Durability performance of geopolymer cement based on fly ash and calcium aluminate cement in mild concentration acid solutions

The present work evaluates 2-year durability performance of geopolymer cement (GC) mortar derived from a blend of low calcium fly ash and calcium aluminate cement in hydrochloric and sulfuric acid solutions of mild concentration (pH 3). The dry binary blend was activated by a solution of sodium hydroxide and liquid sodium silicate and the GC mortar specimens were cured hydrothermally. At different time intervals of acid attack, the compressive strength and mass loss of specimens were measured and complementary studies on compositional and microstructural changes were performed using X-ray diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy. The results revealed a superior durability performance for GC mortar especially in hydrochloric acid, compared to Portland and high alumina cement mortars used as reference. In addition, all the three cements showed a considerably higher degree of deterioration in exposure to sulfuric acid than in hydrochloric acid.