Revealing the Influence of Microparticles on Geopolymers’ Synthesis and Porosity

Abstract

Geopolymers are zeolites like structures based on hydrated aluminosilicates units of SiO4 and AlO4. These units, known as poly(sialate), poly(sialate)-siloxo or poly(sialate)-disiloxo are chemically balanced by the group I cations of K+, Li+, or Na+. Simultaneously, the chemical reaction of formation, known as geopolymerization, governs the orientation of the unit, generating mesoporous structures. Multiple methods can be used for pore structure and porosity characterization. Among them, nuclear magnetic resonance (NMR) relaxometry allows the detection of the porous structure in a completely nonperturbative manner. NMR relaxometry may be used to monitor the relaxation of protons belonging to the liquid molecules confined inside the porous structure and, thus, to get access to the pore size distribution. This monitoring can take place even during the polymerization process. The present study implements transverse relaxation measurements to monitor the influence introduced by the curing time on the residual liquid phase of geopolymers prepared with two different types of reinforcing particles. According to our results, the obtained geopolymers contain three types of pores formed by the arrangement of the OH− and Si groups (Si-OH), Si-O-Si groups, Si-O-Al groups, and Si-O rings. After 48 days, the samples cured for 8 h show a high percentage of all three types of pores, however, by increasing the curing time and the percentage of reinforcing particle, the percent of pores decrease, especially, the gel pores.

Influence of 1.5 wt.% Bi on the Microstructure, Hardness, and Shear Strength of Sn-0.7Cu Solder Joints after Isothermal Annealing

“…For example, Chen et al [ 9 ] pointed out that the Cu 6 Sn 5 has a slower rate of growth than Cu 3 Sn under isothermal annealing conditions. Simultaneously, the exaggerated IMC layer’s growth may also deteriorate the solder joints’ reliability [ 11 ]. Shen et al [ 12 ] also posited that the IMC layer rises with annealing time due to the solid-state diffusion taking place between Cu atoms from the Cu-pad and Sn from the bulk solder.…”

Performance of Sn-3.0Ag-0.5Cu Composite Solder with Kaolin Geopolymer Ceramic Reinforcement on Microstructure and Mechanical Properties under Isothermal Ageing

“…For example, Cu 3 Sn starts to grow at temperatures below 60 • C and increases at longer duration. Therefore, isothermally age-testing is typically used to simulate the changes of microstructure and performance of the solder joints during the actual working conditions [11,[19][20][21].…”

Key Factors Determining the Self-Healing Ability of Cement-Based Composites with Mineral Additives

“…The self-healing rate may decrease when mineral additives are used in large quantities as a substitute for cement, because the pozzolanic reaction is limited by the availability of calcium hydroxide [30]. In such cases, the hydration kinetics of cementitious composites with mineral additives can be low in the first weeks, so in recent years, methods to stimulate and accelerate the self-healing process were proposed: the use of alkaline solutions [5,31], the mixing of different mineral additives [32] including the use of calcareous fly ash [33], lime powder [34] or hydrated lime [35] to increase the calcium content.…”