Water Absorption in Cementitious Materials at Different Temperatures

This paper presents results from an experimental investigation that assessed water absorption in cementitious materials at different temperatures. This work aims to determine whether the absorption behavior may be explained by considering only temperature related variations in the fluid properties (surface tension, viscosity, and density). The calculated water absorption curves at 5°C and 40°C (based on adjusting the absorption that was measured at 23°C using the temperature dependent fluid properties) exhibit agreement with the experimental data for the secondary sorption. This indicates that the change of fluid properties as a function of temperature is the primary reason for the difference in behavior. As a result, it appears possible to predict the rate of secondary absorption of cementitious materials at various temperatures with a simple correction. The initial sorptivity also showed a temperature dependency; however, the dependency of the mortars with water-to-cement ratios of 0.30 and 0.50 was 50 % and 64 % greater than that obtained using only the temperature dependent fluid properties. This indicates that, in addition to variations in the properties of the fluid, the interaction between the fluid and cementitious materials may also have a temperature dependence that influences the initial sorptivity. The transition between initial and secondary sorption (i.e., nick point) occurs at an earlier time with increasing temperature due to the increased rate of fluid absorption.