Shrinkage of concrete - Plastic, Drying and Thermal shrinkage
Shrinkage of concrete means volumetric change in concrete which affects the long term strength and durability of concrete. It is an inherent property of concrete. It appears in form of cracks. Shrinkage of concrete is classified in three category - Plastic shrinkage Drying shrinkage Thermal shrinkage Plastic shrinkage - This type of shrinkage occurs when concrete is in plastic stage or we can say it occurs just after the concrete is placed. Plastic shrinkage takes place due to loss of water by evaporation or absorption by aggregate. poorly made concrete with high water - cement ratio. unintended vibration or yielding of formwork. extreme bleeding at the same time rapid drying. Plastic shrinkage crack can be reduced by preventing the rapid loss of water on surface. This is done by covering the surface with polythene sheet after placing the concrete immediately. by working at night. by applying mono-molecular coating by fog-spray. Drying shrinkage - After placing the concrete, it un