Abstract
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.
Highlights
Geopolymers are an advantageous alternative to Portland cement in certain applications
Geopolymer binders can be obtained by the alkaline activation of aluminosilicate-rich raw materials with low calcium content, such as calcined clays and fly ashes, forming an amorphous or nanocrystalline sodium-aluminosilicate hydrates gel (N-A-S-H), with a tridimensional structure charge-balanced by cations from an alkali activator (BERNAL; PROVIS, 2014; PROVIS; LUKEY; VAN DEVENTER, 2005)
Focusing on the geopolymerization reaction, this study evaluates the efficiency of alkaline activation of metakaolin using Potassium Hydroxide and Potassium Silicate solution with and without partial replacement of 12.5% of the precursor weight by microparticles of glass waste, using room temperature and thermal curing
Summary
Geopolymers are an advantageous alternative to Portland cement in certain applications. Depending on the raw materials and the processing conditions, these materials can present high initial compressive strength, low shrinkage, greater/lower consistency, resistance to acid and sulfate attack, and better thermal stability at high temperatures (RIAHI et al, 2020; SINGH; MIDDENDORF, 2020; TORRES-CARRASCO; PUERTAS, 2017). These binders present long-term mechanical strength and durability greater than Portland cement (DAVIDOVITS, 2017; HÁJKOVÁ, 2018; YASERI et al, 2017). In the one-part method, a dry mixture of an alkaline source powder and a precursor receive water addition (KOLOUŠEK et al, 2007)
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