Effectiveness of Soy Methyl Ester-Polystyrene as a Concrete Protectant on Mitigating the Chemical Interaction between Cement Paste and Calcium Chloride

Abstract

Concrete pavements and bridge decks suffer from severe deterioration caused by the application of chloride-based deicing salts (i.e., NaCl, CaCl2, and MgCl2) during winter. One of them is the formation of a destructive calcium oxychloride (CAOXY) phase caused by the chemical interaction between cement paste and CaCl2/MgCl2. By simulating the practical service conditions, this work investigated the formed CAOXY phase in cement paste exposed to CaCl2 solution and evaluated the performance of soy methyl ester-polystyrene (SME-PS) blend as a promising concrete protectant in mitigating the formation of CAOXY. With the surface treatment of SME-PS, cement paste showed less than 10% of the formed CAOXY phase in control cement paste after being exposed to CaCl2 solution for 28 days. In control cement paste, the amount of formed CAOXY at the exposed surface increased with the exposure time and some of the CAOXY phase formed in the cement paste exhibited a higher phase changing temperature. Moreover, a modified model based on Fick’s second Law was developed for predicting the CAOXY content in concrete with respect to the depth of the exposed surface. This model was verified by the comparison between the predicted values and the data obtained from a low-temperature differential scanning calorimetry (LT-DSC) test.