A comprehensive review of sustainable geopolymer concrete using palm oil clinker: environmental and engineering aspects

Amidst the dual challenges of aggregate scarcity and the environmental impact of carbon dioxide (CO₂) emissions from cement production, this study investigates the viability of palm oil clinker (POC) as a sustainable aggregate in geopolymer concrete (GPC). The lack of appropriate alternative coarse and fine aggregates essential in concrete production is one of the critical issues faced by the construction industry. This review evaluates its environmental benefits, chemical and physical attributes, and influence on GPC's microstructure. Previous studies have shown that incorporating POC in GPC significantly reduces density from 2345 to 1821 kg/m³ while maintaining competitive compressive strength, thus proving its applicability in various structural and nonstructural contexts. Moreover, GPC with POC demonstrates enhanced resistance to aggressive environmental conditions such as water absorption and resistance against acid and sulfate environments. Geopolymer mortar (GPM) exposed to sulfate attack recorded the lowest decrease in strength than GPM containing POC fine aggregates by about 20%. The use of 100% POC aggregates in GPC mix has a 3.2% water absorption, which is lower than the limit for high-performance concrete. The results advocate for the development of POC-aggregate GPC as an environmentally friendly construction material, contributing to the sustainable advancement of the building industry.