Modelling of early age tensile strain development of fresh concrete

Plastic shrinkage cracking is a common phenomenon associated with concreting in hot and windy weather. Excess evaporation of bleed water causes loss of water from the concrete surface and plastic shrinkage occurs due to that at very early stage i.e. within the first 4-6 hours. Tensile strain will be developed as a result of this shrinkage and cracking will occur when it exceeds the tensile strain capacity of concrete. This paper is aimed at developing a model to simulate such behavior and determine the tensile strain development with time. First, key factors affecting shrinkage, bleeding and evaporation, were modelled and the starting time of drying was identified. Subsequent loss of water was calculated and incorporated in a finite element model to simulate the tensile strain development. Calculated strains were very similar to the measured strains and therefore the model can be used to accurately predict the development of early age tensile strain due to plastic shrinkage.