How to calculate cement, sand and aggregate quantity in concrete in Cft

There are different concretes having different ratios and strength. 

Materials of concrete may be calculated in following way for all type of concretes. We are explaining with following example. 

Calculate materials of concrete (1:2:4) having water cement Ratio of 0.45 to pour RCC slab sized 100 ft x 50 ft and 6 inch thickness. Admixture should be added @2 %. 

Calculations. 

Wet volume of concrete = Length x Width x Thickness 

=100x50x6/12= 2500 Cft. 

Dry Volume of concrete =Wet volume x Drying factor 

Note, Drying factor used for concrete is 1.54

Dry volume of concrete = 2500x1.54= 3850 Cft

Cement in bags = (Ratio of Cement x Dry Volume) /(Sum of Ratios). (Volume of one cement bag). 

1-Cement in Bags =(1x3850)/(1+2+4).(1.25)= 440 Bags

2-Sand in Cft  = (Ratio of Sand x Dry Volume) /(Sum of Ratio) 

=(2x3850)/(1+2+4)= 1100 Cft

3-Crush stone in Cft  = (Ratio of Crush x Dry Volume) /(Sum of Ratio) 

=(4x3850)/(1+2+4)= 2200 Cft

4- Water in Liters = Weight of cement in kgs x Water cement ratio= Liters

= 440 Bags x 50 kg x. 45 = 9900 Liters

5- Admixture = Weight of cement x % part of admixture 

= 440x50x2/100= 440 Liters