A small amount of temperature steel reinforcement will reduce the width of cracks that do occur.The type and amount of cement, as well as course and fine aggregates, can also have a large effect on the amount of shrinkage. A mix with sufficient strength using the minimum amount of water necessary to distribute the concrete throughout the wall without voids should be used. The first is the use of proper concrete mix designs.With these cracks it is very likely that the crack itself is not the problem, but rather the result of an external problem such as poor drainage, overloading, etc.Ĭontractors can employ several methods of reducing the occurrence and width of cracks. Vertical cracks which are significantly wider at the top or bottom could indicate heaving or settlement. These are very common and, unless they leak or show significant lateral displacement, are of no structural concern.Ĭracks which are horizontal are most likely caused by an applied load. Cracks of this type are called re-entrant cracks. They typically emanate from a corner of a window, beam pocket, or other opening. Shrinkage and Temperature cracks are most often vertical to diagonal. The vast majority of cracks are of little concern by themselves. Each of these causes normally leave a “signature” in the type of crack it creates. When the forces exceed the strength of the material, cracks will develop. Tremendous forces can build up inside the wall due to any of these causes. Applied Stresses-Forces such as building load, earth load, hydrostatic pressure, or heavy equipment operated too close to the wall.Differential Bearing Capacity- Harder soils under part of the foundation can cause stresses as the building “settles in.”.Subgrade Settlement (or Expansion) – Resulting from poor soil conditions or changes in soil moisture content.

Thermal Contraction/Expansion-Due to temperature changes.

Drying Shrinkage-This occurs as water used in the mix design evaporates.

Causes of CracksĬracking can be the result of one or a combination of factors, all of which involve some form of restraint.

Most cracks should not be a cause for alarm. Cracking can not be prevented but it can be significantly reduced or controlled when the causes are taken into account and preventative steps are taken. They appear in floors, driveways, walks, structural beams, and walls. Cracks in concrete walls and slabs are a common occurrence.

Shrinkage cracks in concrete beams