Stabilising a Strategic Airbase: How Ocean HDPE Geocell 330 × 100 mm Reinforced the Air Force Project at Gwalior

Project snapshot

A defence facility near Gwalior, Madhya Pradesh, needed ground reinforcement that could carry heavy aircraft support traffic over poor subgrade. The engineering team specified a cellular confinement system instead of a conventional thick aggregate build-up, and Ocean Non Wovens supplied 7,000 square metres of Ocean HDPE Geocell in the 330 × 100 mm configuration for ground stabilisation and reinforcement. This case study covers why a geocell suited the site, how it works under load, and what has to go right during installation.

Geosynthetics in defence infrastructure

Defence works combine heavy loads, tight timelines and very little tolerance for later failure. Runways, aircraft parking aprons, hardstands, blast pads and internal supply roads have to stay serviceable through decades of repeated dynamic loading, often on ground chosen for its strategic position rather than its soil.

Geosynthetics let designers improve the ground they have instead of excavating it and replacing it with imported stone. Geocells, geogrids and geotextiles each change how soil behaves under load, and on a programme with fixed deadlines, the reduced excavation and haulage can decide whether the work is deliverable at all.

What HDPE geocells are

An HDPE geocell is a three-dimensional honeycomb made from high-density polyethylene strips, ultrasonically welded together at regular intervals. The panel arrives collapsed; on site it is stretched open into a network of connected cells, which are then filled with granular material, sand or, in some cases, lean concrete. The Gwalior works used the 330 × 100 mm specification: a nominal welded cell dimension of about 330 mm and a cell wall height of 100 mm, a depth suited to load-bearing platforms under trafficked surfaces.

The working principle is cellular confinement. Loose aggregate has almost no tensile strength, so under a wheel load it spreads sideways and the surface ruts. Inside a geocell the aggregate cannot move laterally. The confined fill, the cell walls and the passive resistance of neighbouring cells act together as a semi-rigid mattress that spreads load far better than the same aggregate laid loose. ASTM D8269 (Standard Guide for the Use of Geocells in Geotechnical and Roadway Projects) describes these two mechanisms, lateral confinement and the mattress effect, and the strength of the welded junctions is tested to ISO 13426-1.

Why a geocell instead of conventional methods

The usual answers to weak subgrade are a much thicker granular layer or stabilisation with cement or concrete. Both work, and both have costs. A thicker aggregate section needs large volumes of quarried stone, long haulage and heavy compaction plant, which add cost, time and carbon. Concrete is durable but brittle: it cracks under differential settlement, and repairing a concrete platform on an operational base disrupts operations.

Cellular confinement sits between the two. A comparatively thin layer of good aggregate, confined in the Ocean HDPE Geocell, can carry load like a deeper unreinforced section. India’s IRC:SP:59 (Guidelines for Use of Geosynthetics in Road Pavements and Associated Works) covers geocells among the geosynthetics that can be used to strengthen pavement layers and improve weak subgrade.

The engineering challenges at Gwalior

Air Force infrastructure puts several hard problems in one place:

• Subgrade: parts of the site had weak, variable ground with a low California Bearing Ratio and poor support for any pavement laid directly on it.
• Loads: aircraft support equipment, tankers, fire tenders and laden defence vehicles apply much higher contact pressures than normal highway traffic.
• Repeated dynamic loading: the same loads applied again and again cause progressive deformation and fatigue.
• Differential settlement: uneven support shows up as cracks and steps in the finished surface.
• Drainage: water held in a confined platform softens the subgrade and speeds up failure.
• Timeline: as with most strategic works, the job had a strict schedule with no room to relax quality.

How Ocean HDPE Geocell 330 × 100 mm works under load

Under a wheel, the confined infill spreads the applied stress across a wide band of connected cells, so the pressure reaching the subgrade is lower and spread over a larger area. Lower vertical stress on the soil means higher effective bearing capacity for the platform.

Because the aggregate cannot migrate sideways, it stays at its compacted density, which resists the rutting that normally forms under channelised traffic. The mattress bridges local soft spots and evens out settlement. On exposed slopes and shoulders, the cells also hold surface material in place against erosion. Together, lateral restraint, load spreading and the reduced aggregate thickness give a more economical pavement than an unreinforced section of the same capacity, which is the soil reinforcement case for geocells.

Installation: where geocell projects succeed or fail

A geocell performs only as well as it is installed. The main points:

• Subgrade preparation: trim, proof-roll and get a uniform formation before laying panels. No product fixes an uneven base.
• Expansion and anchoring: open each panel to its full cell geometry and hold it with stakes or tendons so it does not spring back before filling.
• Infill quality: well-graded, angular aggregate confines better than rounded or dirty fill.
• Compaction: over-vibration can damage cell walls, while under-compaction leaves the mattress soft.
• Sequencing and drainage: fill should follow expansion in a controlled front, with drainage planned so water does not pond in the platform.
• Inspection: check weld integrity and cell dimensions as work proceeds.

The usual mistakes on geocell jobs are partial cell expansion, over-filling before compaction and skipped anchoring. These were specifically guarded against on the Gwalior works.

Long-term performance

Strategic assets are judged over decades. The main durability concern for polyethylene cell walls is slow crack growth under sustained stress, measured as environmental stress-crack resistance with the notched constant tensile load test, ASTM D5397. Carbon-black stabilisation protects the strips from UV during the period they are exposed in construction, and HDPE resists the fuels, salts and soil chemistry found around an airbase. A confined section fatigues more slowly under cyclic loading than unreinforced aggregate, which keeps maintenance down. Thinner sections, less haulage and a longer service life all reduce lifecycle cost.

Lower material use

A reduced aggregate thickness means less quarried stone, fewer truck movements and less diesel to haul it, which lowers the project’s carbon footprint. Faster placement shortens the construction window, and a longer pavement life means fewer rehabilitation cycles.

Other uses for HDPE geocells

The same confinement principle is used at airports and on military roads, in logistics yards and container terminals with severe point loads, under railways and highways, on temporary haul roads, in embankments, and for slope protection, retaining wall facings and canal lining. Where weak ground meets heavy or repeated load, cellular confinement is a faster and lighter alternative to deep excavation and replacement. For finer-grained subgrades, a non woven geotextile separator under the geocell keeps fines out of the infill.

Work with Ocean Non Wovens

Ocean Non Wovens manufactures and supplies geocells, geotextiles, geomembranes and related geosynthetics for defence infrastructure, airports, highways, railways, industrial developments and environmental works across India. If your project involves weak ground, heavy loading or a tight programme, our technical team can help you specify the right product and supply it at scale. See more projects in our case studies.