Spalling is the breaking away of larger fragments from a concrete surface, originating from deeper within the slab, often due to rebar corrosion, moisture intrusion, freeze-thaw pressure, or poorly formed joints.
In depth
Unlike surface flaking, spalling starts below the surface. Steel reinforcement that rusts expands and pushes off the concrete cover, water that freezes inside the slab forces fragments loose, and stress at bad joints breaks pieces away. The result is visible pitting and chunks missing from the surface, which can expose aggregate or rebar.
Spalling is a concrete-material issue rather than a soil-support issue, so it is distinct from settlement. That said, the moisture and freeze-thaw conditions that drive spalling also drive the soil movement that sinks slabs, so the two often appear together.
How Acme applies it. Spalling reflects damage within the concrete itself; where a slab is also sinking or unsupported, Acme’s polyurethane raising and void filling address the underlying soil and stability problems.
Related terms: Scaling, Concrete Cracking, Freeze-Thaw Cycle, Curling
Frequently asked questions
What is the difference between spalling and scaling?
Spalling breaks away larger fragments from deeper in the slab, often from rebar corrosion or internal pressure. Scaling is shallower, affecting only the top surface layer, which flakes or peels.
Does concrete raising fix spalling?
Concrete raising corrects sinking and voids, not surface spalling. Spalled concrete typically needs surface repair or patching, though addressing the moisture behind it helps prevent recurrence.