| 摘要 |
<p>A cement retarder is provided which comprises 5 to 20% by weight, based on the weight of said retarder, of gluconic acid and/or tartaric acid and/or a water soluble salt thereof, 30 to 10% by weight, based on the weight of said retarder, of citric acid and/or an alkali salt thereof, and 50 to 85% by weight, based on the weight of said retarder, of an alkali carbonate. A rapid hardening cement is also provided which contains the above cement retarder.</p> |
