| 摘要 |
The rate of hardening of a portland cement mix is accelerated by the addition of a low molecular weight, water-soluble hydroxylated adduct formed by reacting melamine and an aldehyde. The adduct is employed in an amount within the range of from about 0.01% to about 1.00%, preferably from about 0.2% to about 0.8% by weight of cement. The water content of the cement mix for a given consistency tends to be lowered by the incorporation of the adduct, providing an additional advantage from the practice of the invention. The adduct may be employed as a concentrated solution in water and may be used in combination with known set accelerating agents and with set retarding agents where reduction in water content is desired without appreciable change in the rate of set of the cement mix.
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