Utilisation of olive waste ash in mortar mixes

Huge amounts of olive waste residues are accumulated every year in olive-oil-producing countries, making an environmental impact. This study investigates the utilisation of olive waste ash in mortar mixes to reduce the environmental pollution arising from olive waste residue. Three olive waste ash levels were considered in the study: 5, 10 and 15%. The other experimental parameters investigated in the study were: replacement type (cement or sand), curing type (moist and autoclaving) and aggregate type (silica and limestone sand). The properties investigated in the study include: fresh properties (workability and setting time), mechanical properties (compressive and flexural strength) and microstructure of mortar. The mortar mixture proportions were 1: 3: 0.7 by weight for cement, sand and water, respectively. The results showed that the setting time and workability of mortar decreased with increasing the olive waste ash content. The mechanical properties of mortar increased with increasing the olive waste ash content as a partial replacement for the sand. On the other hand, the compressive and flexural strength of mortar decreased when more cement was replaced with olive waste ash. The mechanical properties of olive waste ash mortar using silica sand showed higher values compared to those using limestone sand. Scanning electron microscopy images show that the hardened matrix of mortar containing 15% olive waste ash as a partial replacement for silica sand was denser and had a more homogeneous microstructure in comparison with the reference and mortar mixes with olive waste ash as cement replacement.