| 摘要 |
PCT No. PCT/GB89/01078 Sec. 371 Date Jul. 18, 1990 Sec. 102(e) Date Jul. 18, 1990 PCT Filed Sep. 14, 1989 PCT Pub. No. WO90/03346 PCT Pub. Date Apr. 5, 1990.A hardened cement is prepared by mixing together two slurries, one comprising water and a cement component and the other comprising water, beta anhydrite and calcium oxide and or calcium hydroxide. According to the invention the cement component of the first slurry comprises ferrite and C12A7 or A7 A-CX2 (where X is a halogen atom) and a reactive source of silica.
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