Which factors influence the rate of strength gain in early-age concrete?

• A. Water-cement ratio, curing conditions, and temperature.
• B. Air content alone.
• C. Surface finish.
• D. Color of cement.

Answer: (A)

Early-age strength in concrete is governed by cement hydration, which needs sufficient water and a suitable temperature over time. The water-cement ratio sets how dense the paste becomes; lower ratios yield higher early strength because there is less capillary porosity for cracks to propagate, provided the mix stays adequately moist during curing. Curing conditions ensure the concrete retains moisture and stays at temperatures that support ongoing hydration; poor curing dries the concrete or keeps it too cold, slowing strength gain. Temperature controls the reaction rate—warmer curing accelerates early strength development, while extreme heat or poor temperature control can cause issues later. The remaining factors don’t directly drive early strength: air content affects durability and workability more than initial strength; surface finish and color are cosmetic and don’t influence the hydration process.