Mechanical response of RPC200 and RPC250 under elevated temperature: An experimental investigation

Reactive Powder Concrete (RPC) offers superior mechanical properties and lower carbon emissions than Normal Concrete (NC) and High-Strength Concrete (HSC). In previous studies, there has been no research on the mechanical evolution law of RPC with compressive strength exceeding 200 MPa at high temperatures. In this paper, RPC200 and RPC250 mixes with target compressive strengths of 200 MPa and 250 MPa were successfully developed. The high-temperature damage characteristics of RPC were systematically investigated, and uniaxial compressive stress–strain constitutive models for RPC200 and RPC250 under elevated temperatures were established. The results showed that the combined curing regime leads to ultra-high-strength RPC and significantly enhances its resistance to fire-induced spalling, even without PP fibers. When exposed to temperatures above 300°C, the degradation in compressive strength of RPC200 and RPC250 is markedly lower than that observed for NC and HSC. Particularly, at 800 °C, the cube compressive strengths of RPC200 and RPC250 retained 44.4 % and 50.6 % of their ambient-temperature strengths, respectively, while their axial compressive strengths remained at 32.0 % and 28.8 %. ABAQUS analysis has proved that the fire resistance limits of RPC200 and RPC250 columns are 172.1 min and 193.8 min respectively, and their fire resistance performance is much higher than that of NC columns and RPC150 columns. Overall, RPC200 and RPC250 have significant advantages at high temperatures, which is conducive to promoting the application of RPC in nuclear power, large-span buildings and other fields.