Plain Cement Concrete (P.C.C)

1. The materials required for preparation of cement concrete are cement, sand (i.e. fine aggregates) and ballast (i.e. coarse aggregates) which are to be mixed in the predetermined proportion.
2. The voids in the coarse aggregates are filled by fine aggregates and that in the fine aggregates are filled with by cement paste (i.e. cement and water).
3. Thus the wet volume of the cement concrete (i.e. when water is added to the dry cement concrete mix) will always be less than its corresponding dry volume (i.e. sum of total volume of each ingredient added together).
4. It has been observed that in order to prepare 1 cum. of wet cement concrete, the corresponding dry volume required is about 1.52 cum.
5. Knowing the mix of the cement concrete (i.e. 1:4:8 or 1:3:6 or 1:2:4 etc.) the ingredient materials required can be determined as follows:

To determine the materials required for 1 cum. of (wet) concrete of 1:4:8 proportion, the dry volume of concrete required will be 1.52 cum. (which shrinks to 1 cum. after adding of water to it)

As 1 cum. of cement is equivalent to 30 bags of cement (each bag weighing 50 kg)

The quantity of cement required = 0.117 x 30 = 3.51 bags = 3.50 bags.

The following table gives the quantities of materials required for cement concrete of various proportion (i.e. mix) by volume.

• Computations of Quantities of Materials Required for Various Items of Works