Geotextile synthetic materials, often referred to as ‘plastic mesh’, have many advantages over earlier fabrics. They are usually made of high-strength filaments encased in a polyolefin sheath in flat form, and are non-corrodible, lightweight and flexible. Plastic mesh structures can be used to stabilize and improve the load-bearing capacity of soft ground. These net structures allow free passage of water and do not clog. The mesh also acts as a load-distributing layer, thus reducing the stress in underlying weak soils.
Plastic mesh sheet has a basic advantage over solid materials when used as a horizontal sheet to improve the load-bearing capacity of natural soils. The solid materials, such as fibrous felt sheeting, caused problems due to the clogging of the sheet. This resulted in a build-up of pore water in the sheeting which in turn led to separation of the sheeting from the soil and the development of slip surfaces, which weakened the
ground structure. Polythene sheeting also causes water retention with resulting weakness due to the excess of
water in the ground above the sheeting. However, with the plastic mesh, or net, the water can drain through
the mesh and so avoid the clogging and weakening effect.
The mesh can be used to reduce the thickness of road construction required and allow traffic to use ground of
very low CBR value with a minimum of surface material. Care must, however, be taken to leave sufficient thicknesof material for frost protection, many low CBR sub-grades being frost susceptible. The mesh helps to produce a high-density, shearresistant layer of soil which distributes vertical loads and restrains soft ground in the lower layers of the sub-grade – it is reputed to make the soil more cohesive
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Plastic mesh used as shear resistant layer in soft ground
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