US4105459A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Siliceous ashes and hydraulic cements prepared therefrom
Assignee: University of California, San Diego
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Filing: 1975-12-15
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Granted: 1978-08-08
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Expires: 1995-12-15
Abstract
Abstract Siliceous compositions are prepared from naturally occurring plant materials (particularly rice hulls and rice straw) which have relatively high silica concentration by controlled incineration of the plant material to preserve the original cellular structure of the material and to prevent formation of crystalline forms of silica so that the silica in the product (which may contain from about 49% to about 98% silica remains in the amorphous state; the novel silica containing compositions find utility as a constituent of novel hydraulic cement compositions of high strength and acid resistance, useful in the preparation of mortar and concrete.
Inventors
- 👤 Povinder K. Mehta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 17:59
CPC Classifications
C; C04; C04B; C04B7/00
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
135 words
A relatively anhydrous composition comprising from 10 - 50% by weight of portland cement, said portland cement having from about 60 to 69% by weight of combined and uncombined CaO; and from about 32 to about 90% by weight of SiO 2 in the form of a highly reactive, amorphous anhydrous silica material derived from organic agricultural matter, having an initial silica content expressed as SiO 2 of up to about 28%, said silica material comprising from about 49 to about 98% SiO 2 , characterized by complete absence of crystalline silica as determined by x-ray diffraction analysis; balance being minor impurities and residual carbon, said carbon removable upon prolonged heating to give a composition containing from about 0.3 to about 2% residual carbon, and from 1.0 to about 5% minor impurities, other than CaO.
Claim 2
Dependent Claim
135 words
A relatively anhydrous composition comprising from 10 - 50% by weight of portland cement, said portland cement having from about 60 to 69% by weight of combined and uncombined CaO; and from about 32 to about 90% by weight of SiO 2 in the form of a highly reactive, amorphous anhydrous silica material derived from organic agricultural matter, having an initial silica content expressed as SiO 2 of up to about 28%, said silica material comprising from about 49 to about 98% SiO 2 , characterized by complete absence of crystalline silica as determined by x-ray diffraction analysis; balance being minor impurities and residual carbon, said carbon removable upon prolonged heating to give a composition containing from about 0.3 to about 2% residual carbon, and from 1.0 to about 5% minor impurities, other than CaO.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-08-07 | 1982-02-06 | 1982-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-08-07 | 1986-02-06 | 1986-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-08-07 | 1990-02-06 | 1990-08-08 | $7700.00 | Window Closed / Lapsed |