Pick up the correct statement from the following:

Statements on Concrete Strength Gain

All three statements are correct:

A: Concrete gains strength through the hydration of cement — the exothermic reaction of cement compounds with water to form calcium silicate hydrate (C-S-H) gel, which is the primary binding phase.

B: Concrete cured at temperatures below 23°C still gains strength over 28 days; hydration simply proceeds more slowly at lower temperatures. It does not stop until near 0°C.

C: At the freezing point (0°C), water in the mix freezes and hydration effectively stops because liquid water is no longer available for reaction. The concrete does not set under frozen conditions.

Key takeaway

Strength comes from hydration. Cold slows it; freezing stops it. Below 23°C is fine for 28-day gain; at 0°C concrete stalls.