Abstract
The application of recycled aggregate concrete (RAC) has developed rapidly in recent years. But how to evaluate the residual properties of RAC after the fires is more beneficial to the further popularization and application of RAC. This paper presents the residual properties of RAC and steel reinforced recycled aggregate concrete (SRRAC) components after exposure to elevated temperature. A total of 176 specimens (120 rectangular prisms specimens, 24 SRRAC short columns and 32 SRRAC beams) were designed and tested after exposure to elevated temperature. The parameters were considered in the test, including replacement percentage of recycled coarse aggregate (0%, 30%, 50%, 70% and 100%) and exposure to different temperatures (20, 200, 400, 600 and 800 degrees centigrade). According to the test results, heat damage and residual properties of specimens were analyzed in detail, such as surface change, mass loss, bearing capacity degradation, stiffness degradation, ductility and energy dissipation of specimens under the elevated temperature. The results showed that a series of significant physical phenomena occurred on the surface of RAC and SRRAC components after exposure to elevated temperature, such as the color changed from green-grey to gray-white, chapped on the concrete surface after 400 degrees centigrade and the mass loss of concrete is less than 10%. The degradation of mechanical properties degenerated significantly with the increase of temperature, such as the strength of RAC, and compressive capacity, bending capacity, shear capacity and stiffness of SRRAC components, among that, the degradation of the strength of RAC was most obvious, up to 26%. The ductility and energy dissipation of SRRAC components were insignificant affected by the elevated temperature. Mass loss ratio, peak deformation and bearing capacity showed a slight increase trend with the increase of replacement percentage. But the stiffness showed significant fluctuation when replacement percentage was 70% to 100%. And the ductility and energy dissipation showed significant fluctuation when replacement percentage was 30% to 70%.
Highlights
Demolished concrete is used to make recycled aggregate concrete (RAC), which has the advantages of being energy-saving and environment-friendly
The results show that the flexural strength [18,19] and shear strength [20] of steel reinforced recycled aggregate concrete (SRRAC) beams are similar to those of steel reinforced concrete (SRC) beams
The results show that the residual performance of RAC after exposure to elevated temperature is optimal level when replacement percentage is 50% [26]
Summary
Demolished concrete is used to make RAC, which has the advantages of being energy-saving and environment-friendly. Recycled fine aggregate with demolished concrete has little effect on the mechanical properties of RAC, when the replacement percentage is less than 30% [10]. The results show that the residual performance of RAC after exposure to elevated temperature is optimal level when replacement percentage is 50% [26]. The increase of RAC strength can improve its impact behaviors when the temperature is lower than 500 degrees centigrade. Research on the residual properties of SRRAC components after exposure to elevated temperature is limited That it needs to be further studied. The parameters were considered in the test, like replacement percentage of recycled coarse aggregate (0%, 30%, 50%, 70% and 100%) and exposure to different temperatures (20, 200, 400, 600 and 800 degrees centigrade).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
