Common Causes of Concrete Cracks (and How to Fix Them)

Concrete cracks are one of the most common issues homeowners and property managers face, but not every crack signals a serious problem. Understanding what caused the crack is the key to choosing the right repair method and preventing further damage down the road.

Why Concrete Cracks in the First Place

Concrete is incredibly strong under compression, but it has limited flexibility. When internal stress or external pressure exceeds the material’s tensile strength, a crack forms. Some cracks appear within hours of a pour, while others develop slowly over years. The good news is that most cracks can be repaired effectively when you understand what is happening beneath the surface.

At TurnKey Concrete Team, we evaluate hundreds of cracked slabs, foundations, and walkways every year across Greater New Orleans. Here is a straightforward look at the most frequent causes and what you can do about each one.

Shrinkage Cracks

Shrinkage cracks are the most common type, and they usually appear within the first few days after concrete is poured. As the water in the mix evaporates, the slab contracts slightly. If that contraction is restrained by the subgrade, forms, or reinforcement, hairline cracks develop on the surface. These cracks are typically very thin and shallow, often less than an eighth of an inch wide.

Hot, dry, or windy conditions accelerate moisture loss and increase the risk of shrinkage cracking. In Louisiana, summer pours are especially prone to this because of intense heat. Proper curing techniques, including keeping the surface moist for several days after placement, significantly reduce shrinkage cracking. Our guide on the best time to pour concrete in Louisiana covers timing in detail.

Settlement and Soil Movement

Soil conditions in the Greater New Orleans area are notoriously challenging. Clay-heavy soils expand when wet and shrink when dry, creating a cycle of movement underneath concrete slabs. Over time, this movement can cause sections of a slab to sink unevenly, producing wide structural cracks that run at