Graphite Tailings’ Effects on Mechanical and Physical Properties of Eco-Efficient Steel Fiber-Reinforced Concrete

Abstract

As impacted by environmental concerns and the demand for high-strength concrete, novel ideas of the development of eco-efficient, steel fiber-reinforced concrete have been proposed. In this study, the aim is to develop a type of eco-efficient steel fiber-reinforced concrete with graphite tailings and steel fiber. Steel fibers act as a type of concrete toughening material, and graphite tailings serve as a partially alternated aggregate to sand. Mechanical properties exhibited by the concrete are assessed based on different volume fractions of graphite tailings (i.e., 0%, 10% and 20%). The concrete mixture proportion is determined in accordance with the theory of particle densely packing, and the concrete mechanical properties are more specifically studied by performing compressive and flexural tests. As indicated by the results, the maximal mixed bulk density of graphite tailings at different grades is greater than that of sand, so concrete with graphite tailings exhibits higher compressive strength. For the content of graphite tailings, the addition of graphite tailings impacts the interfacial adhesion between aggregates and cementing matrix, thereby inhibiting bifurcation and convergence of cracks. However, excessive mixing of graphite tailings would decrease the specimen’s effective water-to-binder ratio (W/B), thereby adversely affecting the internal structure of the concrete. The amount of graphite tailings impacts the distribution of steel fibers at the concrete interface, which could be the most conducive to the distribution of steel fibers under the graphite tailings’ content of 10%. This study demonstrates that graphite tailings and steel fibers are feasible to prepare eco-efficient, steel fiber-reinforced concrete.