Investigation the mechanical, durability, heating Investigation the mechanical, durability, heating struggle, thermal gravimetric examination, and microstructure of geopolymer ceramic concrete incorporating nano-silica and nano-Soda-Cans

Abstract

Geopolymer concrete (GPC) has been developed to reduce the environmental footprint of cement production. Practical applications for GPC remain mostly limited to the production of precast concrete, and heat treatment has been identified as the leading barrier to wider adoption of this promising technology. In this research, this barrier was faced with nano-alumina produced from waste materials: recycled aluminum beverage cans and waste ceramic used in the GPC as a coarse aggregate (CC) and as fine aggregates (FC). Fifteen mixes were prepared and tested to determine the effect of replacing conventional fine and coarse aggregates with CC and FC at replacement levels up to 100 % in GPC. The effect of adding nano-silica (NS) and NA at different dosages (2 %, 3 %, and 4 % of binder content) on GPC performance was also investigated. The properties considered in this work are slump flow, initial setting time, final setting time, densities—wet, dry, and oven-dried—and mechanical strengths including compressive strength ($f_c$), tensile strength ($f_t$), bond strength ($f_b$), and flexural strength ($f_f$). Other tests such as water absorption (WA%), residual compressive strength ($f_c^{\prime }$), and residual density ($D\prime$) when exposed to higher temperatures (up to 800 °C), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) of GPC mixes, were also carried out. It was shown in the experimental results that alkaline activators had strong reducing effects on setting times of GPC. That is, it obtained an initial set in 45 minutes and a final set in 6 hours at room temperature. The mechanical properties of the control mix (GVC) at 28 days were: $f_c=38$ MPa, $f_t=4.14$ MPa, $f_b=7.1$ MPa, $f_f=5.6$ MPa, and WA% = 1.8 %. Concrete with 25 % CC and 25 % FC replacement demonstrated enhanced mechanical and thermal properties. Still, further replacement of CC or FC beyond 50 % resulted in deterioration in both mechanical and durability properties. The addition of NS and NA improved the performance of GPC compared to GVC, with maximum improvements at 3 % and 4 %, respectively. The NA exhibited better mechanical properties, residual strength ($f_c^{\prime }$), and thermal stability by TGA and SEM tests than NS at all levels of substitution. The addition of 4 % NA enhanced the control mix $f_c,f_t,f_b$, and $f_f$ by 41.9 %, 64 %, 54.7 %, and 69.6 %, respectively, with a slight increase in WA% to 0.41 %. Moreover, $f_c^{\prime }$ exhibited outstanding 213 % enhancement at 800 °C. The NA4 mix had the most desirable morphological features and thermal stability, as evidenced by SEM and TGA analyses.