EARLY THERMAL CRACKING OF CONCRETE - A CASE HISTORY.

Abstract

An investigation into the cause of cracking of a new railroad station is described. A large number of cracks was discovered upon removal of form-work. The cracks developed in the reinforced concrete beams, some extending into the adjoining slabs above. Structural calculations indicate that the multitude and extent of cracking could not have been caused by the self weight of the concrete beams. Site records show that concreting was carried out in hot weather when the temperature was in the high thirties C (high nineties F). With a rather high cement content, the heat of hydration of cement could have raised the temperature of the concrete 30 C (54 F) above the ambient temperature. When the concrete subsequently cooled down, the thermal movement manifested itself in the form of cracking.