Microstructure and Mechanical Characterization of Alkali-Activated Palm Oil Fuel Ash

Abstract

Pastes and mortars of alkali-activated palm oil fuel ash (POFA) are synthesized with three types of alkaline solutions and are characterized for molecular functional groups by Fourier transform infrared (FTIR) spectroscopy, microstructure observation, and chemical composition by scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and mechanical strength using a universal mechanical tester. The alkali activators chosen for this investigation are 12 M sodium hydroxide (NaOH), 3 M sodium silicate (Na2SiO3), and a combination of both activators (Na2SiO3 and NaOH) by mass ratio of 3∶1. POFA with Na2SiO3 solution yields the highest compressive strength in comparison to the other activators. The main gel binder dominantly composed of silica with varying calcium/silica (Ca/Si) ratios is analyzed by analytical techniques through FTIR and SEM-EDX.