Backing materials of carpets include asphalt type and polyvinyl chloride resin type materials. Asphalt type materials involve problems that give an offensive odor, become stiff in the winter, and, in high temperatures, are softened to contaminate the surroundings or undergo thermal deterioration. Polyvinyl chloride resin type materials involve an environmental problem that harmful chlorine gas is given off on combustion of disposing them.
In order to overcome these problems of the conventional carpet backing materials, it has been proposed to use a sheet formed from a composition comprising cement and a thermoplastic resin emulsion, which is adhered to the reverse side of carpeting surface base material with an adhesive, as disclosed in JP-B-60-58347 (the term "JP-B" as used herein means an "examined published Japanese patent application"). According to this method, since the cement becomes brittle if abruptly exposed to a high temperature, the sheet must be harden and dried slowly enough, resulting in poor productivity. Moreover, the resulting carpet is too hard and lacks flexibility.