Rapid hardening cement attains early strength due to A. Larger proportion of lime grounded finer than normal cement B. Lesser proportion of lime grounded coarser than normal cement C. Lesser proportion of lime grounded finer than normal cement D. Excess percentage of gypsum

The correct answer is: D. Excess percentage of gypsum.

Rapid hardening cement is a type of cement that gains strength more quickly than ordinary Portland cement. It is made by adding an excess of gypsum to ordinary Portland cement. The gypsum slows down the hydration of the cement, which allows the cement to gain strength more quickly.

The other options are incorrect because:

• A. Larger proportion of lime grounded finer than normal cement. This would result in a cement that is slower to harden, not faster.
• B. Lesser proportion of lime grounded coarser than normal cement. This would also result in a cement that is slower to harden.
• C. Lesser proportion of lime grounded finer than normal cement. This would result in a cement that is weaker, not stronger.

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