Experimental Investigations on Early-Age Stress Relaxation and Cracking Behavior of Supersulfated Cement Concrete with Different Activator Proportions

As an alternative to ordinary portland cement (OPC), supersulfated cement (SSC) has better properties in terms of being environmentally friendly as well as durability in aggressive environments. Nevertheless, the research on the influence of activator proportion on SSC concrete remains limited, particularly regarding early-age cracking behavior, which still needs further exploration. This research investigated the early-age shrinkage, stress relaxation, and cracking potential of SSC concrete with different activator proportions (14%, 17%, and 20%) under different degrees of restraint. OPC concrete was set as a reference. The results revealed that, as the activator proportion increased, the mechanical properties of SSC concrete were improved and approached or surpassed OPC concrete at a later stage. SSC concrete with a higher activator proportion exhibited lower free shrinkage. In both tests with different ratios of volume to drying surface area, the free shrinkage of SSC concrete was higher than that of OPC concrete. The residual stress and relaxed stress of SSC concrete decreased and increased with the increase of activator proportion, respectively. Additionally, compared with OPC concrete, SSC concrete showed a higher relaxed stress in tests with different degrees of restraint. A higher activator proportion of SSC concrete was beneficial to reduce cracking potential and delay the cracking age in present research. A nonlinear fitting formula was obtained to describe the relation between relaxation and creep coefficients of SSC concrete. The present paper might offer valuable reference for determining the optimal activator proportion for SSC concrete and advance its future application.