Strength of Binary and Ternary Blended Cement Pastes Containing Palm Oil Fuel Ash and Metakaolin Exposed To Sodium SulphateMohd Hanif Ismail, Nor Hazurina Othman, Ahmad Zurisman Mohd Ali, Megat Azmi Megat Johari and Kamar Shah AriffinMATEC Web Conf., 103 (2017) 01001DOI: https://doi.org/10.1051/matecconf/201710301001