Mode I fracture behavior of metakaolin-based geopolymers made of mine tailings

Asadizadeh M.; Clements C.; Hedayat A.; Tunstall L.; Gelber Bolanos Sosa H.; Tupa N.; Yanqui Morales I. · 58th US Rock Mechanics / Geomechanics Symposium 2024, ARMA 2024 (2024) · DOI: 10.56952/arma-2024-0571

Resumen

Converting mine tailings rich in aluminum oxide and silicon dioxide into a geopolymer using an alkali activator offers an eco-friendly solution for mitigating the environmental impact of mine tailings and reducing associated disposal costs. In the realm of construction materials, thorough investigations into the mechanical properties of geopolymers are essential to gain a better understanding of their performance when subjected to varying loading conditions. This includes a comprehensive understanding of their fracture behavior when subjected to mode I loading, a critical aspect for their effective deployment in mode I loading scenarios. In this study, a semi-circular bend (SCB) test fixture was employed to analyze mode I fracture behavior of geopolymer specimens, a research topic that has been largely unexplored. Different geopolymer compositions comprising mine tailings (50% wt.), low-reactive slag (50% wt.), and varying metakaolin percentages (10% wt. and 20% wt. of total solid) were prepared by mixing the solids with a 10 M NaOH solution with a liquid/solid ratio of 20%. Using a cylindrical mold, we cast geopolymer specimens, which were then subjected to curing at slightly elevated temperatures over an eleven-day period. The semicircular specimens were prepared by cutting the cured samples into notched disks, and a series of three-point bending tests were conducted. We delved into the examination of mode I fracture toughness and its sensitivity to the percentage of metakaolin through the utilization of digital image correlation techniques. Our research showed that by increasing metakaolin from 10% to 20%, the crack tip opening displacement (CTOD) increased from 19.29 μm to 37.63 μm; however, the fracture process zone (FPZ) decreased from 2.40 mm to 1.93 mm.. Copyright 2024 ARMA, American Rock Mechanics Association.

Instituciones: Universidad Nacional de San Agustín de Arequipa