Performance of slag blended alkaline activated palm oil fuel ash mortar in sulfate environments

This study investigated the performance of alkaline activated ground steel slag-ultrafine palm oil fuel ash (AAGU) mortar exposed to 5% Na2SO4 and 5% MgSO4aq for 6 months. The samples cured at 60 degrees C for 24 h were prepared with 10 M-NaOHaq and Na2SiO3aq (Ms-SiO2/Na2O = 3.3) activators. Microstructural and characterization tools were employed to examine the type and nature of the resulting products. The findings showed that there was a better strength retention in the MgSO4aq-exposed samples compared to the Na2SO4aq exposed due to the formation of surfacial deposits and intra-microstructurally crystallized anhydrite (CaSO4). The loss of weight/strength and skeletal disintegrations in Na2SO4aq exposure resulted from the leaching of active elements (Ca, Al and Mg). Slag significantly contributed to the sulfate resistance of AAGU mortars, while there was an insignificant difference in strength retention when the activator ratios (Na2SiO3aq:NaOHaq) varied within 1.0-2.5 for the samples prepared with a workable mixture. (C) 2015 Elsevier Ltd. All rights reserved.