Enhancing Road Infrastructure in Yadgir, Karnataka with Ocean LDPE Liner – 300 Micron

For a road project in Yadgir, Karnataka, Ocean Non Wovens supplied and installed 33,000 SQM of Ocean LDPE Liner – 300 Micron. The liner was laid over the compacted subgrade as a moisture barrier, to keep water out of the expansive black cotton soil beneath the road and protect the pavement above it. It is one of several geosynthetics used to deal with problem soils in road work.

Project Overview

• Location: Yadgir, Karnataka
• Product Used: Ocean LDPE Liner – 300 Micron
• Total Quantity Supplied: 33,000 SQM
• Purpose: Soil stabilisation, moisture barrier and subgrade protection beneath the road layers

The challenge: black cotton soil

Much of Yadgir district sits on black cotton soil, a clay that swells when wet and shrinks and cracks as it dries. A road built on it moves with the seasons, which leads to:

• Frequent cracking of the road surface
• Soft, unstable subgrade in the rainy season
• A shorter pavement life

The damage comes from changes in the soil’s moisture content. Keeping water from getting into the subgrade, and keeping its moisture steadier through the year, reduces the swelling and shrinking. That is the job the LDPE liner was brought in to do.

Why an LDPE liner in a road

Low-density polyethylene (LDPE) liners are flexible, lightweight geomembranes. At 300 micron (0.3 mm), the sheet is thin and pliable enough to lay quickly over large areas while still forming a continuous waterproof layer. Under a road it works as:

1. Moisture barrier: it cuts off water seeping down from above and limits capillary rise from below into the pavement layers.
2. Subgrade protection: a subgrade that stays drier keeps more of its strength and swells less.
3. Lower maintenance: fewer water-related failures mean fewer repairs.

The liner does not add structural strength; load is still carried by the granular and bituminous layers above it. The use of geosynthetics in road pavements, including on poor subgrades, is covered by IRC SP:59-2019 (Guidelines for Use of Geosynthetics in Road Pavements and Associated Works).

Why the 300 micron grade

The 300-micron thickness was chosen to balance strength and pliability for this project. The liner offers:

• Tensile strength to take the stresses of placing and compacting aggregate over it
• Chemical resistance: polyethylene is stable in acidic and alkaline soils
• UV stabilisation for the period it lies exposed during construction
• Easy installation: light rolls that a small crew can lay quickly

Installation sequence

1. Site preparation: the subgrade was levelled and compacted to remove undulations and sharp objects.
2. Liner deployment: the 300-micron LDPE liner was unrolled directly over the compacted subgrade.
3. Overlap and joining: adjacent sheets were overlapped by 150 mm and heat-welded for a watertight joint.
4. Cover layers: a non woven geotextile could be placed over the liner as a cushion where needed, followed by the GSB (granular sub-base) and the remaining road layers.

A thin liner needs a few precautions. Leave a little slack when laying so the sheet is not stretched tight as temperatures change, because polyethylene expands and contracts noticeably. Keep plant off the bare sheet and tip the first layer of GSB from the already-covered side. Collect offcuts and packaging and dispose of them properly rather than burying them in the fill.

What the liner does over the road’s life

With the subgrade sealed from seasonal water, a road on black cotton soil should see smaller moisture swings in the subgrade during the monsoon, less of the cracking and rutting typical of expansive clay, and fewer repairs. Prefabricated rolls also lay faster than most conventional moisture-control treatments.

Ocean Non Wovens supplies geomembranes and other geosynthetics for roads, reservoirs, landfills and railways across India, with technical support on site. More projects are on our case studies page.