Pore structure of hydrated calcium silicates. III. Influence of temperature on the pore structure of hydrated tricalcium silicate

Abstract

Water vapor adsorption isotherms were obtained for samples of tricalcium silicate hydrated for from 1 hr to 28 days at temperatures of 25, 50, 75, and 100°C. The isotherms were used for determination of the BET and S t surface areas and for calculation of pore volume and surface area distributions in both micropores and wide pores. The analytical modification of the “corrected modelless” method was used in the analysis of the wide pores. Micropores were analyzed by the “MP method” using the t-curves of Mikhail and co-workers. At early stages of hydration both the amount of nonevaporable water and the surface area of the samples, per unit of nonevaporable water, increased with the temperature. However, after froml to 3 days, the samples hydrated at lower temperatures had higher nonevaporable water contents and surface areas. The rate of hydration decreased rapidly and, for samples hydrated at 75 and 100°C, the reaction had apparently ceased in less than 28 days. Results of micropore and wide pore analysis were in line with the above findings. However, due probably to the simultaneous occurrence of micropore filling and capillary condensation, no micropores were detected in some of the samples.