The effect of silane surface treatment on the mechanical properties of UHPFRC

Abstract Ultra-high performance fiber reinforced concrete (UHPFRC) is a new kind of cement-based composite material with high mechanical properties and excellent durability. However, the poor bonding properties between fiber and matrix in UHPFRC give rise to a weak fiber reinforcement effect. Therein, the surface of steel fiber was treated with γ-aminopropyl triethoxy silane to improve the interfacial bonding property of steel fiber. Optimal treatment of steel fibers with a silane coupling agent was determined through an orthogonal experiment. The mechanical properties, bending toughness, and energy absorption capacity of UHPFRC are investigated. The study found that bending toughness and energy absorption capacity of UHPFRC are increased by 47.6% and 78.0% with 2 vol% of treated steel fibers. The interface microstructure of steel fibers and matrix was characterized using advanced techniques, such as Fourier transforms infrared spectroscopy (FT-IR), X-ray spectroscopy (EDS), and electron microscopy (SEM). The mechanism of fiber treatment improving the interface bonding performance was revealed. This work provides a feasible method for the combination of reinforced steel fibers and the UHPFRC matrix.