Project on Concrete Mix Design for various grades of Concrete
1) Grade designation - M35, type of cement -opc 53grade, Type of admixture - fly ash, maximum nominal size of aggregate - 20mm, minimum cement content as per Is code 456 2000- 340kg, maximum cement content - 450kg, partial replacement of cement by fly ash - 30%, maximum w/c -0.45, slump - 100mma, chemical admixture - super plasticizer. Specific gravity of cement - 3.15, specific gravity of fly ash - 2.90, chemical admixture @0.6%, specific gravity of coarse aggregate - 2.74, specific gravity of fine aggregate - 2.74, specific gravity of chemical admixture - 1.12, water absorption of coarse aggregate - 0.5%, water absorption of fine aggregate - 1%, seive analysis of fine aggregate - zone II. target mean strength = fck+1.65S. according to IS code 10262-table 1, S=5, So target mean strength = 35+1.65x5=43.25N/sqmm. Selection water cement ratio:- maximum w/c = 0.45, adopted w/c =0.45, Selection of water content:- maximum water content = 186liters as per IS code 10262 of table 2. The water content for above is for 25mm to 50mm. Therefore to get desired slump of 100mm, the water content has to be increased. As per IS code for every addition 25mm increase in slump 3% of water content to be increased for every 25mm. So water content for slump of 100mm = 186+(2x3/100)x186=197.16liters. As we are using super plastisizer the water content can reduced by 20%. So the water content = 197-0.2x197=157.6liters say 158liters. Calculation of cement and fly ash:- adopted w/c =0.45, total cementatious content = water content/water cement ratio= 158/0.45=351.11kg. Since we are using flyash, the amount cementious content should be increased to get better performence and strength. The percentage of flyash depends upon reasearch and experience. Here we are increasing cementitious content by 10%. So the final cementitous content =1.10x351.11=386.22kg As per IS code 456 of table the cement content is 340kg but in our case the cementateos content is 386.22kg which is higher so its ok. Flyash content is 30% of cementateous content. so flyash=386.22x0.3=115.87kg. cement content=cementetious content-flyash=386.22-115.87=270.35kg. calculation of suoerplastisizer is 0.6% of cementiteous content= 386.22x0.06=23.17kg/cum. coarse fine aggregate:- The coarse aggregate as per IS code 10262 table 3 for zone II for 20mm aggreagte is 0.62 for w/c of 0.5, but in our case the w/c is 0.45 so for every 0.05 decrease in w/c we have increase the volume 0.01cum so the total coarse and fine aggregate volume= 0.62+0.01=0.63cum.The fine aggreagte= 1-0.63= 0.37cum. Mix calculation of m-35 grade of concrete:- A)volume of concrete=1cum. B)total volume cement =cement/(SG of cementx1000)= 270.35/(3.15x1000)=0.086cum. C)volume fly ash = flyash/(SG of flyashx1000)=115.87/(2.9x1000)=0.053cum.D)volume of water= water/(SG of waterx1000)=157.6/(1x1000)=0.158cum. E)Volume superplastisizer= weight of super plastisizer/(SG of super plastizerx1000)=23.17/(1.12x1000)=0.021cum. F)Total aggregate requirement=A-(B+C+D+E)=1-(0.086+0.053+0.158+0.021)=0.682cum. G) coarse aggregate = Fxcoarse aggregatexSGx1000=0.682x0.63x2.74x1000=1177.3kg. zfine aggregate= Fxfine aggregate volumexSG of fine aggregatex1000= 0.682x0.37x2.74x1000=691.41kg
2) Grade designation - M50, type of cement - opc 43 grade, fine aggregate - zone Ii, admixture - superplastisizer. Specific gravity of cement- 3.12, specific gravity of fine aggregate- 2.56, specific gravity of coarse aggregate - 2.74. minimum cerment content - 360kg/cum, maximum w/c-0.35, workability (slump) - 50-75mm, exposure - extreme for reinforce cement concrete, method of concrete placing - pump. maximum water content - 450kg/cum. procedure:-1) Target mean strength = fck+1.65S. according to table 1 of IS code 10262-2009 standard deviation S=5N/sqmm. Therefore target mean strength= 50+1.65x5=58.25N/sqmm. 2)Selection of W/C as per table 5 IS 456-2000 w/c =0.35. 3) selection of water content:- from table 2 of IS 456-2000 maximum water content=186liters for 25 to 50mm slump. Estimated water content for 100mm slump=186+6/100x(186)=197liters.Note :- if super plasstisizer is used water content can be reduced upto 20% and above. Based on trials witth super plastisizer water content reduction is acheived upto 27%. Hence the arrived water content=197-(27/100x197)=143liters. 4) calculation of cement content:- w/c=0.35. cement content=143/0.35=410kg/xcum. From table 5 ofiS 456-2000 the cement content for extreme exposure is 360kg/cum which greater, hence o.k. 5) Proportion coarse and fine aggregate content:- table 3 of 10262 volume of coarse aggregate corrosponding to 20mm size aggragate and fine aggregate (zone II) for w/c of 0.5 = 0.62. But in our the w/c is 0.35. hence the volume of coarse aggreagtes is required to be increased to decrease volume of fine aggregates content. As w/c is lower by 0.1, the proportion of coarse aggregates is to be increased by 0.02. So the corrected volume of coarse aggregates = 0.62+(0.1/0.05)x0.01=0.64cum.6) Mix calculations:- a) volume of concrete =1cum, b) volume cement= (mass of cement/ its SG)x1/1000=(410/3.12)x1/1000=0.131cum. b) Volume of water = (mass of water/its G)x(1/1000)=(143/1)x1/1000=0.143cum. d) zolume of super plastisizer=(mass of superplastisizer/its Sg)x1/1000=(8.2/1.145)x1/1000=0.007cum. e) volume of all aggregate=a-(b+c+d)=1-(0.131+0.143+0.007)=0.719cum. f) mass of coarse aggregates=volume of all aggregatesxvolume coarse aggreagtesxSG of coarse aggregatesx1000=0.719x0.585x2.74x1000=1152.48kg/cum. g) mass of fine aggregates = volume of alla agggreagatesxvolume of fine aggregatesxSG of fine aggregatesx1000=0.719x0.415x2.56x1000=763.86kg/cum.
Cement = 410kg/cum. water=143kg/cum. superplastisizer=7kg/cum. fine aggregates=763.86kg/cum. coarse aggregates=1152.48kg/cum. w/c=0.
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