Effect of curing temperature, silica fume, and waste tire rubber aggregate on material characterization of lightweight geopolymer composite

This study investigates the potential effect of curing temperature (80 degrees C and 100 degrees C), the effect of using waste tire rubber aggregates (WTRA), and silica fume (SF) on the properties of lightweight geopolymer (LG) composite. In LG, SF replaced 20 % of the ground granulated blast furnace slag (GGBS), and WTRA replaced pumice aggregate to varying degrees (15 %, 30 %, and 45 % by volume). The physical properties of the LG composite were assessed through apparent porosity, water absorption, and hardened density. The mechanical properties were examined by testing compressive strength (CS) and flexural strength (FS). The effect of high temperature (300 degrees C and 600 degrees C) was examined on CS and mass loss of LG composite. The durability of the LG composite was analyzed using mercury intrusion porosimetry (MIP), capillary water absorption, freeze-thaw, and thermal conductivity. The material characterization of the composite was done using scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential thermogravimetry (DTG) curves. After 28 days, LG composites showed increased porosity and water absorption with the increased WTRA and SF, with higher values at 100 degrees C. Compressive and flexural strengths decreased with the increased WTRA and SF, especially at higher temperatures. The TGA-DTG curves show that the LG-0-80 mix had the lowest mass loss (15.25 % at 400 degrees C and 19.36 % at 600 degrees C), while the LG-SF-45-100 mix had the highest mass loss (22.22 % and 24.53 %, respectively). XRD and TGA-DTG analyses reveal that using SF increases Ca(OH)2 peaks and alters the geopolymer composition, improving the mechanical performance of the LG-SF-0-80 mix and enhancing the thermal stability of the composites.