Exploring sustainable alternatives: quarry dust and sugar cane bagasse ash in sodium and potassium-based alkali-activated binders for enhanced mechanical and durability properties

The increased use of sugarcane bagasse in electricity production has led to a significant rise in the dumping of sugarcane bagasse ash (SCBA). To study the efficiency of SCBA as a supplementary material in the production of alkali-activated binders (AABs), which consist of quarry dust and crushed sand as fine aggregates, the present study investigates the influence of different activators, namely NaOH-Na2SiO3 and KOH-K2SiO3, and the effect of curing type (ambient and heat curing) on the mechanical and durability properties of quarry dust-SCBA incorporated AAB. Various tests, including compressive strength, water absorption, sorptivity, and sulphate resistance, along with X-ray diffraction and scanning electron microscopy were conducted for AAB characterization. The results revealed that the addition of 20% quarry dust as an alternative to crushed sand in AAB is found to be optimum. The ambient-cured SCBA-blended AAB specimens demonstrated superior performance compared to their heat-cured counterparts. The Na-based SCBA blended AABs outperformed K-based AABs in resisting compressive strength reduction. The compressive strength of 28 days ambient cured Na-based and K-based AABs were found to be 47.8 and 32.4 MPa, respectively. Microstructural analysis revealed that the main hydration products in Na-based AAB are C-A-S-H, C-S-H, and N-A-S-H, while in K-based AAB, the main hydration products were found to be C-A-S-H, C-S-H, and K-A-S-H, respectively. The AAB mixtures consisting 10% SCBA found with superior performance compared to other SCBA blended AABs. However, excessive SCBA usage weakened the microstructure in both Na-based and K-based AABs. The findings demonstrate the potential for utilizing waste materials, such as SCBA and quarry dust, in the development of eco-friendly and high-performance alkali-activated binders, contributing to the reduction of environmental impact caused by the construction industry.