| 摘要 |
A cement composition is provided containing portland cement; calcium sulfate hemihydrate; urea; one or more retarders selected from the group consisting of a water soluble salt of a lignosulfonic acid, a low molecular weight hydroxypolycarboxylic acid and sodium, potassium, and lithium salts thereof, and an alkaline hexametaphosphate; and as optional ingredients, calcium chloride and/or a condensation product of mononaphthalene sulfonic acid and formaldehyde; said ingredients being present in amounts effective to provide a cement which will set within a desired period of time at temperatures below about 80 DEG F down to below freezing, e.g. 32 DEG F, to provide a monolithic mass having adequate strength and which also has a sufficient pumping time, i.e., setting time, at higher temperatures, i.e., above about 80 DEG F, so that it can be transported, i.e., pumped at such elevated temperatures without prematurely setting up.
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