Which factor is not listed as influencing early-age strength?

• A. Water-cement ratio
• B. Curing conditions
• C. Thermal conductivity of the concrete
• D. Temperature

Answer: (C)

Early-age strength comes from cement hydration, which is directly influenced by water availability, how well the concrete is cured, and the temperature at which it cures. The water-cement ratio determines how much water is available for hydration and thus how much cement can gain strength early on. Curing conditions keep the surface moist and at a suitable temperature so hydration can continue rather than halt or slow. Temperature affects the rate of hydration itself—higher temperatures speed up early strength gain, while low temperatures slow it down.

Thermal conductivity describes how well heat moves through the concrete. While this property affects how heat distributes within the slab, it does not directly change the hydration chemistry or the early strength development in the same way the other factors do. So it’s not considered a direct factor influencing early-age strength.