Curling Of Concrete Floor Slabs

Reinforcing steel placed near the top surface of the slab can help restrain curling.

Curling of concrete floor slabs. The moisture loss occurs in all envi ronments at less than 100 relative humidity and is typically more severe in areas of low relative humidity. The effect of curling on floor serviceability varies depending on the intended use. Placing 4 bars on 18 inch centers both ways and chairing the bars to keep them within an inch of the surface has been suggested see controlling curling and cracking in floors to receive coverings concrete construction july 1998 pp. Curling is a phenomenon that occurs in concrete slabs lifting the edges of them and causes problems such as.

Level change between slabs which effect to the passage of vehicles especially noticeable with small and hard wheels. It is caused primarily by loss of moisture from the concrete surface as the con crete dries. If the total curl is less than 1 4 inch or curling occurs primarily in low traffic areas or under storage racks the owner can often live with it provided that cracking isn t excessive. There are occasions however when curling isn t tolerable and repairs are needed.

Curling of concrete slabs. This curling effect can lift the edges or the middle of the slab leaving an unsupported portion of the concrete which can then crack and break when weight is applied. Achieving such surfaces in floor slabs however is quite difficult because of the moisture and temperature gradients that cause them to curl at the joints. Such curling seriously affects the operation of an industrial facility.

It may be evident in concrete elements other than slabs eg wall panels. This data sheet is concerned only with curling in slabs and particularly slabs on ground. Slab edges can chip off when they curl up or entire slabs can crack in half when the edges curl down. Floors subjected to heavily loaded forklift traffic may rapidly deteriorate causing safety problems.

When curling in a concrete slab application cannot be tolerated alternate options include the use of shrinkage reducing admixtures shrinkage compensating concrete post tensioned slab construction and vacuum dewatering. Certain types of breathable sealers or coatings on slabs can work to minimize moisture differentials and reduce curling. The american concrete institute. The occurrence is primarily due to differences in moisture and or temperature between the top and bottom surfaces of a concrete slab.

Breaks of the slabs when applying loads on the edges which are literally flown on the base of the pavement. The upward or downward movement of a concrete slab s corners or edges due to moisture and or temperature differentials within the concrete is known as curling or warping.