NHAI Infrastructure Development with Ocean Geocomposite in Patna, Bihar

Ocean Non Wovens supplied 3,000 SQM of Ocean Geocomposite to a National Highways Authority of India (NHAI) project in Patna, Bihar. The material went beneath the pavement layers to deal with two problems common on Bihar’s highways: weak alluvial subgrade and water getting into the pavement.

What a geocomposite does in a road

A geocomposite combines two or more geosynthetics in one product. The type used here pairs a geotextile for filtration and separation with a geogrid for reinforcement, so a single layer does several jobs:

• Soil stabilization: spreads wheel loads over a wider area of subgrade, reducing settlement.
• Drainage and filtration: lets water pass while holding soil particles back, so water does not collect in the base.
• Erosion control: on embankments and slopes, helps hold surface soil in place.
• Reinforcement: the geogrid interlocks with the aggregate and restrains it laterally, which reduces rutting and cracking.

In India, IRC SP:59 (guidelines for geosynthetics in road pavements) and MoRTH Specifications Section 700 cover the use of geosynthetics in highway works.

Site challenges in Patna

Patna lies on the Gangetic plain, and traffic on its roads is growing with the city. The project faced:

1. Weak soil subgrade: Bihar’s alluvial soils are often silty and clayey and lose strength when wet, so the road needed reinforcement to prevent deformation.
2. Heavy rainfall and drainage issues: high moisture content in the soil had led to frequent pavement failures.
3. Increased traffic load: the road needed to carry growing vehicle loads.

How the geocomposite was used

The Ocean Geocomposite was placed beneath the pavement layers. Its geotextile component filters and separates, stopping fine soil from migrating up into the base layer when the subgrade is wet and loaded. The geogrid component spreads the load and confines the aggregate above it.

A layer like this is expected to deliver:

• Longer pavement life: a reinforced, clean base resists rutting and cracking better than an unreinforced one on the same soil.
• Lower lifecycle cost: fewer repairs and less frequent resurfacing.
• Better drainage: less water held in the pavement layers, so less moisture damage.
• Less material: reinforcement can reduce the granular thickness needed over weak soil, which saves quarried aggregate and haulage.

For good results, the subgrade should be trimmed and compacted before laying, rolls should overlap at the specified width, and the first lift of aggregate should be spread from the end of the placed material instead of by driving directly on the geocomposite.

Geosynthetics used on Indian highways

1. Geotextiles: separation, filtration and drainage.
2. Geogrids: reinforcement over weak subgrades and in reinforced soil walls.
3. Geomembranes: waterproofing.
4. Geocells: load distribution and slope erosion control.
5. Geocomposites: reinforcement plus separation or drainage in one layer, as on this project.

Ocean Non Wovens manufactures and supplies geosynthetics for highways, railways and embankments across India. For a similar application, see Ocean Geocomposite 710 GSM on an NHAI project in Madhya Pradesh, or browse more case studies.