Sulfate resistance of self compacting concrete incorporating mineral admixtures

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 10 Issue: 01 | Jan 2023 www.irjet.net p-ISSN: 2395-0072

Sulfate resistance of self compacting concrete incorporating mineral admixtures

1 , S.Bhavanishankar2

1Lecturer, Government Polytechnic, Ramanagara, Karnataka

2 Associate Professor and guide, Department .of Civil Engineering, U.V.C.E., Bangalore University, India ***

Abstract - – A self-compacting concrete (SCC) is the one that can be placed in the form and can go through obstructions by its own weight and without the need of vibration. SCC provides better quality especially in the members having reinforcement congestion or decreasing thepermeabilityandimprovingdurabilityofconcrete.

Chemical attacks on concretestructures causes deterioration of structure and its durability is affected. Sulphate attack is one of the most common aggressive actionsleadingtothedeteriorationofconcrete.

The scope of the work is to develop suitable mixes containing the mineral admixtures to satisfy the requirements of SCC using local aggregates and to determine the strength and durability of such concrete exposedtosulphateattack.

The study showed remarkable improvements in properties of self-compacting concrete by incorporation of mineral admixtures at various proportions and improved resistance against sulfate attack. Conclusions are drawn basedontheexperimentalresults.

Key Words: Self compacting concrete, mineral admixtures, sulphate attack, partial replacement by mineraladmixtures.

1. INTRODUCTION

Self Compacting Concrete was first developed in Japan in 1988inordertoachievemoredurableconcretestructures by improving the quality achieved in the construction processandtheplacedmaterial.

Self-compactability is largely affected by the characteristicsofmaterialsandthemixproportions.

As per the EFNARC guidelines of mix design the main difference between the normal concrete and the self compacting concrete is the incorporation of mineral admixtures. Partial replacement of cement with mineral admixtures particularly industrial waste products such as fly ash, blast furnace slag and silica fume improves propertiesofconcretesignificantlyandfavorably.

In this study, Self compacting concrete Specimens are designed incorporating mineral admixtures at different

combinations and tested for compressive strength and splittingtensilestrengthandthevariationsintheirweight and strength are noted after accelerated attack of sodium sulfatesolutionwith15%concentration.

2. Experimental Program

Materials:

Self compacting concrete was made with the cement, manufactured sand, coarse aggregates, water and the mineraladmixtures.

Cement: Ordinary Portland cement, 43 grade confirming toIS8112:2013.

Fine aggregate: Locally available manufactured sand confinedtogradingzoneIIofIS:383-1970.

Coarse aggregates: Locally available crushed granite stones confirming to graded aggregates of sizes 16mm downand12.5mmdown.

Mineral admixtures: ground granulated furnace slag from Jindalsteelplant,ClassFflyash,andsilicafumewereused asmineraladmixtures.

Chemical admixtures: Glenium B233 is used as super plasticizer.

Mix design:

Fourtypesofmixproportionswerecarriedout

Mix1

Controlmix

Mix2

Mix3

Mix4

Self compacting concrete without any replacementtocement

Replacement of cement with Silica fume10%,GGBS10%,Flyash30%

Replacement of cement with Silica fume10%,GGBS20%,Flyash20%

Replacement of cement with Silica fume10%,GGBS30%,Flyash10%

Table1showingdifferentmixes.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 10 Issue: 01 | Jan 2023 www.irjet.net p-ISSN: 2395-0072

MixdesignwaspreparedbyOkumaramethod. Thetable2 belowshowsthecompositionofSCCmixes.

Mix OPC Kg/m3

kg/m3

Table2showingcompositionofSCCmixes

Test methods:

Fresh state Properties: Slumpflow test,T5o timefunnel time,Lboxtest,Uboxtest,Jringtestswereperformedfor determiningtheworkability propertiesofselfcompacting concretetomeettheEFNARCstandards.

Hardened tests: Thehardenedpropertiesinvestigatedin this study are compressive strength tests and splitting tensile strength test. Compressive strength test was performed on (15x15x15) cm cubes where as tensile strength was assessed indirectly by the splitting test on cylinders.

Sulfate attack:

The sulfate attack test was performed by immersing the cubes and cylinder specimens in 15% sodium sulfate solutionfor28 days after curing of28 days in water.This type represents an accelerated testing procedure where the higher concentration than that exists in the field is used for accelerated testing. The resistance of concrete is evaluatedbynotingthechangeinstrengthandweight.

3. Test Results

Fresh state Properties:

Table 3 shows the results of fresh properties of Self compactingconcretemixes.

Intermsofslumpflow,allSCCmixesexhibitedsatisfactory slump flows in the range of 650-690 which is a sign of gooddeformability.

All the fresh concrete properties were in good agreement withtherangeofvaluesgivenbyEFNARC.

Hardened state properties:

The strength parameters were studied through compressivestrengthandsplittensilestrength.

Among the mixes, the strength in blended combination of OPC replacement with 30% GGBS, 10% FA, 10% SF is foundhigherthanotherblendedcombinationswhereasit is lesser for the control mix. The early age strength is lesserormarginallyhigher whencompared tothecontrol mix whereas strength exceeded at later stages for the blendedmixes

0 5 10 15 20 25 30 35 40 45 compressive strength in N/mm2

Table3showingfreshpropertiesofdifferentmixes.

Mix1 Mix2 Mix3 Mix4

Avg compressive strength 7 days N/mm2 21.15 20.12 20.5 22.1

Avg compressive strength 28 days N/mm2 30.12 31 31.67 35.55

Avg compressive strength 56 days N/mm2 32.1 34.2 35.5 39.89

Chart1showingcompressivestrengthsatvariousages.

Chart showing Split tensile strength

Chart showing compressive strength Mix1 Mix2 Mix3 Mix4

Average split tensile strength at 7 days of water curing in N/mm2 2.31 2.16 2.32 2.43

Average split tensile strength at 28 days of water curing in N/mm2 3.08 3.11 3.45 3.6

Chart2showingSplittensilestrengthsatvariousages.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 10 Issue: 01 | Jan 2023 www.irjet.net p-ISSN: 2395-0072

Sulfate attack:

Surface deterioration was not clearly identifiable on the concrete specimens immersed in 15% sodium sulphate solution. No change in length was observed. Light whitish depositswereseenonthesurfaceofthespecimens.

When subjected to continuous exposure to sulfate all the specimens showed increase in weight. The gain in weight for Mix 1 were in the range of 0.3 and 0.38% for cubes andcylinders.Similarlythegaininweightformix2,3and 4 were 0.18 and 0.26%, 0.25 and 0.23%,0.12 and 0.19 % respectivelyforcubesandcylinders.

Table 4 gives the percentage weight gain for the 4 mixes afterimmersingin15%Na2SO4 solutionfor28days.

Chart3showingchangeinweightafter28daysof immersioninsodiumsulfatesolution

Chart 4 and 5 gives the percentage gain in compressive andsplittingtensilestrengthgain afterimmersingin15% Na2SO4 solution for 28 days after initial water curing for 28days

Chart4Percentagegainincompressivestrengthafter28 dayssulfateexposure

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 split tensile strength in N/mm2

after 28 days immersion in Na2SO4 media 3.15 3.31 3.71 4.02

Chart5Percentagegaininsplittensilestrengthafter28 dayssulfateexposure

Allconcretespecimensshowedincreaseinstrengthwhen compared to 28 days water cured specimens. The percentage gain in compressive strength were 4.91, 7.19, 9.88 and 10.27% respectively for mix1, mix2, mix3 and mix4.Thepercentagegaininsplittingtensilestrengthwas 2.27, 6.43, 7.53 and 11.66 % respectively for mix1, mix2, mix3andmix4.

When compared to water cured specimens of same age there was decrease in both compressive and split tensile strengthsasshowninthechartbelow.

Comparison of water cured and sulphate exposure specimens

0 5 10 15 20 25 30 35 40 45 compressive strength in N/mm2

Chart showing gain in split tensile strength Mix 1 Mix 2 Mix 3 Mix 4

Compressive strength after 56 days water curing 32.1 34.2 35.5 39.89 compressive strength after 28 days water curing and 28 days immersion in sodium sulfate 31.6 33.23 34.8 39.2

Chart5showingcomparisonofcompressivestrengthsof specimensofsameages.

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 10 Issue: 01 | Jan 2023 www.irjet.net p-ISSN: 2395-0072

products such as ettrignite and gypsum which possess more volume and densification of microstructure.



From the experiment it is found that, all SCC specimens showed increase in compressive, split tensile strength when subjected to sulphate exposurefor28daysafterinitialwatercuringfor 28 days. The increase in strength may be attributedtotwotypesofreactions:



split strength after 28 days water curing and 28 days immersion in sodium sulfate

Chart6showingcomparisonofsplittingtensilestrengthof specimensofthesameages.

4. Conclusions

The following conclusions were drawn from the investigations

 All the mix proportions developed satisfied the requirements of self compacting concrete specifiedbyEFNARC.





From the experiments it is noticed that the blended mixes with mineral admixtures of silica fume,GGBSandflyashshowedhigherworkability comparedtomixwith100%cement.

It was observed that 28 days strength of blended mixes was higher when compared to control mix. The enhancement of strength may be due to increased pozzolonic reaction and synergetic effectofvariousadmixturesused.

The continuous hydration of cement components to form more hydration products, in addition to the reaction mineral admixtures with the free lime to form more C-S-H leading to increased strength.





Reaction of sulphate ions with hydrated cement components to form gypsum and etrignite.

Loss in strength was observed when 56 days water cured specimens are compared with specimens of 28 days water cures and 28 days sulphateexposedspecimens.



Among the blended concrete mixes, Mix 4, OPC replacement with 30% GGBS,10% FA,10% SF showed higher strength when compared to combinations where as it was lesser for the controlmix.

SulphateattackonSCCSpecimens:



Surface deterioration was not clearly identifiable by visual examination of the concrete specimens immersedin15%sodiumsulphatesolution.Light whitish deposits were seen on the surface of the specimens.

 It was observed that the all the specimens had shown marginal increase in mass when exposed to sulphate for 28 days after initial curing of 28 days. This may be due to deposition of reaction



The mix4 with OPC replacement by 10% Silica fume, 20%Flyash and 30%GGBS showed higher strength gain after 28 days of exposure to sulphate. 

Mixes with Higher percentages of GGBS showed bettersulphateresistance.

BIOGRAPHIES

Manjunath A.N is working as lecturer in Civil Engineering at Government Polytechnic, Ramanagara.

S.Bhavanishankar is Associate ProfessorintheDepartmentofCivil Engineering,U.V.C.E.,Bangalore.His research interests include Structural Engineering, Self compacting concrete, nano concretes, Rehabilitation and retrofittingofstructures.