▎ 摘　　要

The brittle nature of reactive powder concrete (RPC) and existence of inertial stress (at high strain rates) made it suffer tensile failure and seriously affected the safety of concrete structure. Graphene with low density and small size easily dispersed in concrete matrix, while its high stiffness and diameter-to-thickness ratio could effectively offset the inertia stress, contributing to improve the energy absorption of the concrete. In this paper, the RPC was nano-modified by combining the characteristics of graphene and concrete. The mechanical behaviors of RPC under different strain rates were systematically studied, and the effects of graphene on mechanical performance of RPC were analyzed. Finally, the reinforcing mechanisms of graphene on RPC were understood, and the dynamic compression constitutive of RPC was established, which provided a theoretical basis for understanding the dynamic mechanical properties and behaviors of this concrete material for the first time. Experimental results showed that under quasi-static loads, the incorporation of graphene significantly enhanced the compressive toughness of RPC. Under the high rate dynamic loads (strain rate of 200-800/s), the dynamic compressive strength, peak strain and ultimate strain of graphene-reinforced RPC were increased by 59.1 MPa/63.9%, 4300 mu epsilon/66.0% and 12150 mu epsilon/32.7%, respectively. Additionally, the impact toughness of RPC was increased by 117%. The reinforcing mechanisms of graphene on RPC were mainly attributed to their nucleation and bridging effect. Furthermore, the interlaminar slip and structural fracture of graphene further absorbed strain energy released by cracking and therefore improved the mechanical properties of the RPC.