Double layer high strength concrete pipe
Abstract
Abstract A reinforced concrete pipe having an inner layer and an outer layer, said outer layer comprising Portland cement and said inner layer comprising a blend of a cement expanding agent and Portland cement in a proportion of from 4:96 to 20:80 by weight, said cement expanding agent comprising a pulverized, sintered material having a molar CaO/A12O3 ratio of 2/6 and a molar CaSO4/A12O3 ratio of 2/4, said pulverized, sintered material having a grain size distribution of particles of less than 44 microns representing less than 10 percent, particles of 44-250 microns representing more than 70 percent and particles of more than 250 microns representing less than 20 percent. A method of making a high strength reinforced concrete pipe, which comprises molding a reinforced concrete pipe having the above-noted composition, curing until said pipe has a strength sufficient to resist the mold releasing, releasing said pipe from the mold and subjecting said pipe to curing.
Inventors
- 👤 Yoshizo Ono
- 👤 Satoru Furui
Bibliographic Details
Claims Analysis
Total Claims: 2References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |