FULLER'S FORMULA
Let:
C = number of bags of cement per cubic meter of concrete work (bag/m3)
S = volume of sand per cubic meter of concrete work (m3 of sand /m3)
G = volume of gravel per cubic meter of concrete work (m3 of gravel /m3)
c,s,g = cement-sand-gravel ratio (relative amounts of solids by volume in a mixture)
C = 55 / (c+s+g)
S = 0.028*C*s
G = 0.028*C*g
The classes of concrete mixture depends on the cement-sand-gravel ratio (c:s:g).
Class A (1:2:4) = for beams, slabs, columns, all members subjected to bending
Class B (1:2.5:5) = member not reinforced for bending stress
Class C (1:3:6) = for footing (not under water)
Note: We use here 94 lbs Portland Cement per cubic meter of concrete
Example 1:
Determine the number of bags of cement, sand, and gravel of a proposed concrete pavement whose width and length are 100 m x 200 m. The thickness is 100 cm.
Given: Width = 100 m Length = 200 m Thickness = 0.1 m
Reqd: number of bags of cement, sand, and gravel
Solution:
Volume of concrete = 100 * 200 * 0.1 = 2000 m3
Pavement = Class A (1:2:4)
C = 55 / (c+s+g) = [ 55 / (1+2+4) ] * 2000 = 15,680 bags
S = 0.028*C*s = {0.028* [ 55 / (1+2+4) ] * 2 } * 2000 = 800 m3 of sand
G = 0.028*C*g = {0.028* [ 55 / (1+2+4) ] * 4 } * 2000 = 1760 m3 of sand
