Ambient and Heat-Cured Geopolymer Composites: Mix Design Optimization and Life Cycle Assessment

Abstract

The feasibility of producing sustainable cement-free composites and its environmental impact were investigated in this research. Experimental parametric evaluation was carried out in this regard to explore the optimum mix design of the composites. The effect of synthesis parameters and curing conditions on the behavior of the produced geopolymer composites was investigated. The studied parameters included the molarity of the sodium hydroxide solution (12 M, 14 M, and 16 M), the sodium silicate to sodium hydroxide ratio (1, 1.5, 2, and 2.5), the fluid to binder ratio (0.6, 0.65, and 0.7), and the age. The curing conditions included ambient curing and heat treatment at 40 °C, 80 °C, and 120 °C for 24 h, 48 h, and 72 h. In addition, life cycle assessment was performed to compare the environmental impact of geopolymer and cementitious composites. The results reflected the possibility of producing geopolymer composites with significant positive environmental impacts over traditional cementitious composites. The synthesis parameters played a major role in the behavior of the produced geopolymers. Heat curing was necessary for the geopolymer mortar to achieve high early strength. However, strength development with age was more obvious for ambient-cured specimens than heat-cured specimens. The optimum fluid to binder ratio used in this research was 0.6. For this ratio, the compressive strength increased as the molarity of the sodium hydroxide solution increased for all sodium silicate to sodium hydroxide ratios. Finally, SEM images showed that the higher the molarity and as the amount of reacted FA particles increased, the better the microstructure of the geopolymer mortar was and the fewer pores the matrix had.

Modified Bacteria Incorporated Geopolymer - A Qualitative Approach for an Eco-friendly, Energy-efficient and Self-healing Construction Material

“…Our results suggest that ambient temperature air curing is the most suitable curing condition for achieving the highest mechanical strengths (compressive, tensile and flexural) and extended longevity of the bacteria incorporated geo-polymeric mortars. Rabie et al [32] have investigated the feasibility of producing sustainable cement-free composites and its environmental impact, which corroborates with our experimental results. High temperature air curing (90 o C heat curing for 72 h) also showed good performance on mechanical strengths and durability of the bacterium incorporated geo-polymeric materials (Table 2).…”

Development and characterization of a composite material with geopolymer matrix obtained by incorporation of microparticles from plastic bottles

“…The curing conditions included ambient curing of specimens with age, according to results found in Ref. [ 23 ], and the composites obtained are described in Table 1 .…”

Geopolymer: A Systematic Review of Methodologies

“…Ref. [ 147 ] studied the performance of ambient and heat-cured geopolymer composites. They found that 1-day heat cured geopolymer mortar gained more than twice the compressive strength of 28 days ambient cured geopolymer mortar.…”

“…The production of geopolymer mortar is more environmentally friendly compared to OPC mortar. For example, Figure 18 shows that 1 m 3 of geopolymer mortar produces 72% GWP, 65% AP, 41% EP, and 29% ADP less than the production of 1 m 3 of OPC [ 147 ]. The main processes studied were the extraction of source materials, transportation of the material, and the production of the final product.…”