Behavior of low-carbon cementitious composites incorporating wood ash and basalt powder for enhanced strength and durability

This research explores the potential of wood ash and basalt powder in developing sustainable, low-carbon cementitious composites. The study evaluates the effectiveness of wood ash as a supplementary cementitious material and basalt powder as a sand substitute in mortar and concrete mixtures. Wood ash was incorporated as a cement replacement, up to 30%, and basalt powder was used to replace the sand by up to 100%. A series of experimental tests were carried out to assess fresh properties, mechanical performance, microstructural characteristics, and durability, including freeze-thaw resistance, chloride penetration, sorptivity, and elevated temperature exposure. Results indicate that increasing wood ash content was detrimental, whereas increasing basalt powder was reported to positively impact the mortar and concrete properties. At optimal replacement levels, wood ash enhances long-term strength due to its pozzolanic activity, while basalt powder improves particle packing, leading to denser concrete. The optimal replacement ratio of wood ash was recorded as 10% in both mortar and concrete mixes. In the case of basalt powder, the optimal replacement was concluded as 100% and 50% in mortars and concrete, respectively. The strength was found to be increased by 60.81% compared to the reference sample after 28 days at 100% substitution of basalt powder as fine aggregate. The strength of mortar and concrete mixes was improved by 25% and 18.2% at 10% wood ash content in addition to basalt powder as sand substitute after 28 days. However, the addition of these materials resulted in reduced workability, requiring appropriate admixtures for practical applications. Besides, incorporating wood ash and basalt powder in concrete production can reduce environmental impact by utilizing industrial waste, lowering carbon emissions, and minimizing the depletion of natural resources. These findings provide valuable insights for researchers and industry professionals seeking sustainable alternatives in modern construction.