Influence of mix proportions, plasticizers and superplasticizers on creep and drying shrinkage of concrete

Abstract

The influence of plasticizing and superplasticizing admixtures on long-term deformations of concrete is reassessed. An approximate method is proposed to allow for changes in mix proportions when the admixtures are used as water and cement reducers, so that the influence on deformations is isolated from the influence of water/cement ratio and cement paste content. For five types of admixture, there is a general increase in both creep and shrinkage of between 3% and 130%, but limited data and variability indicate no conclusive differences between types of admixture or between types of deformation. In the absence of specific test data, it is suggested that, for admixture flowing concrete, deformation should be increased by 20%. For other applications of admixtures involving changes in mix composition, deformation can be estimated by the proposed method.