A 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.
|Patent number||US 5823706 A|
|Publication status||Published - 20 Oct 1994|