Performance assessment and cost analysis of slag/metakaolin based rubberized semi-lightweight geopolymers with perlite aggregate: Sustainable reuse of waste tires

Abstract

Low-carbon binders or industrial waste can reduce or even eliminate the demand for Portland cement and other natural resources, which reduces environmental pollution in accordance with the principles of sustainable development. The assessment of the mechanical, durability and microstructural properties of slag/metakaolin based rubberized semi-lightweight geopolymer composites (LWGC) with perlite aggregate (PA) is the main objective of this study. Waste tires aggregates (WTA) was produced from discarded waste tires, another environmental pollutant, and used in LWGC mixtures as substitution for the fine perlite aggregate by 0%, 20%, 45%, and 60% replacement. Metakaolin (MK) and ground granulated blast furnace slag (GBFS) were used as precursors in the synthesis of LWGC. Sodium hydroxide and sodium silicate solution was used as activators. Eight mixtures were created; four of them had 100% GBFS, while the other four contained 90% GBFS slag and 10% MK. All eight mixtures were then cured for 5 h at 60 °C and 100 °C. The effects of curing temperature, WTA, and MK on the compressive, flexural strength, physical properties, and sorptivity of the LWGC were examined as well as flowability. The performance of the blends at high temperatures, freeze thaw cycles and sulfate attack was also evaluated. Microstructure analyses of the mixtures were also done using SEM. CO2 emissions and costs of the mixtures were also evaluated. The results showed that inclusion of WTA instead of PA and MK instead of GBFS decreased the flow diameter. Thermal conductivity and dry density of the mixtures also decreased considerably with the addition of WTA. The findings showed that 10%MK incorporated mixture with 60%WTA produced a compressive strength of 25.10 MPa at curing temperatures of 100 °C. The results indicated compressive strength of MK incorporated mixture with 60%WTA increased by 48.10% and 31.20% at heat curing of 60 °C and 100 °C, respectively. The mixture WT60MK0 cured at 100 °C exhibited the best high temperature resistance and the same mixture also presented the best F-T performance regardless of curing temperature. The mixture WT40MK0 cured at 60 °C and the mixture WT60MK10 cured at 100 °C performed the best sulfate resistance.