Filtration and separation in the foundation of an airport runway

Geodren® PPST for Kolkata airport runway

Geodren® PPST: nonwoven geotextile in the foundation of an airport runway.

Problem

In the airport sector, one of the most common situations is the extension of runways or aircraft parking areas. From a technical standpoint, there is an extremely wide range of geosynthetic solutions to guarantee safety and durability for this type of work. At Kolkata airport, the subgrade was made up of mixed materials (clays and sands) with good compression resistance.

The main problem was the drainage of rainwater resulting from the monsoon climate. At the same time, it was necessary to minimize the erosive effect of water flows beneath the pavement. In addition, the chosen material had to guarantee that performance levels would be maintained over time.

Solution

Engineers chose to use Geodren® PPST 450, a nonwoven geotextile capable of simultaneously performing separation, filtration and drainage functions. To achieve particularly high permeability performance on the geotextile plane, a mix of fibers with a specific linear density was used. This achieved a considerable increase in the drainage capacity of Geodren® PPST 450. In addition, the thicker fibers ensure greater durability, both in terms of chemical aging and microbiological resistance.

Geodren® PPST 450 was installed on top of the in-situ soil, made up mainly of clay and sand. On top of it, 10 cm of sand and 30 cm of clayey soil were laid. A drainage pipe was placed every 20 meters to facilitate the evacuation of the large water flow that occurs during monsoon rainfall. The various geotextile sheets were joined by fusing the outer edges, with an overlap of about 10 cm.