Synthesis of geopolymer mortar incorporating date palm ash

The abundance of date palm trees in Saudi Arabia generates a sizable quantity of agricultural waste annually, including midribs, fronds, leaves, stems and coir. Date palm waste is either discarded as landfill or burned on local farms; very little of the waste is utilized. This study was conducted in an effort to promote an alternative waste-management option that aims to reduce or eliminate its negative impact and exploit the economic opportunity of recycling the waste into valuable engineering construction products. In this context, date palm ash (DPA) generated from palm tree waste was employed to produce an alternative, more sustainable and green binder material utilizing geopolymer or alkali-activated composites. To achieve these objectives, six metakaolin (MK) based geopolymer mixes were synthesized with DPA replacing 0 %, 10 %, 20 %, 30 %, 40 % and 50 % by weight of MK. The impact of the DPA on the fresh and hardened characteristics of the mortar was comprehensively studied, including setting time, flowability, mechanical properties at various curing ages and conditions, microstructure and thermal performance at elevated temperatures. It was observed that DPA significantly improved the flowability of MK-based geopolymer mixes, and also accelerated the setting time. Also, DPA positively improved the mechanical properties at room temperature and after exposure to 600 degrees C compared to mixes containing 100 % MK. Due to the presence of highly reactive silica and alumina in the source materials, SEM analysis revealed that the addition of DPA to the mortar caused structural alterations in the geopolymer mortar that could be linked to the formation of packed and dense matrix.