Development of an environmental Ultra-High Performance Concrete (UHPC) incorporating carbonated recycled coarse aggregate

This paper presents a new idea based on the efficient use of recycled Construction and Demolition Waste to produce advanced building materials, which focus on the development of Ultra-High Performance Concrete (UHPC) by carbonated recycled coarse aggregate (CRCA). Firstly, the accelerated carbonization is used to strengthen the recycled coarse aggregate. Secondly, the improved Andreasen&-Andersen (A&A) particle accumulation model is used to develop CRCA-UHPC with a maximum particle size of 4.75 mm. After that, the impact of the added CRCA on the performances of UHPC are evaluated, including flowability, setting time, compressive strength, volume stability, durability, microstructure, etc. The obtained results show that when the RCA is subjected to carbonation treatment, its drawbacks of physical and mechanical characteristics can be efficiently restricted, and the properties of UHPC incorporating CRCA could be improved, including compressive strength, volume stability, resistance to chloride ion penetration, microstructure and eco properties. Therefore, the CRCA-UHPC proposed in this study should be a promising sustainable new construction material, which can not only solve the environmental problems caused by construction waste and CO2 emission, but also provide an advanced building material.