Novel carbonation curing of cementitious materials using different amine absorbents

Carbonation curing offers a promising solution for improving the physical and mechanical properties of cement-based materials while reducing their carbon footprint. However, challenges such as limited CO₂ diffusion within cement matrices hinder the full potential of this method. To overcome these limitations, this study introduced a novel approach using pre-carbonated amine solutions as CO₂ absorbents. Three different amines including monoethanolamine (MEA), diethanolamine (DEA), and piperazine (PZ) were evaluated at the concentrations of 0.5 %, 5 %, and 15 % as mixing solution and at 30 % as curing solution. The study assessed CO₂ sequestration potential using thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR), and mechanical and physical properties using compressive strength tests, water absorption, and dry density measurements. The results demonstrated that carbonated solutions as mixing agents significantly enhanced carbonation, with MEA and DEA outperforming PZ. In terms of mechanical properties, amine solutions at concentrations of 0.5 % and 5 % as mixing agents maintained compressive strength, while higher concentrations caused strength reduction due to the retardation effects of amines. This study identified carbonated MEA and DEA solutions at 5 % concentration as optimal mixing agents, achieving significant improvement in CO₂ sequestration, while reducing water absorption and maintaining mechanical properties. FTIR and TGA identified calcite as the primary polymorph of calcium carbonate in the carbonated pastes with amines. In contrast, amine solutions as curing solutions showed limited potential for both carbonation and strength improvement. These findings provide a pathway for developing more efficient carbonation curing methods.