Category: Structure & materials
Prepared by Eng. Ahmed Fathy, Projects Manager ·
Definition
Concrete cracks fall into plastic cracks appearing in the first hours as the surface dries, shrinkage and thermal cracks, and structural cracks from overload, missing steel or foundation settlement. A crack's direction, width and timing point to its cause.
Why it matters on a project
Most hairline cracks are not dangerous but let water reach and rust the steel. Diagonal cracks near supports, or cracks widening over time, need a structural assessment.
Common mistake
Skipping curing in the Saudi summer, so plastic cracks show on the slab surface on the day of the pour.
Frequently asked questions
When is a crack dangerous?
When it is diagonal near supports, widening over time, or comes with sagging or rust.
How are hairline cracks repaired?
With suitable injection or sealing materials after finding the cause, plus waterproofing on roofs.
Related terms
- CuringKeeping concrete moist and at temperature after pouring so it reaches its design strength.
- Concrete coverThe concrete thickness between the surface and the nearest bar.
- Concrete core testDrilling cylinders from hardened concrete to measure its actual strength.
- Construction jointWhere a pour stops and resumes within one concrete member.
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