Shrinkage Cracks In Concrete Walls

They typically emanate from a corner of a window beam pocket or other opening.

Shrinkage cracks in concrete walls. They expand when they absorb the moisture and shrink when they dry. Plastic shrinkage concrete cracks when concrete is still in its plastic state before hardening it is full of water. Hairline cracks in concrete. This shrinkage causes forces in the concrete which literally pull the slab apart.

Cracks of this type are called reentrant cracks. The bottom line is a low water to cement ratio is the number one issue effecting concrete quality and excess water reduces this ratio. This is the main cause of concrete shrinkage cracks on drying. Diagonal diagonal cracks can form for the same reasons vertical cracks do.

Hairline cracks are commonly observed in freshly placed concrete and their occurrence is owed to the phenomenon of plastic shrinkage. Jagged cracks stair step cracks and 45 degree angle cracks generally signify structural movement or settling issues that are occasionally serious but usually harmless. Vertical and horizontal cracks in drywall or plaster walls typically indicate drying and shrinkage which is normal after construction. Concrete slabs can shrink as much as 1 2 inch per 100 feet.

Concrete and mortar are porous in their structure in the form of inter molecular space. When that water eventually leaves the slab it leaves behind large voids between the solid particles. If you notice a diagonal crack in addition to wall bowing you likely have split supports in your walls. These empty spaces make the concrete weaker and more prone to cracking.

Shrinkage cracks concrete once poured starts hardening and shrinking a little causing shrinkage cracks. These are very common and unless they leak or show signifi cant lateral displacement are of no structural concern. Shrinkage cracks such as shown in our photograph above are found in poured concrete are easily recognizable and can be distinguished from other types of cracks that occur later in the life of a foundation wall or floor slab as we explain here. Shrinkage restraint cracking resulting from shrinkage can occur in concrete masonry walls because of drying shrinkage temperature fluctuations and carbonation.

If a diagonal crack appears near a door or window you can blame it on concrete shrinkage as with vertical cracks. Shrinkage cracks in concrete occur due to change in moisture of concrete. Cracks are the end result of these forces. These cracks are usually considered normal and generally not a great concern however they can be a warning sign of problems.