Effect of apricot kernel ash on the performance of sustainable alkali-activated composites

Abstract

Due to environmental protection policies and the scarcity of natural resources, biomass has become an important renewable energy source. Apricot kernel ash (AKA) as a novel biomass ash was used to partially replace metakaolin to produce an alkali-activated material (AAM), and its mechanical properties, durability, and microstructure were investigated. When AKA partially replaces metakaolin, the mechanical properties of AAM decrease due to its coarse particle size and low reactivity; meanwhile, adding basalt fiber (BF) can effectively improve the mechanical properties of AKA-modified AAM, especially the flexural strength. In addition, incorporating AKA also increases the water permeability of AAM. Specifically, augmenting AKA levels by 20 % and 100 % in samples without BF escalates water absorption by 6.2 % and 25.4 %, respectively, compared to AAM samples without AKA. Nevertheless, the combined application of appropriate amounts of AKA and BF is beneficial to the high-temperature resistance of AAM. For high-temperature resistance, the samples mixed with a small amount of AKA show similar residual compressive strength as plain AAMs, and adding BF effectively reduces the thermal damage. Microstructure studies also show that BF is closely combined with the AAM matrix, and adding too much AKA is not beneficial to the compactness of the microstructure of AAM. This study provides a practical approach for recycling potential biomass ash and a strategy for producing eco-friendly binders.