Question

How Does the Ratio of Sand to Cement Affect the Strength of Concrete? Explain in details

Answer 1

Factors affecting the strength of concrete are,

• Water to cement ratio
• Coarse to fine aggregate ratio
• Aggregate to cement ratio
• Age of concrete
• Degree of compaction
• Temperature
• Degree of curing etc.

As per the request of question I only consider the sand to cement ratio.

• If the volume remains the same and the proportion of cement in relation to that of sand is increased the surface area of the solid will increase.
• If the surface area of the solids has increased, the water demand will stay the same for the constant workability.
• Assuming an increase in cement content for no increase in water demand, the water cement ratio will decrease.
• If the water cement ratio reduces, the strength of the concrete will increase.

The influence of cement content on workability and strength is an important one to remember and can be summarized as follows:

1. For a given workability an increase in the proportion of cement in a mix has little effect on the water demand and results in a reduction in the water/cement ratio.
2. The reduction in water/cement ratio leads to an increase in strength of concrete.
3. Therefore, for a given workability an increase in the cement content results in an increase in strength of concrete.