PURPOSE: To aim at eliminating cracks and pits by laying a material in which sand added with no water and cement are kneaded at a predetermined ratio, over aluminum chips, and further by laying a wire gauze between the aluminum bed and road heating pipes.

CONSTITUTION: A material 1 in which sand and gravel are mixed is laid on aluminum chips 2, and a 150mm wire gauze 3 is laid thereover. Then, a cure rack 2 and pipes are laid thereover, and further, it is covered with a lath wire gauze 5. A material 6 in which sand and cement are kneaded at a ratio of 3:1 is laid over the lath wire gauze 5, and a surface finishing material such as asphalt, tiles or the like is laid thereover. With this arrangement, it is possible to eliminate cracks and pits.