Abstract: The method of the invention comprises the steps of: a) employing expanded polystyrene portions of small dimension; b) subjecting said portions to milling until a grain size defining a fine micro-particles powder is obtained; c) placing said powder material into proper containers and immersing them into an aqueous solution comprising a fluidizer and a fire resistant product; d) processing the mixture for about 24 h using a stirrer until the saturation point is reached; e) filtering the obtained solution for draining the excess; f) employing the expanded polystyrene saturated solution obtained in the preceding steps as part of a mortar, using a stirrer and adding the required amount of water; g) pouring the uniform and viscous mixture obtained in the above step into molds giving the definite shape to each plate, into which molds setting and solidification drying is produced.