Uniaxial compressive behaviour of a FRP standing support made of mine wastes

Twenty-seven specimens were tested to investigate the uniaxial compression behaviour of an innovative standing support for underground space applications. The innovative standing support consisted of an external fibre reinforced polymer (FRP) jacket and the infill column made of cementitious grout, tailings and coal wash rejects. Effects of the FRP layers number and water to the cementitious grout (w/g) ratio were evaluated. Test results indicated that lower w/g ratios produced stronger infill columns. With FRP confinement, the standing support demonstrated strain-hardening loading characteristics with a significant improvement in both strength and ductility. The highest strength and strain of the specimens achieved was 58.4 MPa and 11.8% respectively. Compared with the unconfined specimens, the confinement with four FRP layers increased the specimen strength and associated strain up to 3.6 and 27.0 times respectively. A correlation between the compressive strength of the infill material and the ultrasonic pulse velocity was also investigated. Furthermore, a simple design-oriented model was proposed to predict the peak strength and the corresponding strain of the innovative standing support.