The evolution of structural changes in ettringite during thermal decomposition

Hartman, Michael R.; Brady, Steven K.; Berliner, R.; Conradi, Mark S.

doi:10.1016/j.jssc.2006.01.038

Cited by 51 publications

(27 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…We interpret this as indicating that the basic structural units within the crystal structure remain intact but disorder with respect to each other and the free water in the structure. We can not tell if the amorphization is associated with dehydration of the structure as happens during thermal decomposition [14] 2 [28], Ni(OH) 2 and Co(OH) 2 [29] all exhibit a reversible pressure induced amorphization near 11GPa. These amorphizations have been found to be caused by disruption of the network of hydrogen bonds [30].…”

Section: Discussionmentioning

confidence: 96%

See 1 more Smart Citation

Effect of pressure on the crystal structure of ettringite

Clark

Colas

Kunz

et al. 2008

Cement and Concrete Research

View full text Add to dashboard Cite

show abstract

Section: Discussionmentioning

confidence: 96%

“…The thermal dehydration of ettringite has been studied [11,12,13,14] with some disagreement over the exact order of hydroxyl and free water leaving the crystal but general agreement over a large water loss at 110 o C followed by amorphization of the sample after the loss of 20 water units.…”

Section: Introductionmentioning

confidence: 99%

Effect of pressure on the crystal structure of ettringite

Clark

Colas

Kunz

et al. 2008

Cement and Concrete Research

View full text Add to dashboard Cite

show abstract

“…The absence of visible ettringite crystals can be explained by the great compactness of the matrix that has hindered the proper formation of the needle-like structure of ettringite and has favored the formation of small prismatic crystals, able to absorb water, to swell [57] (p. 52) and to induce tensile stresses in the paste because of its highly expansive behavior [56]. A recent study [65] reports that the decomposition of ettringite also only occurs after heating CSA samples at a temperature above 60 °C, which causes the loss of approximately 20 water molecules per formula and the transition of ettringite to an amorphous state, according to Hartman et al [66]. Figure 5c shows an SEM image of R3 GEO, which is characterized by small spherical particles of unreacted fly ash surrounded by a dense and continuous aluminosilicate mass.…”

Section: Microstructural Analyses Of Mortarsmentioning

confidence: 99%

Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

et al. 2017

View full text Add to dashboard Cite

This paper deals with the study of calcium sulfoaluminate (CSA) and geopolymeric (GEO) binders as alternatives to ordinary Portland cement (OPC) for the production of more environmentally-friendly construction materials. For this reason, three types of mortar with the same mechanical strength class (R3 ≥ 25 MPa, according to EN 1504-3) were tested and compared; they were based on CSA cement, an alkaline activated coal fly ash, and OPC. Firstly, binder pastes were prepared and their hydration was studied by means of X-ray diffraction (XRD) and differential thermal-thermogravimetric (DT-TG) analyses. Afterwards, mortars were compared in terms of workability, dynamic modulus of elasticity, adhesion to red clay bricks, free and restrained drying shrinkage, water vapor permeability, capillary water absorption, and resistance to sulfate attack. DT-TG and XRD analyses evidenced the main reactive phases of the investigated binders involved in the hydration reactions. Moreover, the sulfoaluminate mortar showed the smallest free shrinkage and the highest restrained shrinkage, mainly due to its high dynamic modulus of elasticity. The pore size distribution of geopolymeric mortar was responsible for the lowest capillary water absorption at short times and for the highest permeability to water vapor and the greatest resistance to sulfate attack.

show abstract

“…Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions has been an area of interest for many researchers, and it has been investigated in terms of waste stabilization using cementitious materials [1][2][3][4][5]. It is well known that Al-ettringite commonly plays an important role in the *Corresponding author.…”

Section: Please Scroll Down For Articlementioning

confidence: 99%

Development of a novel process for arsenic(V) removal from water using Fe-ettringite

Choi

Shim

Ghorpade

et al. 2014

Desalination and Water Treatment

View full text Add to dashboard Cite

A B S T R A C TThe Fe-ettringite formation and its arsenic removal capacity were investigated. The synergetic effect of initially injected ferric iron and formation of ettringite crystal in later stages contributed to improved removal capacity. The As(V) removal capacity by the formation of As(V)-containing Fe-ettringite (As/Fe-ettringite) was estimated through kinetic and equilibrium batch experiments. The As/Fe-ettringite formation was induced by injecting CaO and FeCl 3 into synthetic As(V) wastewater (1.33 mM). Different molar ratios of As(V)/Ca/Fe (1:2:1, 1:4:2, 1:6:3, 1:8:4, and 1:10:5) were experimented in batches, the ratio of 1:6:3 showed the best removal efficiency (%95%) among them. The control experiments in which CaO (8.008 mM) and FeCl 3 (4.004 mM) were used individually showed much lower arsenic removal capacities (2.5% for CaO and 32.5% for FeCl 3 ) compared with the combined system of CaO and FeCl 3 which led to As/Fe-ettringite formation. Equilibrium experiments were conducted in the pH range from 3 to 13, and the result showed As(V) removal by As/Feettringite formation was significant in the pH range from 10.9 to 11.8, which was favorable for the formation of ettringite phases. Well-crystalized As/Fe-ettringite was observed in the FE-SEM micrographs of samples, and the needle-like crystals were most abundant and clear in the sample taken at pH of 12.

show abstract

The evolution of structural changes in ettringite during thermal decomposition

Cited by 51 publications

References 23 publications

Effect of pressure on the crystal structure of ettringite

Effect of pressure on the crystal structure of ettringite

Calcium Sulfoaluminate, Geopolymeric, and Cementitious Mortars for Structural Applications

Development of a novel process for arsenic(V) removal from water using Fe-ettringite

Contact Info

Product

Resources

About