👉Types of cracks in concrete

💫1. Plastic shrinkage cracks

⏺Appearance: Narrow, shallow, usually parallel surface cracks that appear within hours of placing concrete.

⏺Cause: Rapid moisture loss from fresh concrete (wind, heat, low humidity).

⏺Severity/repair: Mostly cosmetic if shallow — broom finish, lite patching, or surface sealant. Prevent with curing and wind breaks.

💫2. Drying (shrinkage) cracks

⏺Appearance: Random fine to moderate cracks across the slab; often develop within days/weeks.

⏺Cause: Volume reduction as concrete dries and cures (internal restraint increases tensile stress).

⏺Severity/repair: Usually non-structural if narrow (<0.3–0.5 mm). Wider cracks may need routing & sealing or epoxy. Control with joints and proper mix/water content.

💫3. Settlement (subsidence) cracks

⏺Appearance: Wider cracks, often at one edge of a slab or wall; may be diagonal or stepped.

⏺Cause: Uneven support/soil settlement under the concrete.

⏺Severity/repair: Can be structural — investigate soil/support. Repair ranges from filling/sealing to underpinning or replacement.

💫4. Thermal cracks

⏺Appearance: Cracks due to temperature gradients — can be random or follow plane of temperature differential.

⏺Cause: Expansion/contraction from temperature changes, especially with poor jointing.

⏺Severity/repair: Often controlled with joints; repair with sealants or overlays if non-structural.

💫5. Structural (overload) cracks — flexural & shear
Appearance:

⏺Flexural: Vertical cracks at mid-span of beams/slabs, perpendicular to tensile stress.

⏺Shear: Diagonal cracks near supports.

⏺Cause: Loads exceeding design capacity or reinforcement failure.

⏺Severity/repair: Potentially serious — require structural assessment.

⏺Repairs: strengthening (carbon fiber, steel plates), additional reinforcement, epoxy injection for non-moving cracks, or member replacement.

💫6. Map or pattern cracking (crazing)

⏺Appearance: Very fine, shallow network of surface cracks (looks like crazing or a map).

⏺Cause: Rapid drying of surface or improper finishing (too much water on surface).

⏺Severity/repair: Mostly cosmetic — surface treatments, overlays, or sealers. Prevent with proper finishing and curing.

💫7. Alkali–Silica Reaction (ASR) / reactive aggregate cracking

⏺Appearance: Random map-like cracking, often accompanied by a gel exudate and expansion.

⏺Cause: Chemical reaction between alkalis in cement and reactive silica in aggregates + moisture.

⏺Severity/repair: Can be progressive and structural. Mitigation requires diagnosis; repair options limited — control moisture, use inhibitors, or replace affected concrete.

💫8. Corrosion-induced cracking

⏺Appearance: Cracking and spalling from reinforcement locations; rust stains common.

⏺Cause: Corrosion of steel rebar expands and cracks surrounding concrete.

⏺Severity/repair: Serious — needs exposure and repair of corroded steel, corrosion protection, patching, or replacement.

💫9. Freeze–thaw damage cracks

⏺Appearance: Rough, scaling, and small cracks over time; surface delamination.

⏺Cause: Freeze–thaw cycles in saturated concrete without proper air entrainment.

⏺Severity/repair: Prevent with air entrainment and proper air-void system; repair by resurfacing or replacing damaged areas.

💫10. Construction / cold-joint cracks

⏺Appearance: Crack at plane where fresh concrete was placed against hardened concrete — often vertical/linear.

⏺Cause: Lack of bond due to delays in placement.
Severity/repair: Can be non-structural or allow water ingress. Repair by cleaning and sealing, grout injection, or dowel installation.

💫11. Curling / warping cracks
Appearance: Cracking at slab corners/edges; slabs lift or curl at edges causing diagonal cracks.

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