, durability andmicrostructural studies in HPC”. M.Tech thesis, NationalInstitute of Technology, Tiruchirappalli.

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