Abstract: Polymer-based composite materials comprising a polymer, such as high density polyethylene, and one or more functional fillers, such as powdered metals, carbon, or ceramics, are described. The composite materials can be used for concrete forming applications. For example, the polymer-based composite materials can be formed into sheets and laminated onto various non-metal substrates, such as plywood, for use as concrete pouring forms. The polymer-based composite materials can also be used as facings and liners for metal concrete pouring forms. The forms can be used multiple times without release agents and without staining or physically damaging the cured concrete. The polymer-based composite materials can be provided with various surface textures, patterns, and designs. Methods for bonding the polymer-based composite materials to various non-metal and metal substrates are also described.