Research on the effect of relative humidity on the electromagnetic performance of long-cured tricalcium silicate cement paste: Water action and phase evolution

Abstract

This research investigates the electromagnetic properties as well as the microscopic mechanisms of tricalcium silicate (C3S) pastes maintained for a long time at different relative humidities (RH). The electromagnetic transport properties and electromagnetic parameters of undried and dried specimens of C3S paste specimens cured for 180 d at four RHs were tested for microscopic property changes. The results show that the water content significantly affects the electromagnetic properties of the specimens. With the increase of RH, the electromagnetic wave reflectivity and absorption of the specimens increased and the transmission decreased. Based on the changes in microphase properties it was found that the hydrated calcium silicate (C-S-H) gel had the greatest effect on the electromagnetic properties of C3S paste. In addition, the increase in RH also resulted in a significant increase in the volume percentage and area percentage of mesopores in the specimens, which in turn increased the electromagnetic wave loss. This study provides a microscopic explanation for analyzing the effect of RH on the electromagnetic transmission properties of cementitious materials.