To calculate the cement and sand for 100 m 2 plastering area in 1:6 ratio and 12 mm thickness. Plastering thickness 12 mm = 12/1000 = = 100 m 2 x = m 3. (This is wet volume that means we need this much volume of cement mortar after mixing water, So for dry volume, we have to add 3035% as bulkage of sand, we are using 35% and ...