Experimental and simulation research on flexural mechanical properties of RPC-NC composite beams

The mechanical properties and durability of reactive powder concrete (RPC) are superior to those of normal concrete (NC). Therefore, RPC can be applied to the lower portion of beams and combined with NC to achieve a more cost-effective design. This paper focuses on the effects of reinforcement ratio, RPC height, and interface roughness on the flexural mechanical properties of RPC-NC composite beams. Six RPC-NC composite beams and two monolithic beams were tested. The failure characteristics, mechanical behavior, and bearing capacity of RPC-NC composite beams were analyzed. The results indicate that the failure process of RPC-NC composite beams can be divided into three stages, with no failure occurring along the interface. When the RPC prefabricated height ratio is in the range of 0.5–0.6, the optimal balance between the economy and safety of RPC-NC composite beams can be achieved. The reinforcement ratio and RPC height have significant effects on flexural properties of composite beams. When the interface roughness is not less than 2.632 mm, the effect of interface roughness is relatively small. Given the combined effects of RPC height and reinforcement ratio, formulas for the cracking and ultimate bending moment of RPC-NC composite beams were established by introducing the RPC tensile influence coefficient of k . The theoretical values of cracking and ultimate bending moment obtained are in good agreement with the experimental results. Additionally, the entire flexural process of RPC-NC composite beams is analyzed using the finite element software ABAQUS, and the analysis results show a good match with the experimental data. • Revelation of the flexural mechanical properties of RPC-NC composite beams. • Exhibition fine cracks at composite beams and no failure along the interface. • RPC height has significant effect on flexural properties of RPC-NC composite beam. • Formulas derivation of cracking and ultimate bending moment of RPC-NC beam. • Results of experiment, calculation and numerical simulation show a good match.