Abstract
Alkali-activated binders (AABs) are developed using a dry mixing method under ambient curing incorporating powder-form reagents/activators and industrial waste-based supplementary cementitious materials (SCMs) as precursors. The effects of binary and ternary combinations/proportions of SCMs, two types of powder-form reagents, fundamental chemical ratios (SiO2/Al2O3, Na2O/SiO2, CaO/SiO2, and Na2O/Al2O3), and incorporation of polyvinyl alcohol (PVA) fibers on fresh state and hardened characteristics of 16 AABs were investigated to assess their performance for finding suitable mix compositions. The mix composed of ternary SCM combination (25% fly-ash class C, 35% fly-ash class F, and 40% ground granulated blast furnace slag) with multi-component reagent combination (calcium hydroxide and sodium metasilicate = 1:2.5) was found to be the most optimum binder considering all properties with a 56 day compressive strength of 54 MPa. The addition of 2% v/v PVA fibers to binder compositions did not significantly impact the compressive strengths. However, it facilitated mitigating shrinkage/expansion strains through micro-confinement in both binary and ternary binders. This research bolsters the feasibility of producing ambient cured powder-based cement-free binders and fiber-reinforced, strain-hardening composites incorporating binary/ternary combinations of SCMs with desired fresh and hardened properties.
Highlights
Geopolymers are classified as alkali-activated materials (AAMs) produced from the activation of aluminosilicate-rich precursors by alkaline reagents [1]
This paper presents the results of a research study to address the above-mentioned research gaps
The influence of mixes were developed on the incorporating polyvinyl alcohol (PVA) fibers (2% v/v) the binder compositions on the shrinkage/expansion basis of the optimized mix regimes compositions of reagent proportion/dosage
Summary
Geopolymers are classified as alkali-activated materials (AAMs) produced from the activation of aluminosilicate-rich precursors by alkaline reagents [1]. The novel aspects of this paper include the use of binary/ternary proportions/combinations of high/low calcium industrial waste-based precursors, two combinations/dosages of the powder form calcium/sodium-based reagents, and PVA fibers for the development of AABs using one-part dry mixing technique established in authors previous studies [24,42]. The performance of developed one-part ambient cured binders is evaluated compared to conventional two-part heat-cured counterparts incorporating low calcium precursors and sodium-based reagents from previous research studies. The experimental program consisted of a comprehensive performance evaluation of the developed 16 AAB compositions in terms of fresh state (workability, setting times, and time-dependent heat evolution), compressive strength (binders with and without fibers), durability (shrinkage/expansion and mass change of binders with and without fibers in water and ambient curing regimes), and microstructural (based on SEM/EDS and XRD analyses) characteristics
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