Heat-insulating panel serving as concrete form and method of manufacturing the same

A method of manufacturing a heat-insulating panel serving as a concrete frame comprising the steps of:

• preparing contracted pieces having lengths of 20 mm or less of magnetic tapes, such as video tapes or cassette tapes, said cut or shredded pieces containing those having lengths from 5 to 20 mm in an amount of 50% or more on the basis of the total tape weight;
• adding 10 to 50 parts by weight of a thermosetting resin binder to 100 parts by weight of said contracted pieces of magnetic tapes, said binder comprising a material capable of becoming hard and molded by heating, at least one selected from the group consisting of phenol resin, urea resin, polyester resin, polyurethane resin, epoxy resin or melamine resin;
• and
• compression-molding said contracted pieces of magnetic tapes added with said binder under a pressure from 2 to 20 kgf/cm.sup.2 at a temperature from 100.degree. to 200.degree. C.