Effect of fly ash microsphere on the rheology and microstructure of alkali-activated fly ash/slag pastes

Yang, Tao; Zhu, Huajun; Zhang, Zuhua; Gao, Xuesong; Zhang, Changsen; Wu, Qisheng

doi:10.1016/j.cemconres.2018.04.008

Cited by 271 publications

(50 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The composites were activated by the addition of hydrolyzed lime in the amount of 0%, 2%, 4% and 6% of the mass of the added ODFA (series "2H 0 ", "2H 2 ", "2H 4 ", "2H 6 ", "3H 0 ", "3H 2 ", "3H 4 ", "3H 6 ") (Activation of FA can be carried out with two methods, mechanical and chemical. The mechanical method consists in the fragmentation of FA [49] and is expensive. Chemical activation is achieved by the addition of activators to the composite, e.g.…”

Section: Methodsmentioning

confidence: 99%

Old Dumped Fly Ash as a Sand Replacement in Cement Composites

Harasymiuk

Rudziński

2020

Buildings

View full text Add to dashboard Cite

The use of industrial residues to replace natural resources for the production of building materials is economically and ecologically justified. Fly ash (FA) taken directly from electro-filters is commonly used as a cement replacement material. This is not the case, however, for old dumped fly ash (ODFA) that has been accumulating in on-site waste dumps for decades and currently has no practical use. It causes environmental degradation, which is not fully controlled by the governments of developed countries. The aim of the study was to assess the possibility of using ODFA as a partial replacement for sand in cement composites. ODFA replaced part of the sand mass (20% and 30%) in composites with a limited amount of cement (a cement-saving measure) and sand (saving non-renewable raw material resources). ODFA was activated by the addition of different proportions of hydrated lime, the purposes of which was to trigger a pozzolanic reaction in ODFA. The quantitative composition of the samples was chosen in such a way as to ensure the maximum durability and longevity of composites with a limited amount of cement. The 28-day samples were exposed to seawater attack for 120 days. After this period, the compressive strength of each sample series was determined. The results suggest the possibility of using ODFA with hydrated lime to lay town district road foundations and bike paths of 3.5 to 5 MPA compressive strength. What is more, these composites can be used in very aggressive environments.

show abstract

Section: Methodsmentioning

confidence: 99%

Old Dumped Fly Ash as a Sand Replacement in Cement Composites

Harasymiuk

Rudziński

2020

Buildings

View full text Add to dashboard Cite

show abstract

“…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%

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

Qin

Lin

et al. 2020

Molecules

View full text Add to dashboard Cite

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.

show abstract

“…The mass loss fraction between 600 and 700 °C is assigned to the decomposition of calcite. The mass fraction of calcite decreases as the particle size of the silica flour becomes finer, indicating that more calcium is released from the decomposition reaction to the solution for the formation of the gel phase [30]. The XRD patterns of samples exposed to 80 °C for 7 days are shown in Figure 5.…”

Section: Mineral Compositionmentioning

confidence: 99%

Influence of the Particle Size Distribution of Silica Flour on the Mechanical and Microstructural Properties of Oil Well Cement Paste Exposed to HTHP Conditions

Xie¹

2019

Ceramics - Silikaty

View full text Add to dashboard Cite

Silica flour is used to mitigate the strength retrogression and microstructure degradation problems of oil well cement paste in high temperature wells. This study investigates the effects of the particle size distribution of silica flour on the thermal stability of cement paste. After 7 days of hydrothermal curing at 80 °C, the cement paste was exposed to further aging for 7 or 28 days under high temperature and high pressure (HTHP) conditions in a sealed chamber at 260 °C (500 °F) and 21 MPa (2900 psi). The results show that 43% silica flour by weight of cement (BWOC) mitigates the strength degradation of silica-stabilized Portland cement (SSPC), and course silica flour (63.13 and 48.25 µm) maintains the strength stability of SSPC better than fine silica flour (3.25 µm). The transformation of C-S-H gel to xonotlite in SSPC was influenced by the silica particle size. The relatively fine silica flour (d 50 = 3.25 µm) accelerates the consumption of calcium hydroxide during the pozzolanic reaction, resulting in a poorer strength stability of SSPC than the courser silica flour (d 50 = 63.13 and 48.25 µm). The silica flour with an average particle size of 48.25 µm is more conducive to crystallization of xonotlite on the crystal plane corresponding to a diffraction angle of 25.5° than the other size silica flour.

show abstract

Effect of fly ash microsphere on the rheology and microstructure of alkali-activated fly ash/slag pastes

Cited by 271 publications

References 48 publications

Old Dumped Fly Ash as a Sand Replacement in Cement Composites

Old Dumped Fly Ash as a Sand Replacement in Cement Composites

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

Influence of the Particle Size Distribution of Silica Flour on the Mechanical and Microstructural Properties of Oil Well Cement Paste Exposed to HTHP Conditions

Contact Info

Product

Resources

About