Enhancing CO2 Sequestration in Beta Dicalcium Silicate (β-C2S) with Polyacrylic Acid Addition and Improving Performance of Carbonated Composites

In this study, the effects of polyacrylic acid (PAA) with different molecular weights (MW 2000, MW 5000, and MW 240,000) and dosages (0.5%, 1%, and 2.5%) on the carbonation of beta-C2S binders were thoroughly explored. The findings offer critical insights into the influence of different molecular weights and dosages of PAA on the carbonation rate, calcium carbonate (CaCO3) formation, crystal polymorph alteration, microstructure, and mechanical strength of the final composite. The 1% dosage of MW 5000 and MW 240,000 exhibited exceptional performance in reducing porosity and enhancing the mechanical strength of the carbonated composite. At this dosage, the addition of PAA accelerates the carbonate precipitation rates. The effects of PAA became more pronounced with increasing molecular weight. The addition of 1% PAA can increase the CO2 sequestration and compressive strength of the composites by up to 120% and 106%, respectively. Furthermore, the study demonstrated that PAA remains equally effective at an elevated temperature (50 degrees C) in CO2 mineralization. This research underscores the significant potential of PAA, specifically at MW 5000 and MW 240,000, as a versatile additive for optimizing CO2 sequestration in construction materials.