Geotextiles in Pavement and Drainage Applications

The use of geotextiles in roads and highways is growing, especially in India, as infrastructure spending rises. Geotextiles are used across many engineering sectors: erosion control on slopes and embankments, rockfall protection, coastal and shoreline protection, road stabilisation, railway ballast and agriculture. This post covers their use in pavements and drainage.

What are Geotextiles?

Geotextiles are permeable fabrics made mostly from polypropylene or polyester, with polyethylene and polyamide used less often. Their physical properties can be adjusted for the project through additives and through the manufacturing method (woven, nonwoven or knitted). Their main functions are separation, filtration, stabilisation, reinforcement and drainage.

Woven and nonwoven geotextiles are both used in pavements and drainage. The properties that matter are resistance to installation damage, tensile strength, long-term durability when buried, and the range of thicknesses and strengths available.

Geotextiles in Pavement and Drainage Applications

The most common applications of geotextiles in pavements and drainage are:

• Reinforcement of pavement layers
• Rehabilitation of old pavement surfaces, crack treatment and spot repairs
• Encapsulation and separation
• Drainage, water control, prevention of clogging, and moisture control

For Pavements:

Geotextiles are widely used in asphalt overlays on roads and for separation and stabilisation of road bases. In an overlay, a paving fabric saturated with bitumen tack coat is laid between the old pavement and the new overlay. It acts as a stress-relieving interlayer that slows reflective cracking, and as a moisture barrier. As a separator, a geotextile between a soft subgrade and the granular layer above keeps the two from mixing.

For Drainage:

Good drainage relieves hydrostatic pressure, keeps the soil from losing strength and keeps the structure stable. Cracked pavements let surface water seep through to the subsoil. Water trapped between the subsoil and the pavement is then pumped out under traffic, carrying fines with it, which weakens the support under the pavement.

Geotextiles have been used in drainage since the 1970s. In drainage the geotextile either filters, letting water into a drain while holding soil back, or carries the water within its own plane. In pavement underdrains, the gravel-filled trench is wrapped in geotextile so water can enter the trench while the surrounding soil stays out and does not clog the gravel. Needle-punched nonwoven geotextiles are the usual choice here, because their pore size can be matched to the soil and they pass water easily.

Laid between the pavement layers and the subsoil, a thick nonwoven geotextile also works as a horizontal drainage layer, carrying water away before it can weaken the road structure.

Ocean Geosynthetics for Geotextiles:

In pavement construction, geosynthetics perform separation, reinforcement, filtration and drainage. Ocean Geosynthetics supplies woven and non-woven geotextiles along with other geosynthetic products. For a road example, see the Ocean Geotextile 150 GSM road project in Reasi, Jammu & Kashmir. Contact our team to choose the right geotextile for your project.