Conventional Portland Cement and Carbonated Calcium Silicate–Based Cement Systems

Abstract

The behavior of two cementitious materials during thermal changes associated with freezing and thawing in presence of calcium chloride deicing salts was examined. The two systems consisted of a conventional portland cement-based material and an alternative economically friendly cement that formed a solid by carbonating a calcium silicate–based cement. Low-temperature differential scanning calorimetry was used to quantify the phase changes associated with ice formation, eutectic solution transformation, and calcium oxychloride formation. Longitudinal guarded comparative calorimetry was used to detect the damage that developed as a result of the expansive pressures created by these phases when they form. In both systems exposed to low salt concentration, the damage was primarily caused by hydraulic and osmotic pressure. This type of damage was moderate at low degrees of saturation (e.g., <90%); however, as the degree of saturation increased, so did the damage. In conventional cementitious systems at higher salt concentrations, the damage that developed was mainly caused by the formation of calcium oxychlorides. However, in the cementitious materials made by carbonating calcium silicate–based cement calcium, hydroxide was not present. Therefore, at higher salt concentrations, calcium oxychloride did not form, and as a result, no damage developed.