The incorporation of crumb rubber into fly ash-based geopolymer mortar reduces the CO₂ emissions due to the exclusion of ordinary Portland cement (OPC), the number of waste tires entering the landfills and the amount of natural mineral aggregate being used in mortar. The fly ash (class F) reacts with an alkaline solution such as sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) to produce aluminosilicate gel that binds the crumb rubber to produce a crumb rubber geopolymer mortar (CRGM). NaOH solution (12M) and Na₂SiO₃ solution ratio were fixed constantly at 2.5, and the solid to liquid ratio was fixed at 2 for all fly ash geopolymer mixture. The additions of crumb rubber in the mixture by weight of solid were varied at 0%, 5%, 10%, 15% and 20%, respectively. The outer layer used for the crumb rubber geopolymer sandwich wall panel (CRGSWP) was primaflex with 9 mm thickness. The effect of different percentage crumb rubber loading on the compressive strength of fly ash-based geopolymer mortar was determined. Results show that the compressive strength of the CRGM decreased with the increase of crumb rubber loading. The compressive strength of CRGM-0, CRGM-5, CRGM-10, CRGM-15 and CRGM-20 at 28 days were 40.48 MPa, 36.13 MPa, 29.69 MPa, 23.13 MPa and 20.13 MPa, respectively. This reduction is due to poor interfacial adhesion between crumb rubber and cement components; thus, the strength is reduced. For the effect of elevated temperature exposure on the performance of CRGM, the mortars, at 28 days of curing time, were exposed to an elevated temperature at 200°C, 400°C, 600°C and 800°C. Results of the CRGM show a reduction in compressive strength and density while the percentage of weight loss increased with increasing crumb rubber loading at all elevated temperature exposure. The performance of CRGM and CRGSWP were tested and compared for their mechanical properties, sound absorption and thermal conductivity. CRGSWP and CRGM show a reduction in compressive and flexural strength as the crumb rubber loading increases. The sound absorption percentage of CRGSWP was higher compared to CRGM, which means that the sound absorption of CRGSWP is better than CRGM. CRGSWP-20 shows the highest percentage of sound absorption by 57.32% for the low frequency and 70.01% for the high frequency. Thermal conductivity test of the CRGSWP-20 (0.074 W/mK) shows better k-value than CRGM-20 (0.298 W/mK). This thesis expands the contribution of the findings of different percentage crumb rubber loading on the properties of CRGM at room temperature and elevated temperature exposure and the mechanical and thermal properties of CRGSWP as sandwich wall panel application.
