Effect of Na2SiO3/NaOH rate and natural zeolite content on basalt fiber reinforced eco-efficient slag-based geopolymer mortar synthesis

Abstract

Considering that industrial wastes such as granulated blast furnace slag (GBFS) and fly ash (FA) will be released less or more in the future, developing geopolymer composites with natural pozzolans is a critical issue today. In this study, geopolymer composites with different SS (sodium silicate)/SH (sodium hydroxide) rates (2.0, 2.5 and 3.0) were produced by NZ reinforcement at 5%, 10% and 15%, and their physicomechanical, transport, high-temperature resistance, microstructure, carbon footprint and cost features were investigated. Geopolymer composites had been heat-cured for 8 h at 80 °C. The porosity of geopolymer composites varies between 5.2 and 7.2%, while their water absorption is between 3.4 and 6.9%. The dry unit weight of all geopolymer composites is less than 2300 kg/m3. The compressive strength of the geopolymer composite with an SS/SH rate of 3 and an NZ rate of 5% was about 75 MPa, and the compressive strength of the geopolymer composite with an SS/SH rate of 2 and an NZ rate of 15% was about 40 MPa. The capillary water absorption value of geopolymer composites is generally less than 1 kg/m2. While the compressive strength of geopolymer composites exposed to 600 °C ranged from 21.2 to 40.5 MPa, using 5% and 10% NZ generally improved the high-temperature resistance. The carbon emission of geopolymer composites was between 391.4 and 400.8 kgCO2/kg, while the cost increased only slightly with increasing NZ content. As a result, NZ content of 10% when the SS/SH rate is 2.5 and NZ content of 5% when the SS/SH rate is 3 improves many features of geopolymer composites.