Curling Of Concrete Floor Slabs

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.

Curling of concrete floor slabs.

Slab edges can chip off when they curl up or entire slabs can crack in half when the edges curl down. There are occasions however when curling isn t tolerable and repairs are needed. 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.

This data sheet is concerned only with curling in slabs and particularly slabs on ground. When concrete slabs on grade curl the curling sometimes has little effect on floor performance. Reinforcing steel placed near the top surface of the slab can help restrain curling. 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.

Breaks of the slabs when applying loads on the edges which are literally flown on the base of the pavement. Curling is a phenomenon that occurs in concrete slabs lifting the edges of them and causes problems such as. It is caused primarily by loss of moisture from the concrete surface as the con crete dries. The effect of curling on floor serviceability varies depending on the intended use.

Curling is the distortion of a slab into a curved shape by upward or downward bending of the edges. 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. Certain types of breathable sealers or coatings on slabs can work to minimize moisture differentials and reduce 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. 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. Level change between slabs which effect to the passage of vehicles especially noticeable with small and hard wheels. Curling of concrete slabs.

Such curling seriously affects the operation of an industrial facility. 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.