Application of steel fiber reinforced lightweight aggregate concrete in underground mining

Several devices are used to provide support in an underground space. Wooden prop is generally employed for the purpose of passive secondary or short-term support of the mine roadway roof and sides. The wooden prop has various known usage limitation, including low strength, deterioration of wood in humid environment, poor ductility, and generally low service life. Substitution of the wooden prop with a prop made with a more suitable material could thus yield important advantages. In this study, lightweight aggregate concrete (LWAC) is proposed to be used as a prop material. Since lightweight aggregate has a relatively low ductility, steel fibers are used in this investigation to achieve enhanced ductility levels. Five mixtures of fiber reinforced lightweight aggregate concrete were considered with different steel fiber percentages and pumice lightweight aggregates produced in Iran. The density, compressive, tensile and flexural strength as well as the toughness index of different fiber reinforced lightweight aggregate concrete materials were measured in order to assess their potential as replacement for wood in prop production. The experimental results indicated that the density of lightweight aggregate concrete is higher than wood. Since the strength and toughness of LWAC is significantly more than those of wood, the weight of a LWAC element with the same strength turns out to be 22 percent less than the wood element. Hence, wooden prop may be replaced with lightweight aggregate concrete prop to achieve improved service life and ductility while reducing the weight of the prop.