Sai kiran Reddy1, Graduate student – Civil Engineering Department,saveetha school of engineering ,Saveetha university, Chennai, India, [email protected] krishna2, Graduate student – Civil Engineering Department,saveetha school of engineering ,Saveetha university, Chennai, India, [email protected] dave3, Asst Professor – Civil Engineering Department, SaveethaSchool of Engineering, Saveetha University, Chennai, India, [email protected]
com ABSTRACT:Theuse of silica fume had major impact on construction industry. This study is anexperiment on the nature of silica fume and its influences on the properties offresh concrete. The partially replacement of cement by silica fume the strengthparameters of concrete have been studied. First, the strength parameters ofconcrete without any partial replacement was studied.
Then, we replaced thecement with silica fume of different ratios (10%,15%,20%) and results werecompared with normal concrete .After 10% replacement it is observed that thestrength is gradually decreased .KEY WORDS: silicafume , Compressive strength etc1. INTRODUCTION:1.1. MATERIALS:CEMENT :ordinary Portland cement (opc) of M53 grade is used in casting AGGREGATE: coarse aggregate which are sieved at a size of 20mm are used WATER: Tap water which are suitable for constructionis used.
SILICAMESH 800:It is used for replacement of cementby 10%,15%,20% water cementratio is 0.451.2.1.METHODOLOGY FIGURE NO :01 2.REVIEW OF LITERATURE:Abdulaziz A. Bubshaitet.
al :Investigatedthat the advantages of using micro silica can be considerable as it reducesthermal cracking caused by the heat of cement hydration and can improvedurability to attack by sulphate and acidic water, giving increase inperformance of concrete. The optimum replacement of cement by silica fume gavehigh durability, permeability, high compressive strengthFaseyemi Victor Ajileyeconcludedcement replacement up to 10% with silica fume leads to increase in compressivestrength for M30 grade of concrete. From 15% there is a decrease in compressivestrength for 3, 7, 14 and 28 days curing period. It was observed that thecompressive strength of M30 grade of concrete was increased from 16.15% to29.24% and decrease from 23.
98% to 20.22% maximum replacement level of silicafume was 10% for M30 grade of concrete.N.K. Amudhavalli andjeena Mathew : Thisresearch concluded that with increase in fineness of cement consistencyincreases. Silica fume is having greater fineness than cement and greatersurface area so the consistency increases greatly, when silica fume percentageincreases. The normal consistency increases about 40% when silica fumepercentage increases.
The normal consistency increases about 40% when silicafume percentage increases from 0% to 20%. The 7 and 28 days compressivestrength and flexural strength was obtained in the range of 10% to 15% silicafume replacement level. Increase in split tensile strength beyond 10% silicafume replacement was almost unsatisfactory whereas increase in flexural tensilestrength occurred up to 15% replacement. Silica fume to have a moresatisfactory effect on the flexural strength as compared to tensile strength.When the mix was compared to another mix the weight loss and compressivestrength percentage was found to be reduced by 2.
23 and 7.69 respectively whencement was replaced by 10% of silica fume.Des King:Investigatedthe impact of silica fume in concrete under various properties such asworkability, permeability, durability, bleeding, heat of hydration, sensitivityto curing, acid resistance, tensile strength, flexural strength etc. Heconcluded that the 28th days strength of concrete with silica fume gives ahigher strength of compressive strength as compared to any other material suchas fly ash , GGBS etc. With addition of silica fume early high compressivestrength can be achieved, further a very high strength can be achieved after 28days with proper concrete mix design method. Vikas Srivastava et. Al:Workedout the workability of concrete on optimum replacement of silica fume bycement.
Their research concluded that the workability reduces with the additionof silica fume. However in some cases improved workability was observed. Withthe addition and variation of replacement levels of silica fume the compressivestrength significantly increased by (6-57%). There was no change observed inthe tensile and flexural strength of the concrete as compared to theconventional concrete.Debabrata Pradhan andD. Dutta :Investigatedthe effects of silica fume on conventional concrete, concluded the optimumcompressive strength was obtained at 20% cement replacement by silica fume at24 hours, 7days and 28 days. Higher compressive strength resembles that theconcrete incorporated with silica fume was high strength concrete.3.
EXPERIMENTALPROCEDURE: PREPARATIONOF CUBE SPECIMENS:Theproportion and material for making these test specimens are from the sameconcrete used in the field.SPECIMEN : 3cubes of 15 cm*15cm*15cm size we need to applyoil or grease for the cube and tighten the screws of cube as shown in figure 02 FIGURE NO :023.1.
MIXING: After the sample has been mixed, immediatelyfill the cube moulds and compact the concrete, either by hand or by vibration.Any air trapped in the concrete will reduce the strength of the cube.3.2HAND MIXING:Mixthe cement on a water tight none-absorbent platform until the mixture isthoroughly blended and is of uniform colour. FIGURE NO :03Addthe coarse aggregate and mix with cement and fine aggregate until the coarseaggregate is uniformly distributed throughout the batch.Addwater and mix it until the concrete appears to be homogeneous and of thedesired consistency.3.
3. CASTING:Thecubes must be fully compacted moulds should be filled in three approximatelyequal layers (50 mm deep). A compacting bar is provided for compacting theconcrete. It is a 380 mm long steel bar, weighs 1.8 kg and has a 25 mm squareend for ramming. During the compaction of each layer with the compacting bar,the strokes should be distributed in a uniform manner over the surface of theconcrete and each layer should be compacted to its full depth. During thecompaction of the first layer, the compacting bar should not forcibly strikethe bottom of the mould. For subsequent layers, the compacting bar should passinto the layer immediately below.
The minimum number of strokes per layerrequired to produce full compaction will depend upon the workability of theconcrete, but at least 35 strokes will be necessary except in the case of veryhigh workability concrete. After the top layer has been compacted, a trowelshould be used to finish off the surface level with the top of the mould, andthe outside of the mould should be wiped clean.3.4. DEMOULDING: Testcubes should be demoulded between 16 and 24 hours after they have been made. Ifafter this period of time the concrete has not achieved sufficient strength toenable demoulding without damaging the cube then the demoulding should bedelayed for a further 24 hours. When removing the concrete cube from the mould,take the mould apart completely.
Take care not to damage the cube because, ifany cracking is caused, the compressive strength may be reduced.Afterdemoulding, each cube should be marked with a legible identification on the topor bottom using a waterproof crayon or ink. The mould must be thoroughlycleaned after demoulding the cube. Ensure that grease or dirt does not collectbetween the faces of the flanges, otherwise the two halves will not fittogether properly and there will be leakage through the joint and anirregularly shaped cube may result.
3.5. CURING:Cubesmust be cured before they are tested. Unless required for test at 24 hours, thecube should be placed immediately after demoulding in the curing tank or mistroom. The curing temperature of the water in the curing tank should bemaintained at 27-30°C.
If curing is in a mist room, the relative humidity shouldbe maintained at no less than 95%. Curing should be continued as long aspossible up to the time of testing.Inorder to provide adequate circulation of water, adequate space should beprovided between the cubes, and between the cubes and the side of the curingtank. If curing is in a mist room, there should be sufficient space betweencubes to ensure that all surfaces of the cubes are moist at all times4.
RESULTSAND DISCUSSION:The tests conducted on concretemix are as follows4.1.NORMALCONSISTENCY TEST: Time Penetration Reading 0 0 5 0 10 0 15 0 20 0 25 3 30 6 4.2.INITIAL SETTING TIMETEST Quantity Of Cement Taken (Grams) Percentage Of Water Amount Of Water (Ml) Penetration Reading 400 25% 100 31 400 30% 120 23 400 35% 140 15 400 36% 152 7 4.3. FINAL SETTING TIMETEST NAME OF THE TEST RESULT Final Setting Time 600minutes(10 Hours) 4.
4.COMPRESSIVESTRENGTHTEST OF CONVENTIONAL PERVIOUS CONCRETE (7,14,28 DAYS) specimen compressive strength(7days) compressive strength(14days) compressive strength(28days) CUBE 1 17 23 27.02 CUBE 2 15.8 22 24.04 CUBE 3 17.2 22.5 25.33 4.
5. COMPRESSIVE STRENGTH TEST OF 10% SILICAMESH800 OF (7,14,28 DAYS): specimen compressive strength(7days) compressive strength(14days) compressive strength(28days) CUBE 1 8.40 36 42.55 CUBE 2 8.4 37.24 43.24 CUBE 3 8.
4 37.86 44.66 4.6. COMPRESSIVE STRENGTHTEST OF 15% SILICAMESH800 CONCRETE OF (7,14,28 DAYS) specimen compressive strength(7days) compressive strength(14days) compressive strength(28days) CUBE 1 27.46 30.
04 33.24 CUBE 2 22.57 29.
46 34.22 CUBE 3 24.04 32.44 36.08 4.7.
COMPRESSIVE STRENGTH TEST OF 20% SILICAMESH800 CONCRETE OF (7,14,28 DAYS) specimen compressive strength(7days) compressive strength(14days) compressive strength(28days) CUBE 1 26.53 25.2 31.28 CUBE 2 22.44 26.04 30.04 CUBE 3 22.02 27.
46 29.77 4.8.COMPARISION OF COMPRESSIVE STRENGTHFOR DIFFERENT PERCENTAGES OF SILICAMESH800 : Figure no:4 5. CONCLUSION· That withincrease in workability the compressive strength decreases. · The optimumreplacement of cement with silica fume 10% to 15% leads to increase incompressive strength whereas the percentage replacement of 20% leads todecrease in compressive strength. · Variationof w/c ratio has an impact on compressive strength of concrete.
With theincrease in w/c ratio the compressive strength decreases and vice versa. · Addition ofsilica fume in proper proportion improves durability attack by acidic watersand improving concrete conditions. · Silica fumehaving high fineness leads to high normal consistency. · Silica fumegives a higher strength of compressive strength as compared to any othermaterial such as fly ash, GGBS. 6.
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