Methods and systems for processing waste materials and for manufacturing composite materials are disclosed herein. According to some embodiments, the heterogeneous waste includes a plastic component and a non-plastic component, and the non-plastic component includes a plurality of pieces of waste. The heterogeneous waste is heated to melt at least a portion of said plastic component and reducing a volume of said heterogeneous waste, and then mixed (e.g. by rotating a mixing chamber or by stirring) until at least some said pieces are each encapsulated by the melted plastic component. Upon cooling, the mixture optionally sets into a composite material. The presently disclosed invention does not require pre-sorting of the heterogeneous waste and is operative to process “as is” waste. Optionally, the waste is pre-sorted. Exemplary uses for the composite material include but are not limited to flooring sheets, construction bricks, thermal insulation, acoustic walls, road paving materials, road beds, ba
