Concrete containing:

🌡️ Aggregate Type and Thermal Expansion

The coefficient of thermal expansion of concrete depends mainly on the aggregate type, since aggregate makes up 70–80% of the volume. All three statements are correct:

A: Siliceous aggregates (quartz-based sands and gravels) have the highest coefficient of thermal expansion, around 11–12 × 10^–6/°C.

B: Igneous aggregates (granite, basalt) have an intermediate coefficient, typically 8–10 × 10^–6/°C.

C: Limestone aggregates have the lowest coefficient, around 6–8 × 10^–6/°C — which is why they are preferred in pavements and mass concrete where thermal movement matters.

Key takeaway

Siliceous > igneous > limestone for thermal expansion. Limestone concrete is the most thermally stable.