Exploring microstructure and mechanical features of coupled cementitious tail-sand concrete by partial replacement of tungsten tailings

Abstract

Tailings storage is not only harmful to the environment, but also poses a great challenge to mine safety production. We consider whether coarse-grained tailings can replace standard sand in concrete to rationalize tailings’ valorization/consumption. Hence, this paper aims practicability of employing tungsten tailings to prepare shotcrete for roadway support and to explore the impact of tailings replacement (TR) rate on strength features and fine structural characteristics of coupled cemented tailings-sand concrete (CCTSC). The tailings weight replacement rate was set at 0 %-100 % with a gradient interval of 20 % in order to carry out the macro-mechanical strength and micro-mechanisms of action studies of CCTSC. Results illustrate that uniaxial compressive strength (UCS) of CCTSCs takes a linear distribution link with tailings’ replacement rate. When TR is 0 % and 100 %, the corresponding UCS of CCTSC is 4.86 MPa and 9.63 MPa, respectively, representing an increase of 98.1 %. A mixture of tensile and tensile-shear damage mainly characterizes the damage modes of CCTSC. The hydration materials of CCTSC are ettringite (AFt) and calcium silicate hydrate (CSH) gel. Hydration products gradually transitioned from Aft to CSH with increasing TR. The conclusions of the present investigation will afford data support for preparation of shotcrete support constituents for tungsten mine tailings, and its practical implementation will also have a major impact on subsequent use of tailings resources as well as low-cost green and smart mining of underground mines.