Pore Structure of Calcium Sulfoaluminate Paste and Durability of Concrete in Freeze–Thaw Environment

Abstract

Mercury intrusion and nitrogen sorption porosimetry were employed to investigate the pore structure of calcium sulfoaluminate (CS¯ A) and portland cement pastes with cement-to-water ratio (w/c) of 0.40, 0.50, and 0.60. A unimodal distribution of pore size was drawn for CS¯ A cement pastes, whereas a bimodal distribution was established for the portland cement pastes through analysis of mercury intrusion porosimetry. For the experimental results generated by nitrogen sorption porosimetry, the CS¯ A cement pastes have a smaller and coarser pore volume than cement paste samples under the same w/c condition. The relative dynamic modulus and percentage weight loss were used for investigation of the concrete durability in freeze–thaw condition. When coarse aggregate with good freeze–thaw durability was mixed, air entrained portland cement concrete has the same durability in terms of relative dynamic modulus as CS¯ A cement concrete in a freeze–thaw environment. The CS¯ A cement concrete with poor performance of durability in a freeze–thaw environment demonstrates the improved durability by 300 % over portland cement concrete. The CS¯ A concrete with good performance aggregate also exhibits less surface scaling in a freeze–thaw environment, losing 11 % less mass after 297 cycles.