| 摘要 |
PCT No. PCT/FR90/00099 Sec. 371 Date Oct. 11, 1991 Sec. 102(e) Date Oct. 11, 1991 PCT Filed Feb. 12, 1990 PCT Pub. No. WO90/09357 PCT Pub. Date Aug. 23, 1990.This invention relates to a lightened gas-impermeable cement grout which comprises hydraulic cement, water, silica fumes in an amount of from about 5 to about 65 weight % based on the weight of the cement, and at least one polyethylene imine having a molecular weight of between about 600,000 and about 1,000,000 in an amount of from about 1 to about 25% weight % based on the weight of the water.
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