| 摘要 |
1,190,903. Water-repellent cements. DYCKERHOFF ZEMENTWERKE A.G. 8 Jan., 1969 [8 Jan., 1968], No. 1139/69. Heading C1H. Portland cement for stabilizing sandy or cohesive soils is rendered water-repellent by the addition, before or after grinding, of 0À05 to 2 wt. per cent of a predominantly tertiary saturated monocarboxylic acid having from 5 to 20 carbon atoms in the molecule. 0À05 to 0À5 wt. per cent of a paraffin oil or wax can be included as an antidusting agent. A suitable mixture of acids is prepared from olefins, water and carbon monoxide under the action of strong acids and contains 90% of tertiary acids of the formula R 1 (R 2 )(R 3 ).C.CO 2 H, where R 1 , R 2 and R 3 are unbranched alkyl radicals and at least one of these is a methyl group, and 10% of acids containing a secondary carboxyl group. A minor proportion of the tertiary acids can have cyclic structures with 5-membered hydrocarbon rings.
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