Life Cycle Assessment of Cementitious Composites: An Investigation on CO2-Cured Concrete

Cementitious composite, which is widely used in the construction of infrastructure, generates a considerable quantity of carbon emissions throughout its lifecycle, thereby resulting in a profound effect on the environment. In order to promote low-carbon development of the cement industry, it is essential to employ a life cycle assessment methodology from a perspective of sustainable development to conduct a quantitative evaluation of the impact of cementitious composite, for example, environmental, economic, and social benefits. Due to the fact that CO2-cured concrete has the potential to facilitate high-value utilization and sequestration of CO2, CO2-cured concrete was used as an example to investigate the environmental impact generated during its life cycle. Based on an analysis of existing literature and experimental investigations, a database for CO2-cured concrete was established. Then, the life cycle carbon emissions of the CO2-cured concrete were calculated, and the important processes for the carbon footprint were subsequently analyzed. In addition, Monte Carlo simulation method was employed to investigate the impact of carbon emission coefficients of the raw materials on the net environmental benefit calculation results. The results demonstrated that carbon emissions from production process of cement and the curing process of concrete are key factors influencing the environmental benefits of CO2-cured concrete. Moreover, the impact of the curing regime on the life cycle net environmental benefits was analyzed. It was found that an increase in the CO2 curing period or gas pressure can enhance the amount of CO2 captured by concrete. However, these processes also lead to an increase in the energy consumption of CO2 curing equipment, resulting in excessive carbon emissions during the production process of CO2-cured concrete. An excessive CO2 curing period, high pressure, and the reduction in the mechanical properties of concrete can lead to a negative net environmental benefits for CO2-cured concrete. Accordingly, the findings of this study suggested that atmospheric pressure CO2 curing for a period of less than 6 hours represents an optimal regime.