CIRIA C660 – Early-age Thermal Crack Control in Concrete

Access free from the CIRIA website.

This guide replaced R91 and has now been superseded by CIRIA C766.

This guide provides a method for estimating the magnitude of crack-inducing strain and the risk of cracking; and where cracking is predicted guidance is provided on the design of reinforcement to control crack widths. For specific situations where cracking should be avoided, or where the use of reinforcement to achieve acceptable crack widths is uneconomic or impractical, measures are described to minimise the risk including selection of materials and mix design, planning pour sizes and construction sequence, the use of insulation to reduce thermal gradients, the use of movement joints, and cooling of the concrete either prior to placing or in situ.