CO emission assessment of lightweight aggregate concrete using artificial lightweight and bottom ash particles

This paper proposes empirical models to straightforwardly assess the CO emissions of artificial lightweight aggregate concrete (ALWC) and bottom ash aggregate concrete (BAAC). The system boundary identified for the assessment was from the cradle to pre-construction, considering component materials, production, and transport of concrete. The CO emission was empirically formulated as a function of the unit binder content of concrete based on the analysis of a database, which includes 413 and 90 datasets for ALWC and BAAC, respectively. In addition, after applying ALWC and BAAC to concrete structures, their CO emissions are compared with those of normal-weight concrete (NWC) structures considering the reduction in the cross-sectional area of members resulting from the lower self-weight of concrete. In this assessment, the concrete used for all structural members is assumed to have been produced using ordinary Portland cement (OPC), featuring a 24 MPa compressive strength. Compared with the evaluated total CO emissions of the NWC structures, the ALWC and BAAC structures exhibited 36% and 24% higher CO emissions, respectively. This is because the CO emission of concrete is considerably dependent on the OPC content but marginally affected by the type of aggregate used.