Use of glass waste in the production of metakaolin-based geopolymer submitted to room temperature and thermal curing

Abstract

Metakaolinis the principal raw material utilized in the synthesis of geopolymers, although its ratio of silica and alumina contents is not ideal. Normally, the SiO2 content is adjusted with the use of silicates present in the activating solution. An eco-efficient alternative would be the use of glass waste as an additional source of silica.This work evaluates the efficiency of the alkaline activation of metakaolin, using potassium hydroxide and silicate, with and without the substitution of 12.5% of metakaolin by microparticles of glass. The efficiency of the alkaline activation was evaluated by X ray diffractometry, spectroscopy in the infrared region with the Fourier transform, nuclear magnetic resonance spectroscopy of 27Al and 29Si, specific mass and compressive strength. The results indicate the occurrence of geopolymerization with and without the use of glass waste. It was observed that the substitution of 12.5% favors the mechanical performance of the compounds at 28 days, with increases by 37% and 47% in the mechanical strength of the material with thermal curing and ambient temperature curing, respectively.

Properties of Geopolymers Based on Metakaolin and Soda-Lime Waste Glass

“…The parameters of SiO 2 /Al 2 O 3 , Na 2 O/Al 2 O 3 and Na 2 O/SiO 2 are important when designing geopolymers. Geopolymers with a polysialate-syloxo structure are believed to have a higher strength and therefore, a molar ratio of SiO 2 /Al 2 O 3 ranging from 3.3 to 4.5 is optimal [39,63,64]. In turn, the alkali content affects the solubility of aluminosilicates and the stabilization of aluminium cations in tetrahedral coordination.…”

“…When analysing the results of research concerning the possibility of using waste glass, the largest disadvantage of glass in building materials made from commonly used cement is the alkali content. This is why the use of glass cullet for geopolymers has been proposed in scientific research [35][36][37][38][39][40][41][42][43][44]. Geopolymers are considered to be an alternative material to cement and can be used for the production of prefabricated elements, structural elements, adhesive mortars or insulating materials [45][46][47].…”

“…However, the potential use of glass waste as a substitute for conventional precursors is limited. In most studies, the optimal content of glass waste as a precursor is up to 15% [36,37,39,42]. Therefore, the aim of this research is to increase the content of soda-lime waste glass (SLWG) in metakaolin-based geopolymers.…”