Concrete Shrinkage

Shrinkage is the reduction of concrete volume due to the settlement of solid and loss of moisture.

Plastic shrinkage commonly occurs in slab and pavement, types of structure that has large surface area. In this case, as soon as the concrete is casted, water may escape to the atmosphere via evaporation. Subsequently, the volume of cement-water system (plastic concrete) reduced and premature cracking is developed.

Drying shrinkage occurs in hardened concrete. It is caused by the loss of surface-absorbed water in cement gel, as well as the hydrostatic tension in small pores. Drying shrinkage is a gradual process, and its rate of shrinkage usually decreases with time. Cracks will be developed when such shrinkage is restrained.