LAUSR

Abstract The cement and concrete production industries are widely acknowledged as one of the major contributors of carbon dioxide in the modern world. Extensive research have been undertaken over the years to enhance the sustainability and resilience aspects of these industries, as well as to neutralize their carbon footprint. This study aims to utilize palm oil fuel ash (POFA) and rice husk ash (RHA) to produce nano cementitious additives (NCA) for carbon-neutral cement (CNC). The performance of NCA was evaluated in ordinary Portland cement (OPC) concrete by replacing the OPC at dosages of 0.5% and 1.0%. CNC with 100% supplementary materials was activated with 2.5 M NaOH concentration. The activated CNC was used to replace OPC from 0% to 100% in concrete, and their workability, pozzolanic reactivity, and early-age and long-term compressive strength performances were analyzed. Subsequently, micro- and nano-scaled fibers were introduced into the mix with 100% CNC to enhance the flexural and tensile characteristics of the composite. The findings indicated that low-dosage of NCA (0.5%) resulted in increased early-age strength, whereas NCA at 1.0% enhanced the early-age and ultimate strength of the concrete. The inclusion of micro- and nano-scaled fibers contributed in enhancing the flexural characteristics of the concrete matrix. It can be deduced that NCA is feasible to function as strength enhancer for OPC or as an activator to produce CNC, thus offering a novel sustainable construction material and contributing towards greener construction.