Combined effect of expansive and shrinkage reducing admixtures to control autogenous shrinkage in self-compacting concrete

Abstract

Self-compacting concrete possesses special properties that recommend its application in many repair jobs. However, in some practical cases, inappropriate performance of the repair material has been observed in the early stages of hydration, including cracks or delamination due to shrinkage. This study presents laboratory test results on the autogenous shrinkage of self-compacting concrete. Taking into account the typically high autogenous shrinkage of concrete mixtures with low W/C, associated with this type of concrete, the efficiency of different shrinkage-compensating products was evaluated. Two shrinkage reducing admixtures and one expansive binder have been studied.The results show the efficiency of the individual use of each product and put in evidence a synergistic effect on the autogenous shrinkage reduction when shrinkage reducing admixture and expansive agent were combined.The results also show a potential for achieving a predefined shrinkage range, by using the combined effect of a set retarder and an expansive admixture.