Chemical Shrinkage of Pastes Made with Shrinkage Reducing Admixtures

Abstract

Abstract. Shrinkage Reducing Admixtures (SRA) are being used more often in concrete structures in order to better control shrinkage cracks. High-performance concrete, nowadays with large application, has more proneness to crack at very early age due to the lower W/C. In this type of concrete, autogenous shrinkage is usually more important than drying shrinkage. Autogenous shrinkage is due to the volume decrease inherent to binder hydration reactions. The rate of these reactions is influenced not only by the type of binder but also by the presence of chemical admixtures. It is recognized that SRA delay the hydration, being a secondary effect of this type of admixtures. In this work changes on the degree of hydration of cement pastes with SRA and different binders are presented, using the chemical shrinkage test.