The Impact of the Amount of Water Used in Activation Solution and the Initial Temperature of Paste on the Rheological Behaviour and Structural Evolution of Metakaolin-Based Geopolymer Pastes

Abstract

This study aimed to determine the impact of the initial temperature of the paste (from 5 °C to 35 °C) and the addition of water, which reflects a decrease in the molarity of activation solutions (AS) by diluting 10 M NaOH with distillate water, on the rheological properties of geopolymer pastes. Additionally, this resulted in changes to the physical–mechanical properties of geopolymers after curing. A higher amount of water in the AS composition and higher initial paste temperature led to an increase in the spread values up to 28% and decreases viscosity. A smaller amount of water in the AS composition and a higher initial paste temperature accelerated the speed of the geopolymer structure formation up to 1.5 times during the curing period, increased compressive strength and reduced apparent porosity and pore size. X-ray diffraction confirmed the compressive strength test results and revealed that the lower amount of water in the AS and the higher initial paste temperature for the geopolymer preparation significantly affected the mineral formation and physical and mechanical properties of the samples.

Rheological, fresh, and mechanical properties of mechanochemically activated geopolymer grout: A comparative study with conventionally activated geopolymer grout

“…Thus, it caused an increase in the degree of dissociation in the solution, which in turn is responsible for the reduction in the initial viscosity of MG [91]. Similar behavior was reported by Vitola, Laura, et al [92] and Yang et al [93].…”

“…The initial temperature of MG increased approximately by 35% in comparison with CG grout (23 • C). As mentioned previously in section 3.2.1, the increase in initial temperature increased the dissolution process of geopolymer grout, and the number of ions in a solution increased with the increasing the initial temperature of MG grout, and dissociation increases since the bonds in the electrolyte molecules are activated, resulting in low yield stress and plastic viscosity [92]. Further investigations must be conducted to thoroughly assess the effect of the increase in the initial temperature on the rheological properties of MG grout.…”

Influence of Liquid-to-Solid and Alkaline Activator (Sodium Silicate to Sodium Hydroxide) Ratios on Fresh and Hardened Properties of Alkali-Activated Palm Oil Fuel Ash Geopolymer

“…Given the high demand for industrial construction materials, finding ways to prevent the scarcity of natural resources, aside from considering the usage of waste material in the construction industry, has become a main concern for the industry. The use of geopolymers is one way to reduce waste, especially industrial waste, and to explore innovative methods for waste management [ 6 ]. A mind-set of ‘turn waste into wealth’ is causing the current shift towards environmentally friendly development [ 7 ].…”

Developing Mix Proportions for Class C Fly Ash-Based Alkali-Activated 3D-Printed Concrete Mixtures

“…For example, when the W/FA was increased from 0.34 to 0.40, the OT increased from 2.5 min to 7.0 min, but as the W/FA was increased to 0.42, the OT increased significantly to 31 min. AAM is sensitive to the W/FA where a small change in the added extra water can significantly change the viscosity of AAM, thus resulting in substantial changes in the workability and setting time, that is, OT (47,55).…”