Performance Optimization of FA-GGBS Geopolymer Based on Response Surface Methodology

Abstract

Many scholars have focused on the workability and mechanical properties of fly ash (FA)- ground granulated blast furnace slag (GGBS) geopolymer. To enhance the compressive strength of geopolymer, zeolite powder was added in the present study. A series of experiments were carried out to investigate the effect of using zeolite powder as an external admixture on the per-formance of FA-GGBS geopolymer, 17 sets of experiments were designed and tested to deter-mine the unconfined compressive strength based on the response surface methodology, and then, the optimal parameters were obtained via modeling of 3 factors (zeolite powder dosage, alkali exciter dosage, and alkali exciter modulus) and 2 levels of compressive strength (3 d and 28 d). The experimental results showed that the strength of the geopolymer was the highest when the three factors were 13.3%, 40.3%, and 1.2. Finally, a combination of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and 29Si nuclear magnetic resonance (NMR) analysis was used to conduct micromechanical analysis and explain the reaction mechanism from a microscopic perspective. The SEM and XRD analysis revealed that the microstructure of the geopolymer was the densest when the zeolite powder was doped at 13.3%, and the strength increased accordingly. The NMR and Fourier transform infrared spectroscopy analyses revealed that the absorption peak wave number band shifted toward the lower wave number band under the optimal ratio, and the silica–oxygen bond was replaced by an aluminum–oxygen bond, which generated more aluminosilicate structures.

Optimization of Composite Cavitation Nozzle Parameters Based on the Response Surface Methodology

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On Thermal Insulation Properties of Various Foaming Materials Modified Fly Ash Based Geopolymers

“…The reduced carbon emission geopolymers (first proposed and invented by Davidovits in 1978 [7]) have gained increasing attention around the world. Geopolymer is a tetrahedral network system composed of poly(aluminosilicate) (Si-O-Al-O) [8], which is produced by geopolymerization [9] using aluminosilicate-rich materials (e.g., fly ash [10], uncalcined coal gangue [11], slag [12], and other factory sweepings) and alkali activator. Furthermore, clayey materials and construction and demolition wastes (including ceramic waste) are also used in the geopolymerization process [13].…”