85 Describe the effects of watercement ratio on the compress

8.5 Describe the effects of water/cement ratio on the compressive strength of concrete. Relate these effects to the structure of the HCP and its voids with varying W/C ratios. 8.6 Explain effects of age since mixing on the strength of concrete, and include consideration for the influence of the type of drying conditions.

Solution

The compressive strength of concrete is inversely related to the water cement ratio. Higher the w/c ratio, lower the compressive strength. Lower the w/c ration, higher the compressive strength. But at lower w/c ratio, plasticizers must to used for the workability purpose.

When sufficient water is mixed to cement the formed paste is called hydrated cement paste (HCP). The cement paste ensures some concrete properties like strength, volume change, permeability etc.

The voids in the HCP are,

1. Capillary voids

2. Air voids

3. Interlayer spaces

As the water content increases in the HCP, the voids in the HCP decreases thus refucing the compressive strength of the concrete.