Abstract: A composition obtained by mixing together an aqueous solution or suspension of an ammonium or alkali metal borate and an organic polyisocyanate, and allowing the mixture to set.

Abstract: Cement compositions setting readily at temperatures below 0.degree. C are disclosed which are prepared by mixing together and allowing to cure a hydraulic cement, an inert filler, an organic polyisocyanate, water and coal tar. The organic polyisocyanate is used in an amount to provide an excess of isocyanate groups over the isocyanate-reactive groups contained in the coal tar itself; the weight of organic polyisocyanate and coal tar, taken together, is at least equal to the weight of the water used. Such compositions, improved by the addition of coal tar, exhibit advantages over conventional cement mixes and known urethane, epoxy and polyester resin-containing concretes.