Rheology, agglomerate structure, and particle shape of fresh geopolymer pastes with different NaOH activators content

Zhang, Dawang; Wang, Dongmin; Liu, Ze; Xie, Fuzhu

doi:10.1016/j.conbuildmat.2018.07.205

Cited by 85 publications

(21 citation statements)

References 20 publications

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“…The mini-slump test was performed immediately after the pastes were mixed (and at 10 min and 20 min). It is known that the fluidity of fresh geopolymer pastes, tested by the mini-slump test, is closely related to the yield stress and plastic viscosity of the pastes [10,37]. An increase in the water/10 M NaOH ratio in the AS causes an increase of spread diameter.…”

Section: The Spread Of Geopolymer Pastesmentioning

confidence: 99%

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

et al. 2020

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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.

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Section: The Spread Of Geopolymer Pastesmentioning

confidence: 99%

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

et al. 2020

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“…Similar test results were also observed in this research. The effects of the concentration of alkali metal hydroxide on properties of geopolymer are dependent on the change of zeta potential in the alkaline activator [ 57 ].…”

Section: Resultsmentioning

confidence: 99%

Protective Geopolymer Coatings Containing Multi-Componential Precursors: Preparation and Basic Properties Characterization

et al. 2020

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This paper presents an experimental investigation on geopolymer coatings (GPC) in terms of surface protection of civil structures. The GPC mixtures were prepared with a quadruple precursor simultaneously containing fly ash (FA), ground granulated blast-furnace slag (GBFS), metakaolin (MK), and Portland cement (OPC). Setting time, compressive along with adhesive strength and permeability, were tested and interpreted from a perspective of potential applications. The preferred GPC with favorable setting time (not shorter than 120 min) and desirable compressive strength (not lower than 35 MPa) was selected from 85 mixture formulations. The results indicate that balancing strength and setting behavior is viable with the aid of the multi-componential precursor and the mixture design based on total molar ratios of key oxides or chemical elements. Adhesive strength of the optimized GPC mixtures was ranged from 1.5 to 3.4 MPa. The induced charge passed based on a rapid test of coated concrete specimens with the preferred GPC was 30% lower than that of the uncoated ones. Setting time of GPC was positively correlated with η[Si/(Na+Al)]. An abrupt increase of setting time occurred when the molar ratio was greater than 1.1. Compressive strength of GPC was positively affected by mass contents of ground granulated blast furnace slag, metakaolin and ordinary Portland cement, and was negatively affected by mass content of fly ash, respectively. Sustained seawater immersion impaired the strength of GPC to a negligible extent. Overall, GPC potentially serves a double purpose of satisfying the usage requirements and achieving a cleaner future.

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“…It was found that the excellent fluidity of AAM primarily results from the high electrostatic repulsion of particles surface caused by the fast diffusion rate of Al and Si in high content alkalinity. [14,22]. Moreover, there is no colloidal interaction or flocculation structure between fresh AAM particles, and lots of residual water actually exists as freely moving status which do not take part in the reaction, resulting in poor cohesiveness and viscosity of AAM due to the water dilution effect [23].…”

Section: Rheology and Workabilitymentioning

confidence: 99%

“…It should be noted that too-low yield stress of coating may bring about sagging or even water/solid separating due to poor cohesiveness, and while too-high yield stress may cause stiffing, the coating could not be freely coated or brushed into a continual film. As AAM is a high reactive system and easily solidified, the evolution of coating flow behavior with time is one of the very important properties which relates to the operable time and workability during real application [22,23,27]. The rheological evolution of coating with setting time was investigated, the rheological parameters including yield stress, plastic viscosity, and thixotropy are pasted in Figure 3.…”

Section: Rheology and Workabilitymentioning

confidence: 99%

“…In this regard, AAM has become a novel candidate for developing inorganic coatings for architectural decorating.The construction process of decorative coatings requires good plastic formable capacity ensuring the coating is flexibly formed into a complex layer appearance so that it meets people's aesthetic expectations, which highly relates to the plastic viscosity and thixotropy. Few papers have investigated the relationship between different alkaline activators and solid particles on the rheological behavior of AAM [20][21][22], but studies have found that AAM often shows the excellent fluidity due to the high electrostatic repulsion of the particle surface which was caused by the fast diffusion rate of the Al and Si elements in high content [OH] − [22,23]. Furthermore, there is no colloidal interaction or flocculation structure between AAM particles, and lots of residua water is present in aluminosilicates particles in a freely moving status which does not take part in reaction [20,23].…”

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confidence: 99%

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One-Part Plastic Formable Inorganic Coating Obtain from Alkali-Activated Slag /Starch(CMS) Hybrid Composites

Qin

Lin

et al. 2020

Molecules

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Coating technology can be applied to decorate building constructions. Alkali-activated materials (AAM) are promising green and durable inorganic binders which show potential for development as innovative coating. In the paper, the possibility of using AAM composited with starch (CMS) as a novel plastic formable inorganic coating for decorating in building was investigated. The rheological properties, including plastic viscosity, yield stress, and thixotropy were considered to be critical properties to obtain the working requirements. Four different mixtures were systematically investigated to obtain the optimum formulation, and then were used to study their hardened properties, such as mechanical strengths (compressive, flexural, and adhesive strength), drying shrinkage, cracking behavior, and microstructure. Study results found that CMS could quickly and efficiently be hydrolyzed in an alkaline solution to produce organic plastic gel which filled in AAM paste, leading to the significant improvement of coating consistency, plastic viscosity, and thixotropy. The optimum coating composited with 15.40 wt% CMS shows a relatively stable rheological development, the setting time sufficient at higher than 4 h. Furthermore, CMS shows a significant positive effect on the cracking and shrinkage control due to padding effect and water retention of CMS, which results in no visible cracks on the coating surface. Although the mechanical strength development is relatively lower than that of plain AAM, its value, adhesive strength 2.11 MPa, compressive strength 55.09 MPa, and flexural strength 8.06 MPa highly meet the requirements of a relevant standard.

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Rheology, agglomerate structure, and particle shape of fresh geopolymer pastes with different NaOH activators content

Cited by 85 publications

References 20 publications

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

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

Protective Geopolymer Coatings Containing Multi-Componential Precursors: Preparation and Basic Properties Characterization

One-Part Plastic Formable Inorganic Coating Obtain from Alkali-Activated Slag /Starch(CMS) Hybrid Composites

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