Effect of High Temperature Curing on the Frost Resistance of Recycled Aggregate Concrete and the Physical Properties of Second-Generation Recycled Coarse Aggregate under Freeze-Thaw Cycles

With the emphasis on environmental issues, the recycling of waste concrete, even recycled concrete, has become a hot spot in the field of architecture. But the repeated recycling of waste concrete used in harsh environments is still a complex problem. This paper discusses the durability and recyclability of recycled aggregate concrete (RAC) as a prefabricated material in the harsh environment, the effect of high-temperature curing (60°C, 80°C, and 100°C) on the frost resistance of RAC and physical properties of the second generation recycled coarse aggregate (RCA2) of RAC after 300 freeze-thaw cycles were studied. The frost resistance of RAC was characterized by compressive strength, relative dynamic elastic modulus, and mass loss. As the physical properties of RCA2, the apparent density, water absorption, and crushing value were measured. And the SEM images of RAC after 300 freeze-thaw cycles were shown. The results indicated that the frost resistance of RAC cured at 80°C for 7 days was comparable to that cured in the standard condition (cured for 28 days at 20°C ± 2°C and 95% humidity), and the RAC cured at 100°C was slightly worse. However, the frost resistance of RAC cured at 60°C deteriorated seriously. The RAC cured at 80°C for 7 days is the best. Whether after the freeze-thaw cycle or not, the RCA that curd at 60°C, 80°C, and 100°C for 7 days can also meet the requirements of Grade III RCA and be used as the aggregate of non-bearing part of prefabricated concrete components. RCA2 which is cured at 80°C for 7 days had the best physical properties. © 2023, Tech Science Press. All rights reserved.