Predictions and verifications of early-age stress development in hydrating blended cement concrete

A procedure for calculating the early-age stress development in concrete incorporating the aging viscoelastic effects is presented in this paper. The important features of the present procedure are the use of tensile creep and inclusion of heat of hydration. The latter is used as an aging parameter and incorporates the effect of temperature on age-dependent material parameters. To validate stress predictions, experiments to measure early-age stress development in concrete mixes made of blended cements were conducted. The predictions were found to be accurate and could be improved when the effect of temperature was included. Effects of using mineral additives (fly ash, slag, and silica fume) appeared to be beneficial in reducing the risk of cracking at early ages. The effect of temperature gradient was also studied when the stress calculation was applied to pavement or foundation slabs resting on a very stiff subgrade.