Utilizing porcelain tile polishing residue in eco-efficient high-strength geopolymers with steel microfibers

Abstract

Geopolymers are an alternative that produces low environmental impact binders with satisfactory mechanical properties. This research evaluated the influence of adding steel microfibers to a binary geopolymer matrix composed of metakaolin and ceramic tile polishing residue. Three mortar compositions (1:2, 1:3 and 1:4 cement:sand mass ratios) were produced with three microfiber concentrations (vf = 0.45, vf = 0.90 and vf = 1.35 % of total volume). The mechanical properties were evaluated by testing compressive strength, dynamic modulus of elasticity, flexural strength, and toughness. For 1:3 mortar, autogenous shrinkage measurements were performed for the 3 microfiber concentrations. Equivalent carbon dioxide emissions and binder intensity were also quantified. The mechanical properties classify the geopolymer concrete as high strength, achieving up to 95 MPa (composition 1:3) of compressive strength at 28 days and low binder consumption (9.82 kg.m−3. MPa−1). An improvement in flexural tensile strength was observed as the concentration of steel microfibers increased, reaching 20 MPa with vf= 1.35 %. For the concentration vf= 0.90 %, there was a reduction of ∼38 % of the autogenous shrinkage measurements about the reference (vf=0.0 %) at 28 days. In addition, regarding the CO2 intensity index, the lowest values were obtained for the 1:3 compositions, being minimum for vf= 0.90 % (9.01 [kg. ECO2-eq /m³ of mortar]/MPa), producing geopolymeric composites with low CO2 emissions, allowing the production of construction materials with low environmental impact.