Adding ground sand to decrease paste volume, increase cohesiveness and improve passing ability of SCC

Abstract

In the production of SCC (self-consolidating concrete), it is not easy to achieve high passing ability without sacrificing other performance attributes because the common practice of increasing the cementitious paste volume to achieve high passing ability would decrease the dimensional stability and increase the carbon footprint. In fact, at narrow gaps, the paste often flows in the front leaving the coarse aggregate particles behind to block the subsequent flow of concrete, especially if the paste does not have good cohesiveness. Hence, increasing the paste volume is not always effective in increasing the passing ability. Herein, it is proposed to keep the paste volume small and add ground sand with a mean size of 0.3mm to increase the mortar volume and cohesiveness, and improve the passing ability. Trial concrete mixes with paste volumes of 30% and 34% and different ground sand contents have been tested and the results demonstrated that the addition of ground sand would enable the achievement of high passing ability at a relatively small paste volume.