Cracking of plastic concrete

Abstract The ACI recommendations for the prevention of the cracking of plastic concrete by limiting the evaporation rate from exposed surfaces are reviewed, and are shown to overestimate the evaporation from the surface of desiccated concrete. Pore moisture effects in desiccated concrete and the stresses arising from these effects are described. The stresses due to desiccation of early age concrete and its strength are compared, and crack initiation and propagation associated with these stresses are discussed. It is shown that ambient conditions conducive to cracking in early age concrete are encountered everywhere, and that, under favourable conditions, shallow cracks in desiccated concrete can propagate almost instantaneously to considerable depths.