Effect of Fly Ash on Early-Age Tensile Creep, Shrinkage, and Cracking Resistance of Supersulfated Cement Concrete under Uniaxial Restrained Condition

Supersulfated cement (SSC) has been utilized to substitute for portland cement to reduce the carbon dioxide emissions and energy consumption caused by the production of portland cement. Improving the durability of concrete reduces the maintenance cost of buildings, and cracking resistance is a critical parameter in the evaluation of concrete durability. Tensile creep and shrinkage play a crucial role in assessing the cracking tendency of concrete. However, research on the impact of fly ash (FA) on the hydration evolution, autogenous shrinkage (AS), tensile creep, and cracking resistance of SSC concrete remains lacking. Thus, understanding the tensile creep and shrinkage facilitates the evaluation and control of the cracking behavior of SSC concrete. Researches on the hydration evolution, AS, tensile creep, and cracking resistance of SSC concrete activated by calcium sulfoaluminate with different contents of FA (0%, 15%, 30%, and 50% by replacing cement mass) were carried out. Moreover, the mechanical properties and hydration evolution tests were also conducted. Experimental results demonstrated that incorporating FA reduced both the hydration heat and AS of SSC concrete, whereas the tensile creep increased with increasing dosages of FA. Incorporating FA decreased the compressive strength and enhanced the cracking resistance of SSC concrete. The cracking potential calculated by an integrated criterion decreased by 11.53%, 16.64%, and 30.36% with the dosages of FA increasing from 0% to 15%, 30%, and 50%, respectively.