The novel standing support system was recently developed at the University of Wollongong. The outer tube of this standing support is made of fiber-reinforced polymer (FRP) composite, while the infilled material is made of coal reject concrete. With the use of the high strength-to-weight ratio FRP composite, both the strength and ductility of infill potentially enhanced. Importantly, by using the coal reject concrete as infill material, a significant amount of coal reject will be used in eliminating the side effect of mining on the environment. To verify these expected advantages of this novel standing support, a series of compression tests were conducted, the test variables of which included the thickness of FRP composites as well as the volume replacement ratio of natural aggregates in coal reject concrete. Test results show that both the strength and deformation capacity of coal reject concrete have been significantly enhanced with the increase of FRP thickness, providing the possibility to generate a strain hardening standing support from the design aspects. The further research on this novel hybrid standing support is discussed as well.
A large amount of secondary standing supports have been developed and applied into practical applications for underground mines during the past decades (Barczak and Tadolini, 2005, Barczak, 2003, Zhao, 2019). These secondary standing supports include the Propsetter® system (Brown, 2018), pumpable standing support (Batchler, 2017), concrete crib (Mason, 1982), the Can® support (Tarrant, 2005) and so on. Among them, the Can® support, consisting of inner concrete and outer steel container, is generally believed to be one of the most stable product not only because of its large deformation capacity but also due to its strong ability in maintaining its integrity in critical underground environments such as the high stress for deep mining. As a result, the Can® support system has attracted much attention and been accepted by more and more coal operators.