Abstract
Geopolymer has been viewed as a potential, ideal and green material to replace cement. The recycling of Portland cement-based concrete as recycled aggregates was investigated diffusely, while the reuse of geopolymer was paid little attention. Exploring the feasibility and interfacial evolution of utilizing recycled geopolymer fine aggregate (RGFA) produced from waste geopolymer as the alternative for river sand (RS) was the core object in this research. Metakaolin to RS ratio of 1:2 and NaOH/Na2SiO3 ratio of 0.5 by weight, and 12 M of NaOH solutions were adopted to prepare the referenced geopolymer mortar. Then five RGFA replacement rates (0%, 20%, 50%, 80% and 100%) were used to prepare the NA (RGFA) mortar. The tests of compressive strength, flexural strength and water absorption of mortars were performed. SEM was used to observe the interfacial transition zone (ITZ) between RGFA and new generated geopolymer paste. Results proved that RGFA mortar exhibited comparable mechanical properties compared with the RS mortar when replacement rate was less than 50%. Furthermore, more compact ITZs were obtained in RGFA mortar. The decreasing mechanical properties of RGFA mortar was primarily attributed to the weak properties of RGFA itself. The filler effects and compact ITZs relieved the decline tendency of mechanical property of RGFA mortar. It was convinced that utilizing RGFA to replace RS as fine aggregates in the construction activities was promising.
Published Version
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