Synergetic effect of CO2 curing and bottom ash with low Ca on the enhancement of carbonation behavior and mechanical performance

Abstract

This study investigated ordinary Portland cement substituted with ground bottom ash (BAOPC) under various conditions of BA contents and CO2 curing. In samples without CO2 curing, the strength development along with degree of hydration were limited as expected. A higher BA content led to decreased compressive strength, indicating an inferior pozzolanic reaction of BA. Meanwhile, in the CO2-cured samples, a positive correlation between calcium carbonate (CC) content and compressive strength was confirmed, suggesting that CC is a key factor influencing strength development as a result of external CO2 supply. In particular, a higher amount of CC was present in the BAOPC composite with 20% BA substitution compared to the sample with 100% OPC, and substantial mechanical bonding between CC crystals was also confirmed. This study revealed that the combination of BA with limited Ca content and CO2 curing holds promise for developing eco-friendly formulations with enhanced mechanical properties and CO2 utilization.