How To Prevent Craze Cracking On Concrete Floors

Craze cracking of concrete floors is caused by the shrinkage of the cement paste on the surface, and is particularly noticeable when the concrete slabs are damp. But there are certain steps to take to prevent floors displaying this unsightly appearance, says Bryan Perrie, MD of The Concrete Institute. Perrie says factors the promote crazing of concrete floors include: • Drying instead of curing before the floor develops much strength, particularly after hard trowelling; • Curing with water much colder than the concrete, causing thermal shock; • Alternating wetting and drying at early stages; • Overusing vibrating screeds and bull floats; • Overworking and over-trowelling, especially when the surface is wet; • Floating and trowelling prematurely; • Dusting dry cement onto the surface before trowelling; • Using aggregates with excessive clay and dirt; and • Applying water to the surface during finishing operations.