Experimental Study on Thermal Stress of Concrete with Different Expansive Minerals Using a Temperature Stress Testing Machine

In order to compare the compensation effect of expansive materials with different mineral sources on the temperature stress of concrete, we investigated the temperature stress of concrete when adding calcium sulfoaluminate type expansive materials (CSA) or CaO and calcium sulfoaluminate mixed type expansive materials (HCSA) at different temperatures by temperature-stress testing machine (TSTM) considering the influence of temperature history on the expansion. The experimental results show that the expansion characteristics of the two kinds of expansive materials with different mineral sources significantly vary. When adding expansive materials, the growth rate of compressive stress during the heating stage increases obviously, the maximum compressive stress is higher, while the decline rate of tensile stress in the late cooling stage becomes slow, and finally cracking temperature decreases. It is proved that concrete with HCSA has lower cracking temperatures and better temperature shrinkage compensation effect. Therefore, it is rational to choose HCSA when preparing concrete with high expansion energy to reduce thermal cracking.