An experimental study of early thermal cracking in reinforced concrete

Abstract

Synopsis Restrained volume changes in concrete can cause cracking before normal service loads are applied, since all concrete members undergo an early thermal cycle due to the heat of hydration. This mechanism of early thermal cracking is reviewed and an experimental laboratory investigation is described which tested the validity of the current proposals in BS 5337 for some different types, arrangements and amounts of reinforcement. Of the types of reinforcement investigated, the fabric was found, as expected, to give the best crack width control. It was confirmed that, provided a minimum ratio of reinforcement is present in reinforced concrete, thermal crack widths are a function of reinforcement ratio, reinforcement diameter, strength of concrete and bond strength between reinforcement and concrete.