Study on enhancing recycled aggregate concrete using high belite sulfoaluminate cement

This paper aims to improve the interfacial defects between aggregate and mortar by wrapping reinforced recycled aggregates (RCA) using high belite sulfoaluminate cement (HBSAC) slurry. Static and dynamic mechanical tests were performed on HC-1.1, HC-0.9, and HC-0.7 concretes prepared by HBSAC wrapped paste reinforced RCA based on water-cement ratios of 1.1, 0.9, and 0.7. Using low-field nuclear magnetic resonance (NMR), microhardness , and scanning electron microscopy (SEM) tests were conducted to reveal the mechanism by which wrapped RCA improves the properties of recycled concrete. The results showed that the HBSAC slurry reinforcement improved the mechanical properties of RAC , the static mechanical properties increased by 4.5 %–14.3 %, and the dynamic mechanical properties increased by 5.7 %–27.5 %, but there was a difference in the effect of the water-cement ratio of the HBSAC wrapped slurry on the improvement of the mechanical properties of RAC. Microscopic tests showed that the less-harmful pores, harmful pores, and highly-harmful pores of reinforced RAC were reduced. The interface between HBSAC and OPC had good contact and dense connection, and the hardness of the reinforced interface was increased by 8.6 %–11.3 %. • Based on the water-cement ratios of HBSAC slurry, the static and dynamic mechanical properties of reinforced RAC were investigated. • The reinforcement mechanism of the coating slurry was analyzed by combining nuclear magnetic resonance (NMR), microhardness , and scanning electron microscopy (SEM) tests.