Formula for calculating cement consumption for M20 grade nominal mix concrete?

M20 = 1:1.5:3

Volume = 1+1.5+3=(5.5 parts )

Total volume ingredients for using 2omm jelly =1.57

Volume of broken stone Require = (3/5.5) x 1.57 = .856 Cum

Volume of sand Require = (1.5/5.5 ) x 1.57 = .471 Cum

Volume of cement = (1/5.5) x 1.57 = .285 Cum

= .285 x1440 = 411 kg

= (8.22 bag )

For 1Cum of M20 ( 1:1.5:3 )

20mm jelly = 0.856 cu.m

sand = 0.472 cu.m

cement = 8.22 bag