Micromechanical analysis of fiber-reinforced reactive powder concrete with imperfect interface after high temperatures

In this study, the mechanical properties and mesoscopic failure mechanisms of steel fiber-reinforced reactive powder concrete (SRPC) after different temperature conditions were investigated using a meso-mechanical method. The impact of the imperfect interface between steel fibers and the reactive powder concrete (RPC) matrix on the overall performance was analyzed. SRPC is modeled as a three-phase composite comprising the RPC matrix with pores, steel fibers, and interfacial transition zone (ITZ). A multi-scale homogenization method was developed by integrating the Mori-Tanaka (M-T) scheme with an improved meso-mechanical model that accounts for the imperfect interface and the random distribution of fibers. Experimental and numerical simulations were conducted to examine the variations in SRPC compressive strength, elastic modulus, and meso-structure over a temperature range from room temperature (RT) to 800 °C. Microstructural analysis indicated that the imperfect bonding between steel fibers and the RPC matrix has a considerable effect on the mechanical properties of SRPC. Additionally, a parametric analysis was conducted on ITZ with varying thicknesses and different elastic moduli. The results of model calculations were compared with experimental determination value, demonstrating the accuracy and effectiveness of the proposed method.