Carbon sequestration, performance optimization and environmental impact assessment of functional materials in cementitious composites

This paper reviews the mechanisms of carbon sequestration, methods for testing carbon sequestration capacity, and the performance of functional materials, including wollastonite, titanium dioxide nanoparticles (Nano-TiO2), graphene oxide (GO), biochar, and cellulose fibers (CS), as well as their performance in cement-based materials. A system boundary model has been developed to facilitate a comprehensive analysis of the environmental impact associated with preparing these materials as concretes. It is demonstrated that wollastonite reacts with atmospheric carbon dioxide (CO2) to form carbonate minerals, contributing to carbon sequestration. Nano-TiO2 and GO absorb and transform CO2 through light-excited charge carriers to generate redox reactions and oxide functional groups on their surfaces and edges, respectively. Biochar achieves carbon sequestration through physical and chemical stability, while the carbon sequestration mechanism in cellulose fibers is related to their structural properties as plant materials. In cement-based materials, wollastonite significantly enhances mechanical properties by filling pores and bridging microcracks. Nano-TiO2 and GO enhance mechanical properties by providing nucleation sites and template effects, among other mechanisms. An appropriate amount of biochar improves densification and strength, while cellulose fibers facilitate the cement hydration process, thus enhancing mechanical properties. Additionally, Life Cycle Assessment (LCA) analyses demonstrate that wollastonite and cellulose fibers offer sustainable environmental benefits in producing low-carbon concrete due to their low Global Warming Potential (GWP) and minimal negative impacts on the environment and human health. This review emphasizes the pivotal role of these functional construction materials in mitigating climate change.