Optimizing the Selection of Palm Oil Fuel Ash as Cement Replacement Through Physicochemical Characterizations and Pozzolanic Activity Assessment

Palm oil fuel ash (POFA) has shown suitability as a supplementary cementing material (SCM) in mortar and concrete. However, variations in the physicochemical compositions of POFA, resulting from differences in burning conditions, may impact its desired properties as an SCM. Hence, this paper presents findings on physicochemical characteristics and pozzolanic properties of POFA obtained from different sources to optimize the quality of POFA as SCM. Five POFA from different mills were labeled as POFA1, POFA2, POFA3, POFA4, and POFA5. Characterizations were done using X-ray fluorescence, X-ray diffraction, Fourier transformed infrared, and field emission scanning electron microscopy—energy dispersive X-ray samples from five sources. Pozzolanic activities of POFA specimens were evaluated using ASTM C618 strength activity index (SAI) and electrical conductivity test. The results indicate that variations in the physicochemical characteristics of POFA from different sources are not significant. Yet the various chemical compositions especially silica and alumina content could contribute its pozzolanicity. The relative loss in conductivity shows POFA1 has a better pozzolanic activity compared to other POFA specimens. However, all specimens surpassed the minimum strength requirement (75%) in the SAI test, suggesting that regardless of the burning conditions at palm oil mills, the resulting POFA can be used as an SCM.