Correct option is A
For a constant aggregate-cement ratio, if the coarse aggregate is increased at the expense of sand (fine aggregate), while maintaining the total aggregate-cement ratio constant, the total surface area of the aggregate is reduced.
This is because:
Coarse aggregates have a lower surface area compared to sand (fine aggregates).
As you replace sand with coarse aggregate, the overall surface area of the aggregate mixture decreases.
Explanation of Options:
1. Reduced:
Coarse aggregates have a smaller surface area compared to fine aggregates (sand), so increasing the proportion of coarse aggregate reduces the total surface area of the aggregates.
2. Depends on Other factors:
The surface area reduction is primarily a function of the nature of coarse and fine aggregates.
3. Remains Unchanged:
The surface area is not constant when the mix proportion of coarse and fine aggregates is changed.
4. Increased:
Increasing the coarse aggregate would reduce the surface area, not increase it.
