Chemical and freeze-thaw resistance of fly ash-based inorganic mortars

Inorganic cements have many advantages over Portland cement including energy efficiency, reduced greenhouse gas emissions, rapid strength gain, and improved temperature resistance. Alkali activated cements made from waste materials such as fly ash, are particularly advantageous because of their environmental sustainability and low cost. However, their long term durability is yet to be confirmed. In this study, the chemical and freeze/thaw resistance of fly ash based inorganic mortars was investigated. Specimens of various compositions were tested to determine their chemical and freeze-thaw resistance. Chemical resistance of samples was evaluated by immersion in 5% sodium sulfate solutions, 3% sulfuric acid solutions, and 0.05% sulfuric acid solutions, respectively, for up to 24 weeks. The changes in mass, dynamic modulus, strength of the specimens, and the pH values of the solutions were monitored at regular time intervals. Test results are presented and discussed in conjunction with the companion results of ordinary Portland cement (OPC) mortars.