Study on the effect of 5/20 and 20/80 °C temperature cycle curing regimes on the properties of polyacrylate dispersion-modified cement mortar

Abstract

Polyacrylate dispersion-modified cement mortar (PMCM) has been widely studied as a good repair material, but the majority of studies have focused on the curing conditions with constant temperature, while the temperature of its application environment usually varies with time. Therefore, for the variable temperature environment that PMCM may suffer in winter and summer, the mechanical and deformation properties of PMCM and the mechanical properties of polyacrylate dispersion (PA) were investigated by simulating the winter and summer curing regimes through low-temperature cycles of 5 and 20 °C (5/20 °C) and high-temperature cycles of 20 and 80 °C (20/80 °C). XRD, TG-DSC and MIP were used to characterize the microscopic properties and explain the mechanism. In addition, 5, 20 and 80 °C were set as control curing temperatures. The results show that PMCM under 5/20 °C has a higher porosity and greater drying shrinkage compared to 5 and 20 °C, but strength and hydration degree are between the two curing regimes. Compared with 20 °C, the high-temperature stages of 20/80 and 80 °C promote the hydration of the mortar but increase drying shrinkage and porosity, reducing its strength. However, both regimes, especially 20/80 °C, allow the mechanical properties of PA to be enhanced, causing an increase in the cohesion of the modified mortar, which not only compensates for the disadvantages of large porosity but also further increases the strength, indicating that PMCM not only resists the effects of high-temperature cycling or high-temperature environments on strength but even performs better.