Foamed concretes are free flowing material. It is ideal for a wide range of applications. It is made by adding special foam to cement mortar slurry. It is a highly concentrated, highly efficient, low dosage liquid, which is fed with water into a foam generator. It has excellent water and frost resistance and provides a high level of both sound and thermal insulation. The foamed concrete formed is very stable and lightweight, and will not sink into soft ground or impose undue loading on roofs and other structures.

Polyisocyanate-based foams having a uniformly fine cell size are prepared by reacting a polyisocyanate with an isocyanate-reactive compound in the presence of a blowing agent mixture comprising a hydrocarbon component which has four or more carbon atoms and a polyfluorocarbon component which has a boiling point of from about 283 K. to about 393 K. at 760 mm Hg and wherein the boiling point:molecular weight ratio of said polyfluorocarbon component is less than or equal to 1.7. The hydrocarbon component is present in from about 5 to about 95 mole percent and the polyfluorocarbon in from about 95 to about 5 mole percent based on total amounts of hydrocarbon and polyfluorocarbon.Foaming system for closed-cell rigid polymer foam is as follows. This invention relates to the use of a C.sub.2-6 polyfluorocarbon compound containing no chlorine or bromine atoms as physical blowing agent in the preparation of rigid, closed-cell, polymer foams. Use of such blowing agents, especially 1,1,1,2-tetrafluoroethane (R-134a), in the preparation of polyurethane or polyisocyanurate foams provided for products in which the loss in thermal insulation performance with time compared to products prepared in absence of such blowing agents is reduced.