Cement treated with high-pressure CO.sub.2
US5650562A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 5, 1996 |
| Grant date | Jul 22, 1997 |
| Priority date | — |
| Expiry date | Apr 5, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S264/43
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Cured cement matrices are exposed to dense-phase or supercritical CO.sub.2 which enters the matrix through passages therein to neutralize the natural alkalinity of the cement so that alkali-intolerant materials can be incorporated in the cement. The CO.sub.2 converts calcium hydroxide in the cement to calcium carbonate and water, and the high pressure of the dense-phase or supercritical CO.sub.2 forms rounded, closely packed and aligned crystals with few or no visible pores or capillaries to enhance the homogeneity and strength of the cured cement and its bonding with, for example, uncoated reinforcing glass fibers. The supercritical CO.sub.2 can be used to transport other organic or inorganic materials, including pulverized metal, in solution or suspension into the interior of the cement matrix to alter its chemical and/or physical characteristics. The supercritical CO.sub.2 can further be used to quickly determine if a particular cement specimen comes from a wet cement mix to which a material has been added which prevents or hinders cement carbonation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.