Study on Mechanical Characteristics of Composite Alkali-activated Materials-stabilized Gold Tailings Under Direct Shear

Abstract

In this study, the traditional industrial waste residue and some alkaline activators were mixed to prepare a new composite alkali-activated materials (CAAMs), which was used to stabilize gold mine tailings (GMTs). Due to emissions of greenhouse gases and solid dust, alkali-activated materials have been widely used to replace Portland cement to solidify geotechnical materials to enhance their mechanical properties. Different admixture of CAAMs (i.e., 0, 3, 5, 8% ) and gold mine tailings were prepared, and the samples were cured in saturated water and under no air conditions. In order to investigate the mechanical characteristics of CAAMs-stabilized GMTs, laboratory direct shear tests were carried out on samples after curing them for 3, 7, 14 and 28 days, respectively. The test results showed that as the curing periods increased, the brittleness of the samples increased, and the stress-displacement curves for all the cured specimens changed from plateau-type to peak-type curves. The curing periods and the content of CAAMs are both beneficial for enhancing the shear strength of CAAMs-stabilized GMTs samples, but the increase rate decreased as the vertical confining pressure increased. Furthermore, the influence of CAAMs content on shear strength increment was larger than that of curing periods. An exponential growth model could be well used to describe the change of shear strength with the curing periods at different vertical stresses.