Rice Straw Ash as a Sustainable Cementitious Binder: Investigations into Pretreatment and Performance

As part of its sustainable development goals, India has been promoting biomass-to-energy projects to convert agricultural waste into renewable energy and reduce pollution from the open burning of residues. Rice straw-fuelled power plants in northern India generate large quantities of rice straw ash (RSA) as a by-product. RSA has probable use as a supplementary cementitious material (SCM), but there is limited literature. This study aimed to characterise RSA from three different power plants and investigate its feasibility as an SCM. Analysis revealed that RSA contains silica but has a larger proportion of Potassium Chloride (KCl) contributing to a low strength activity index (S.A.I). A washing pretreatment process demonstrated high efficiency in removing the salts and significantly improved its S.A.I indicating excellent pozzolanic activity and potential for utilization as an SCM. Moreover, the wastewater collected from the washing process yielded crystalline KCl, which can be recycled.