Development and Material Characterization of Advanced Polymer Fibre-Reinforced Shotcrete for Tunnel Applications

Abstract

The growing market for long-lasting and high performance tunnel lining systems has driven the need of novel construction materials that can survive in multi-extreme ground environment. Traditional shotcrete, which is also widely employed in tunnel support systems, is known to be brittle and is prone to cracking and its durability in aggressive environment is also questioned. In order to tackle these problems, the present work research the design of a tunnel application shotcrete, named polymer fibre reinforced shotcrete (PFRS), and its development and material testing. In this study, polymer fibres are added to shotcrete mixtures with different volume contents to improve mechanical properties, crack resistance and durability. A comprehensive set of tests is made to determine compressive strength, flexural strength, split tensile strength and toughness properties. Moreover,microstructural study is carried out to comprehend fibre–matrix interfacing and crack-bridging mechanisms. The results confirm improved ductility, post cracking behaviour and crack propagation resistance compared to ordinary shotcrete. A proper balance between workability and mechanical performance is obtained with this optimal fibre amount. The results confirm the potential improvement of polymer fibre reinforced shotcrete as an alternative for tunnel lining systems with better structural safety and long service life. The present work opens a new avenue for more comprehensive structural and field-level study on enhanced shotcrete materials.