US3573940A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fly ash based preformed support structures
Assignee: United States Department of the Interior
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Filing: 1969-01-31
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Granted: 1971-04-06
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Expires: 1989-01-31
Abstract
Abstract A PROCESS OF MAKING A PREFORMED SUPPORT STRUCTURE, SUCH AS BRICK, COMPRISING ADMIXING FLY ASH, A COARSE AGGREGATE, SODIUM SILICATE, AND HYDROCHLORIC ACID; SHAPING UNDER PRESSURE; DRYING AND FIRING AT ELEVATED TEMPERATURES.
Inventors
- 👤 Charles F Cockrell
- 👤 Harry E Shafer Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:56
CPC Classifications
C; C04; C04B; C04B18/00; C04B18/04; C04B18/06; C04B18/08; C04B28/00; C04B28/24; C04B28/26; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/91
Claims Analysis
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |