Bonding performance and construction parameters of low-rebound shotcrete

Abstract

Shotcrete has the advantages of short setting time, high early strength, simple process and flexible operation methods. It is mainly used as temporary support in domestic highway tunnels. This study investigates the development of low-rebound shotcrete for tunnel construction by adding silica fume and fly ash into the mixture. Sandstone and limestone were employed to simulate the surrounding rock. The workability and mechanical properties of the shotcrete were evaluated based on slump tests, rebound rates, compressive strength measurements, and bonding strength tests between the surrounding rock and the shotcrete. Furthermore, the research investigated construction techniques, with an emphasis on spraying distance, shrinkage angle, and wind pressure, and optimized these parameters for practical engineering uses. The outcomes demonstrate that the addition of silica fume enhances the mechanical properties of the shotcrete and reduces rebound. It was discovered that optimal spraying distance was between 1.2 m and 1.5 m, with the optimal wind pressure at 0.5 m, and the ideal shrinkage angle at 6°.Research on low rebound shotcrete is of great significance for improving construction quality, construction efficiency and engineering structural performance, and also meets the requirements of sustainable development.