Phase composition of high strength binding material based on fine microspherical high-calcium fly ash

• Published in: Construction & building materials Vol. 216; pp. 525 - 530
• Main Authors: Sharonova, O.M., Kirilets, V.M., Yumashev, V.V., Solovyov, L.A., Anshits, A.G.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 20.08.2019; Reed Business Information, Inc. (US)
• Subjects: Coal fired power plants; Compressive strength; Crystalline hydrates; Fly ash; High-range water reducer; Hydrates; Hydration products; Thermal analysis; Water; X-ray diffraction; Fly ash; High-range water reducer; Hydration products; X-ray diffraction; Crystalline hydrates; Compressive strength; Thermal analysis
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.04.201

•The material with high early and long-term strength based on 100% industrial fly ash.•High hydration activity is ensured by high dispersion of the Ca-containing phases.•PC superplasticizer lowers water demand and greatly enhances compressive strength.•New phases are ettringite, calcium carboaluminate and calcium silicate hydrates.•The precursor of calcium hydrosilicates is the amorphous substance of microspheres. The combination of factors was established for using high-calcium fly ash (HCFA) as a binder material of high early and long-term strength: (1) high dispersity of microspherical HCFA, 90% <10 μm; (2) the positive effect of polycarboxylate superplasticizer, that allowed to use water / binder = 0.25; (3) formation of finely mixed hydrate phases such as portlandite, ettringite, calcium carboaluminate hydrates and cryptocrystalline calcium hydrosilicates. X-ray powder diffraction quantitative phase analysis of initial HCFA and hydration products in high-strength specimens was performed, which contributes to understanding phase transformations of HCFA during hydration and to improving the properties of the binder.