Anhydrous Borax in Fly Ash–Slag Geopolymer Concrete: Evidence and a Research Framework
DOI:
https://doi.org/10.63313/FE.9019Keywords:
Anhydrous Borax, Fly Ash–Slag Geopolymer Concrete, Setting Control, Workability Retention, Research FrameworkAbstract
Rapid setting and loss of workability can restrict the use of fly ash–slag geopolymer concrete, particularly when slag is introduced to support strength development under ambient conditions. This narrative review examines the evidence for borate-mediated reaction control and develops a research framework for externally added anhydrous borax. Published studies are compared by precursor composition, activation route, borax hydration state, and the relationship between fresh and hardened properties. The synthesis identifies a recurring possibility of delayed setting, but the associated strength response varies with formulation and age. Evidence obtained with hydrated borax, elevated-temperature fly ash systems, or combined admixtures does not establish a transferable dosage for anhydrous borax in concrete. A staged framework is therefore proposed in which matched paste and mortar screening precede verification across concrete formulations with different target strengths. The base activator and water contents remain fixed, while borax-derived sodium is reported separately. Dosage selection combines a usable placement window, flow retention, stability, and strength requirements; full compressive responses and complementary microstructural measurements then test the consequences of the selected treatment. The framework distinguishes observed retardation from proposed surface inhibition and network modification mechanisms. Its contribution is a traceable route for evaluating a formulation-specific performance window, without presuming an optimum dosage or presenting planned experiments as completed results.
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