Abstract
Green recycled aggregate concrete (RAC) with high strength and low shrinkage is prepared based on recycled coarse aggregate produced by the particle-shaping and aggregate-strengthening method and green low-carbon new cement. This not only effectively alleviates the shortage of natural resources, but also improves the performance of recycled aggregate concrete, which is of great significance for multi-channel resource utilization of construction waste. In this study, three kinds of recycled coarse aggregates (RCA), including simple crushing recycled coarse aggregate (JD-RCA), one-time particle-shaping recycled coarse aggregate (KL-RCA) and two-time particle-shaping recycled coarse aggregate (EKL-RCA), were prepared from the preparation technology of recycled aggregate, and high belite sulphoaluminate cement with excellent performance was used. The effects of aggregate quality, aggregate replacement ratio, and cementitious material content on mechanical properties and shrinkage properties of green recycled aggregate concrete were studied in comparison with ordinary Portland cement-based recycled aggregate concrete. The testing results show that the particle-shaping method can effectively improve the aggregate quality. The compressive strength and dry shrinkage performance of recycled aggregate concrete made of particle-shaped aggregate are only a little different from those of natural aggregate concrete, and even the performance of recycled aggregate is better than that of natural aggregate concrete under the condition of a low replacement ratio of recycled aggregate. In addition, high belite sulphoaluminate cement-based recycled aggregate concrete (HBRAC) not only has early strength and rapid hardening, but also has excellent drying shrinkage resistance, and its shrinkage rate can be reduced to more than 75% compared with ordinary Portland cement-based recycled aggregate concrete (OPRAC).
Highlights
In recent years, the rapid development of the global economy has led to the rapid rise of the construction industry, but its rapid development inevitably faces many problems such as construction waste pollution and over-exploitation of natural aggregate
How to reuse recycled coarse aggregate (RCA) in concrete is an important subject in the research of recycled aggregate concrete (RAC), which promotes the rapid development of reinforced preparation technology of RCA
High-quality recycled coarse aggregate was prepared by recycled aggregate preparation technology and used in recycled aggregate concrete together with high belite sulphoaluminate cement with excellent performance
Summary
The rapid development of the global economy has led to the rapid rise of the construction industry, but its rapid development inevitably faces many problems such as construction waste pollution and over-exploitation of natural aggregate. How to reuse recycled coarse aggregate (RCA) in concrete is an important subject in the research of recycled aggregate concrete (RAC), which promotes the rapid development of reinforced preparation technology of RCA. This technology can improve the inferior properties of RCA, such as roughness, porosity, high water absorption, and high crushing index. It treats construction waste after a series of processes and re-use it as building materials [11,12,13,14,15]. The particle-shaping method used in this paper is a new technology that can effectively grind the old mortar and cement paste attached to the surface of RCA by using the repeated impact and mutual friction between RCAs under the high-speed movement of line speed (the speed of the fixed axis of the vertical rotating impeller in circular motion at any point of the recycled aggregate) ≥80 m/s and can effectively strengthen RCA [24]
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