Plastic shrinkage cracks in concrete and the Preventive measures for Plastic Shrinkage Cracks

Plastic shrinkage cracks in concrete and It's Preventive measures 

Plastic Shrinkage Crack 

When finish concrete is subjected to a rapid loss of moisture from its surface this type of crack observed. These cracks are not very deep (20 to 25 mm) and long (200 to 500 mm long) and can affect a large portion of the concrete surface. 

Causes of Plastic Shrinkage Crack :

Plastic shrinkage crack is the result of high shrinkage (reduction in volume) of the upper surface of concrete from its underlying layer.

• Ambient concrete temperature and low relative humidity. 
• Very windy weather
• Finishing of concrete surface with rich cement 
• Excess amount of sand in concrete 
• Improper curing

Preventive Measures for Plastic Shrinkage Crack:

• Early curing of concrete (after final set)
• Spraying of curing compounds / fog-spray immediately after finishing.
• Providing windbreaks to decrease the wind velocity.
• Covering the surface with think tarpaulin sheet or sunshades to reduce the temperature.
• Discouraging over sanded mix