Recycling of volcanic ash and carbide slag in blended mortars: A multi-criteria performance assessment

Abstract

A multi-criteria performance evaluation was performed to assess the physical and durability properties of cementitious composites containing volcanic ash (VA) and carbide slag (CS). The investigated mortars involved cement mass substitution by VA at 0–40 % and CS at 0–20 %. Mortar mixes with these respective substitution rates were examined for compressive strength, fresh and hardened densities, water transport properties, electrical resistivity, abrasion resistance, calcium leaching potential, and sulfate attack resistance. The Technique for Order of Preference by Similarity to the Ideal Solution (TOPSIS) was utilized to rank the mortar mixes and select VA and CS percentages for superior physical and durability performance. The TOPSIS model was also verified through a sensitivity analysis. Regression relationships were determined between different properties to validate and link the outcomes. The outcomes showed that substituting cement with VA at 10–20 % and CS at 0–5 % by mass, either solely or synergically, improved the performance of the mortar. CS incorporation alongside VA improved all properties except the resistance to aggressive environments. These findings highlight that it was possible to replace cement by up to 25 % by mass while achieving superior physical and durability performance, owing to the filler effect of the alternative binders, enhanced pozzolanic reaction, and wide-ranging particle size offered by the ternary system. This study contributes to the collective effort to create sustainable and low-carbon cementitious composites using alternative binders while also aligning with United Nations Sustainability Development Goals (SDGs), particularly SDG 9 (Infrastructure Resilience), SDG 12 (Waste Management), SDG 13 (Climate Change Mitigation and Adaptation).