CCU Structure · A new CCU composite structure with a novel demountable connection towards CO2 sequestration and material recyclability.

Carbon Capture and Utilization (CCU) is receiving increasing interest due to the continuously increasing CO2 emission, where one pathway is to mineralize carbon in concrete building material. Compared with Portland cement, reactive magnesia cement (RMC) has the potential advantage of higher CO2 sequestration during early age curing and its service life. Still, the inadequate carbonation depth limits its application. Another approach to reducing carbon emissions is recycling and reusing components in construction. The key to realizing component reuse and concrete material recycling is the proper demountable connection. However, the sudden slippage and labor-consuming problems of bolts were reported and might hinder the popularity of reusable structures.Therefore, this project will introduce hollow natural fibers (HNFs) with large lumens to enhance CO2 penetration and overcome the carbonation depth limitation. The participants will co-develop a mix design of HNF-reinforced RMC-based concrete that achieves a compressive strength of 50 MPa and a one-way carbonation depth of 60 mm. Besides, a novel demountable bolt-wedge system for dowel-based connectors will be proposed to realize excellent mechanical behavior and efficient construction of CCU composite structures. The shear behavior of the demountable connectors with the bolt-wedge system will be investigated by conducting push-out tests and finite element modelling.For the scientific community, the mix design will provide a solution for CCU structures, and the bolt-wedge system may initiate new research on prefabricated and reusable structures. Regarding societal and economic impacts, the proposed CCU composite structure could reduce emissions by CO2 sequestration and lower the net costs of reducing emissions due to the enormous scale of infrastructure. Reusing structural elements after their first design can decrease construction time and material costs. This project is in line with the ""European Green Deal"" goals.""