Effect of mix design on restrained shrinkage of self-consolidating concrete

This paper presents test results carried out to evaluate the potential due to restrained shrinkage cracking of self-consolidating concrete (SCC). The mix design approach and binder type of the SCC are shown to have considerable influence on cracking potential. Mixtures made with 0.42 w/cm and incorporating viscosity-enhancing admixture (VEA) to ensure proper stability exhibited approximately 25-35% longer time before cracking than SCC prepared with 0.35 w/cm and no VEA. The former concrete design had lower elastic modulus at 3 days when the drying shrinkage was initiated and hence greater stress relaxation. This was reflected in greater tensile creep coefficient which reduces tensile stress due to restrained shrinkage. The SCC made with 0.42 w/cm exhibited slightly higher drying shrinkage after 56 days of drying compared to similar concrete prepared with 0.35 w/cm. In general, the tested SCC mixtures had higher cracking potential than the reference high-performance and conventional concretes. This may be due to the higher paste volume of SCC that resulted in greater drying shrinkage. Mixtures with 670 mm slump flow consistency and 180 mm slump values of the same mix design had similar elapsed times before cracking of 6.3 and 5.6 days, respectively.