Understanding the mode I fracture behaviors of the geopolymer made by alkaline activation of gold mine tailings

Zhang N.; Hedayat A.; Khan A.; Garg P.; Sosa B.; Gelber H. · 55th U.S. Rock Mechanics / Geomechanics Symposium 2021 (2021)

Resumen

To sustainably reuse the mine tailings and reduce the economic costs for storage and handling, Mine tailings that are rich in aluminum oxide and silicone dioxide can be used to create geopolymer via the alkaline activation. Geopolymers like any other construction materials needs to be evaluated for their mechanical response when subjected to external loads. The understanding of fracture behaviors of Mine tailings -based geopolymer is critically important for further re-use and application. However, the fracture behavior of geopolymer are largely unexplored. In this paper, the mode I fracture tests, commonly used in geomechanics field, have been evaluated for adoption for testing of geopolymers by using three-point bending instrument considering various influential parameters, such as the notch depth. Geopolymer specimens were cast into cylindrical molds by mixing tailings with 10M NaOH solution with water/tailings ratio of 22% and cured with a slightly elevated temperature at 72±2℃, for seven days. Thereafter, the cylindrical specimens were cut into semi-circular specimens and a series of semi-circular bending tests were performed. The mode I fracture toughness, KIC, of the geopolymer was obtained and the sensitivity of the results to the notch depth was evaluated. In addition, the strain behavior of the semi-circular specimens was investigated through the digital image correlation technique. Finally, the fracture process zone and crack tip opening displacement of the geopolymer were measured by the digital image correlation analysis.

Instituciones: Universidad Nacional de San Agustín de Arequipa