Curling Of Concrete Floor Slabs

Such curling seriously affects the operation of an industrial facility.

Curling of concrete floor slabs.

Founded in 1904 and headquartered in farmington hills michigan usa the american concrete institute is a leading authority and resource worldwide for the development dissemination and adoption of its consensus based standards technical resources educational programs and proven expertise for individuals and organizations involved in concrete design. 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. This data sheet is concerned only with curling in slabs and particularly slabs on ground. Breaks of the slabs when applying loads on the edges which are literally flown on the base of the pavement.

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. Slab edges can chip off when they curl up or entire slabs can crack in half when the edges curl down. Level change between slabs which effect to the passage of vehicles especially noticeable with small and hard wheels. 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.

Curling is a phenomenon that occurs in concrete slabs lifting the edges of them and causes problems such as. The american concrete institute. 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.

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. Curling is the distortion of a slab into a curved shape by upward or downward bending of the edges. Certain types of breathable sealers or coatings on slabs can work to minimize moisture differentials and reduce curling. Curling of concrete slabs.

The occurrence is primarily due to differences in moisture and or temperature between the top and bottom surfaces of a concrete slab. Reinforcing steel placed near the top surface of the slab can help restrain curling. 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. It may be evident in concrete elements other than slabs eg wall panels.

It is caused primarily by loss of moisture from the concrete surface as the con crete dries. When concrete slabs on grade curl the curling sometimes has little effect on floor performance.