Development of non-OPC binder using fly ash, limestone powder, gibbsite powder, and biomass ash for workability, strength, and CO capture.

Ordinary Portland Cement (OPC) is a major contributor to global CO emissions due to the energy-intensive calcination process required for its production, highlighting the critical need for alternative binder systems that can reduce or replace cement while still meeting the practical applications. The development of this alternative binder opens opportunities for researchers to design solutions for various purposes, not only reducing or replacing cement but also offering additional benefits, such as CO₂ absorption. This research explores the synergistic of a sustainable non-OPC binder system incorporating high volumes of fly ash, limestone powder, gibbsite powder, and biomass ash (BA), presenting a sustainable local alternative for construction materials. By evaluating workability, compressive strength, and CO uptake. The results show that low BA content enhances flowability, while higher BA content improves compressive strength (up to 29 MPa at 56 days) by facilitating pozzolanic reactions and the formation of carboaluminate phases. Additionally, the high alkalinity of BA enhanced CO sequestration, with the highest absorption (2.7%) observed at 15% BA content. XRD and DTA analysis confirm active pozzolanic reactions, calcium aluminate formations, and the influence of carbonation reactions. These findings highlight the potential of this non-OPC binder for practical applications in environmentally friendly construction, offering reduced reliance on cement while effectively sequestering CO.