Amine-based additives to enhance the carbonation rate of cement-based materials: A pathway to CO2 neutrality

The cement industry is responsible for about 8 % of global CO 2 emissions and must achieve carbon neutrality by 2050 to meet international climate targets. Although cement-based materials can sequester up to 20 % of process-related CO 2 emissions through natural carbonation, this process is slow and offers limited short-term mitigation. This paper reviews the potential of amine-based additives to accelerate carbonation and enhance the CO 2 sequestration capacity of cement-based materials. Amine-based additives, such as ethanolamine (MEA) and triethanolamine (TEA), have shown the ability to enhance CO 2 capture, while also improving the durability of cementitious materials by refining their microstructure. These dual benefits suggest that amine-modified materials hold great promise for advancing carbon-neutral construction practices. This review, for the first time, is connecting the concept of CO 2 capture using amine-based additives and the carbonation rate of cementitious materials. It discusses the process of CO 2 absorption by amines, the effects of amine-based additives on the microstructure and chemistry of cement, and the mechanisms by which they enhance CO 2 capture. Additionally, the review uniquely analyzes recent advances in three amine-based strategies, namely, aqueous amine solutions, CO 2 -rich amines, and solid amine-functionalized sorbents, for enhancing CO 2 sequestration in cementitious materials. It highlights potential benefits on both carbonation and mechanical strength, while noting gaps in amine dosage, sulfate resistance, and long-term durability.