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Construction related cracks

Various types of cracks may be formed during the construction process and changes within the young concrete. The main types are Plastic shrinkage cracks, Plastic settlement cracks, Thermal contraction cracks, Crazing, Long term drying shrinkage cracks and Cracks at joints. The time at which the crack forms will give an indication of the cause, as shown in the Table.

Type Typical time of appearance
Plastic shrinkage cracks Thirty minutes to six hours
Plastic settlement cracks Ten minutes to three hours
Thermal contraction cracks One day to two or three weeks
Crazing One to seven days, sometimes longer
Long-term drying shrinkage cracks Several weeks or months
Cracks at joints One day or two or three months

The occurrence of many of these cracks can be reduced or eliminated by good construction techniques; guidance is given for each type of crack.

Typical crack
Acknowledgement: Concrete Society

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TR54 Diagnosis of deterioration in concrete structures- identification of defects, evaluation an

Shrinkage of concrete

Crack width measurement