Alkali activated class C fly ash cement
US5565028A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 1, 1995 |
| Grant date | Oct 15, 1996 |
| Priority date | — |
| Expiry date | Jun 1, 2015 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/49
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Class C fly ash may be activated with strong alkali to yield a novel, dense, quick-setting cement having unexpected properties. The setting time of the cement decreased as the pH of the activating solution increased. The microstructure and phase assemblage of the novel cement depended on the pH. Ettringite was absent beyond pH 14.30 (2.0N); a hexagonal plate-like crystalline form (stratlingite (gehlenite hydrate, C.sub.2 ASH.sub.8) and other compounds) became more abundant at higher pH. At higher pH the microstructure was characterized by high amounts of the plate-like crystalline phase and a dense matrix, due to higher reactivity of the glassy phase in fly ash. The novel cement will have uses in a number of areas, including fixation of hazardous wastes such as radioactive wastes, applications where rapid setting is desired, and formation of concrete in hot environments where ordinary Portland cements may tend to crack due to their heat of hydration.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.