Which term describes the deterioration that occurs when concrete pockets crumble due to heat exposure?

• A. Scaling
• B. Efflorescence
• C. Erosion
• D. Spalling

Answer: (D)

When concrete shows surface pieces popping away or crumbling in localized pockets after heat exposure, the term that fits is spalling. Heat causes the concrete surface to expand, and trapped moisture inside the pores can turn to steam, building pressure that makes these surface layers crack and detach. That action creates chunks or pockets that spall off, leaving rough, irregular areas.

This differs from scaling, which is a thinner, flaky layer that tends to come off more casually and is often linked to freeze–thaw cycles or improper finishing rather than a heat-induced internal pressure. Efflorescence isn’t about mechanical breakage at all—it’s the white salt deposits that migrate to the surface with moisture. Erosion describes material loss from weathering or flowing water, not the heat-driven cracking and breaking of the surface. So the mechanical, chunking detachment caused by heat is best described as spalling.