A flexible pavement structure comprises a surface layer, a base layer, a sub-base layer, and a subgrade layer. Herein, the surface layer is adjacent to and above the base layer, and the sub-base layer is adjacent to and above the subgrade layer. The flexible pavement structure further comprises a layered system composed of first, second, and third materials different from each other, and is disposed as an interface layer between the base layer and the sub-base layer. The first material is a geotextile fabric selected from a group consisting of polypropylene and polyethylene, providing ground stabilization or reinforcement properties. The second material is a waterproof heat insulation material selected from a group consisting of cross-linked polyethylene foam and laminated aluminum foil, providing waterproofing or impermeability properties. The third material is a glass foamed insulation material.