| 摘要 |
PROBLEM TO BE SOLVED: To improve shear tightening strength between a polyethylene layer and a mortar layer, by forming helical protuberance on the surface of the polyethylene layer, in a heavy corrosion protective covering steel pipe in which a polyethylene adhesives layer and a polyethylene layer are sequentially laminated via a primer layer coated on a surface of a preserved steel pipe. SOLUTION: In a polyethylene covering steel pipe which is used in a variety of buried pipes and a steel pipe pile, a primer layer 2, a polyethylene adhesive layer 3, and a polyethylene layer 4 are sequentially laminated on an outer surface of a preprocesses steel pipe 1 or a steel pipe pile 1, and then a fiber reinforced plastics layer 6 or a mortar layer 6 are laminated. On the outer layer of the polyethylene layer 4, helical protuberance 5 which is 0.1-5 mm high and 3-100 mm wide is formed, in order to improve shear tightening strength between the polyethylene layer 4 and the laminated fiber reinforced plastic or mortar. When it is necessary to color the coating for harmony with environment, a color pigment is previously mixed and the fiber reinforced plastic layer 6 or the mortar layer 6 is colored. |
