This work presents an evaluation of the application of iron ore tailing as primary precursor material to geopolymer production. Glass wool residue from the iron ore industry was also included as a blend material. Four mixtures of geopolymers were produced: one mixture using only iron ore tailing; three mixtures where the iron ore tailing was replaced by the glass wool residue, with a substitution ratio of 10%, 20% and 30% (in mass). Furthermore, three different grinding times and three NaOH solution concentration were applied. Compressive strength and flexural strength tests were performed in prismatic specimens at 7-days, and the microstructural analysis of the fragments was obtained by SEM analysis. QXRD analysis based on the Rietveld’s refinement method and TG/DTA analysis was applied for all specimens. The results showed the synthesis of a zeolite phase in all specimens, and the SEM micrographs showed a transformation process of the glass wool residue. Finally, high mechanical performances were found to the iron ore tailing-based geopolymer, reaching values higher than 100 MPa for compressive strength and 20 MPa for flexural strength. The obtained values are related to the grain packing improvements, geopolymerization products, and the glass wool residue working as a supplementary precursor material to the geopolymerization reaction. The result points to the potential of iron ore tailing and glass wool residue to geopolymers studies and application.

Introduction

Geopolymers are inorganic materials produced by alkaline activation of aluminosilicate materials through the geopolymerization reaction. In a highly concentrated alkali hydroxide or silicate solution, the aluminosilicates form a very stable material with amorphous or semi-crystalline polymeric structures with interconnected Si-O-Al-O-Si bonds called geopolymer [1–۳]. Typical examples of precursor materials to the geopolymer synthesis are metakaolin, fly ash and slag. Currently, Portland cement is the most used binder and one of the main responsible for the low environmental performance of conventional concrete. Cement production accounts for 5–۷% of total global CO2 emissions [4–۷]. Furthermore, concrete structures under specific environmental conditions exhibit some durability problems. This important aspect related to serviceability life of the structure is the capability to resist the mechanical actions, physical actions, and chemical aggressions that it is subjected to over their expected service life [8].