Project on Concrete Mix Design for various grades of Concrete

Ans :- here we have to target the strength of mix proportions f'ck = fck+ 1.65 S

here f'ck = average compressive strength for 28 days

fck = characteristics compressive strength at 28 days

S = standard deviation

from table 1 IS 10262:2009 standard deviation S = 5N/MM^2

Terefore, target strength = 35+1.65x5 = 43.25

water cement ration = maximum water cement ration = 0.40,based on experience adopt water cement ration as 0.40

0.40<0.45 hence, ok

now maximum water content for 20mm aggregate = 186ltr.

estimated water content for 100mm slump = 186 + 6/100x186 = 197 ltr. , as superplasticizer is used the water content reduce to 30% based on trial water content reduction of 29% is achieved with platicizer , arrived water content = 197x0.71 =140 ltr.

now, water cement ratio = 0.4 , cementitious material content = 140/0.4 = 350 kg/m^3

now, to proportion a mix containing fly ash the following steps are follows - a) in this persentge of fly ash needs to be decided based on project requirement and quality of material

b) it also increases in cementitious material can be warrated

cementitious material content = 350x1.10 = 385kg/m^3

water content = 140 kg/m^3

water cement ratio = 140/385=0.364

flyash@ 30% cementitious material content = 385x30%=115 kg/m^3

saving of cement while usig flyash = 350-270= 80kg/m^3

flyash being utilized = 115kg/m^3