Influence of cajuput leaf residue on the properties of lightweight expanded clay aggregate

This study investigates the utilization of solid residue from Melaleuca cajuputi leaf distillation as an additive in the production of lightweight expanded clay aggregate (LECA). Cajuput leaves are known for their essential oil applications. After oil extraction, they leave behind a solid waste, which has not been widely explored for further applications. In this research, cajuput leaf residue was mixed with clay at varying ratios (0%–40%) and sintered at different temperatures (700, 800, and 900 °C) to evaluate its effects on the LECA's physical and chemical properties. The results indicate that increasing the cajuput leaf residue content led to a decrease in bulk density while significantly enhancing porosity and water absorption. The optimal ratio was found to be 40% cajuput leaf residue sintered at 800 °C. This composition exhibited the highest porosity (78.29%) and water absorption (110.7%), making it particularly suitable for plant growth applications. SEM and EDS analyses confirmed the formation of a microporous structure with the key elements being oxygen, silicon, aluminum, and iron. Higher sintering temperatures reduced porosity due to increased densification. These findings highlight the potential of cajuput leaf residue as a sustainable raw material for producing eco-friendly LECA, particularly for horticultural applications.