Feasibility analysis of treating aeolian sand and recycled mixed powder as environmentally friendly materials in the ultra-high-performance concrete

This paper addresses the performance and environmental impact evaluation of a developed UHPC with recycled mixed powder (RMP) and aeolian sand (AS). The RMP is obtained from the crushing and grinding of waste concrete blocks and clay bricks. The RMP and AS are used instead of cement and river sand during the UHPC's production. The macroperformance, hydration kinetics, microstructure development, and environmental impact of the newly produced UHPC are evaluated. The experimental results reveal that the effect and mechanism of RMP on the fluidity of UHPC are different from that of AS. The RMP and AS show a specific synergistic effect. The RMP can promote the initial hydration of the mixture but restricts its cumulative heat. The AS acts as a nucleation site to promote the secondary hydration reaction involving RMP. The ecological assessment demonstrates that the developed UHPC incorporating RMP and AS can reduce the burden on the environment.