| 摘要 |
PCT No. PCT/GB94/01603 Sec. 371 Date Apr. 10, 1996 Sec. 102(e) Date Apr. 10, 1996 PCT Filed Jul. 26, 1994 PCT Pub. No. WO95/04190 PCT Pub. Date Feb. 9, 1995A highway pavement has a multi-layer structure (20) interposed between the subbase (24) and the subgrade (22). The multi-layer structure is also suitable for use in railway pavements. The multi-layer structure (20) comprises upper and lower flexible sheet materials (14; 10) and an intermediate load-spreading layer formed of a multiplicity of load-spreading elements (12) held together in the desired preset relationship so that gaps are provided between adjacent elements (12) for passage of water. The upper flexible sheet material (14) is water permeable. The lower flexible sheet material (10) is either (a) substantially water impermeable but provided with perforations (16) or slits therethrough at locations which open into the gaps between the load-spreading elements (12), or (b) water vapour permeable but substantially impermeable to liquid water, or (c) substantially impermeable to liquid water and water vapour. In some embodiments the upper sheet material (14) may be omitted. |
