Effects of load types and critical molar ratios on strength properties and geopolymerization mechanism

Abstract

In this study, the effect of SiO2/Al2O3 (S/A), Na2O/Al2O3 (N/A) and H2O/Na2O (H/N) molar ratios on bending and compressive strength of geopolymer were investigated. The geopolymerization mechanism was also analyzed from microstructure difference by FTIR. The experimental results showed that compressive strength and bending strength of geopolymer has an opposite reaction under different critical molar ratios. The increase of S/A molar ratio and the decrease of N/A and H/N molar ratios have resulted in an increase of the compressive strength. However, it caused a noticeable decrease in bending strength. The microstructure of geopolymer indicated that the degree of polymerization and cohesion of geopolymer have systematical depending on these critical molar ratios, making the mechanical properties of geopolymer susceptible to different types of loads. This paper reveals the relationship between the microstructure of geopolymer and different mechanical properties and helps to selectively prepare corresponding geopolymer for different loading patterns.

Review of Geopolymer Nanocomposites: Novel Materials for Sustainable Development

“…The addition of nanosilica to fly-ash-based geopolymers increases the activity of the matrix material, and thus accelerates the geopolymerization process, increasing the length of the C-S hydrogen gel chain, which gives the effect of filling with small particles. Finally, the fly ash and nano-SiO 2 geopolymerize to form a three-site reticular inorganic gel material with Si-Al-O cross-linking [42].…”

Evaluation of the Potential of Metakaolin, Electric Arc Furnace Slag, and Biomass Fly Ash for Geopolymer Cement Compositions

“…Taking this into account, an estimation of the dissolved amounts of silicate and aluminate species is important in designing the GPC mix because these seem more likely related to the actual amounts taking part in the formation of the GPC matrix than the total SiO 2 and Al 2 O 3 present in the precursors [ 30 ]. However, most published works on GPC mix design have relied on the total oxide content reported in the precursors’ chemical analysis to calculate chemical ratios and mix proportions [ 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. In fact, only a few recent research examples have explicitly investigated the relationship between the properties of the obtained GPC and the measured dissolution extent of silicates and aluminates from the precursors used [ 37 , 38 ].…”