How Ocean Biaxial Geogrid 30 kN Strengthened a Reliance Project in Vijayawada, A Detailed Case Study

Introduction

At a Reliance project in Vijayawada, Andhra Pradesh, the engineering team needed to stabilise weak subgrade soil in a flood-prone part of the Krishna basin without adding to the schedule or to long-term maintenance. Ocean Non Wovens supplied 1,950 SQM of Ocean Biaxial Geogrid 30 kN for subgrade reinforcement.

This case study covers the product, the site conditions, how the geogrid was installed and checked, and what governs its long-term performance. Ocean Non Wovens manufactures and supplies geosynthetics across India.

Project overview

Project specifications and scope

The project required ground stabilisation and subgrade reinforcement across a designated industrial zone. The material had to carry heavy static and dynamic loads and cope with monsoon flooding, high humidity and the saline groundwater found in coastal Andhra Pradesh.

• Project Name: Reliance Project
• Location: Vijayawada, Andhra Pradesh
• Product Supplied: Ocean Biaxial Geogrid 30 kN
• Quantity Deployed: 1,950 SQM
• Supplier: Ocean Non Wovens (Geosynthetics Manufacturer, India)
• Application: Subgrade stabilization, load distribution, and long-term soil reinforcement for industrial infrastructure

Why a biaxial geogrid

The project engineers considered several soil reinforcement options, including thicker granular fill, geocells and uniaxial geogrids. They chose the PP biaxial geogrid 30 kN for its equal tensile strength in the machine and cross-machine directions and its resistance to the saline and acidic conditions found in local soils. IRC SP:59-2019, the Indian Roads Congress guideline on geosynthetics in road pavements, covers geogrid reinforcement of base and sub-base layers.

Technical profile: Ocean Biaxial Geogrid 30 kN

Product specifications

The Ocean Biaxial Geogrid 30 kN is an extruded polypropylene grid. The values below are from Ocean’s published data for its PP biaxial 30 kN grade (OG/GG PP-3030), tested to ASTM D6637 / EN ISO 10319:

• Material: Polypropylene (PP), extruded
• Type: Biaxial Geogrid
• Ultimate Tensile Strength (MD): 30 kN/m
• Ultimate Tensile Strength (CD): 30 kN/m
• Tensile Strength at 2% Strain: 10.0 kN/m in each direction
• Tensile Strength at 5% Strain: 20 kN/m in each direction
• Aperture Size: 38 mm (±5 mm); a 60 mm aperture variant (PP-3030L) is also made
• Chemical Resistance: Polypropylene resists the acids and alkalis found in natural soils; resistance to specific liquids is evaluated with ASTM D5322 immersion procedures

The strength at 2% and 5% strain matters more than the ultimate value for subgrade work, because a stabilised base deforms only a few per cent in service. The grid has to develop its load at those small strains.

Biaxial or uniaxial

Uniaxial geogrids carry strength along one axis, which suits retaining walls and steep slopes where the force acts in one direction. Under an industrial pavement, wheel and equipment loads spread in all directions, so a grid with equal strength along and across the roll is the usual choice for base stabilisation.

Site conditions in Vijayawada

Black cotton soil and a high water table

Vijayawada sits on the Krishna River at the head of its delta. Parts of the region have expansive black cotton soil (vertisol) with high plasticity and soaked CBR values that are often below 3%. The soil swells when wet and shrinks when dry, which puts cyclical stress on anything built on it. In parts of the delta the water table lies within 1.5 to 2 meters of the surface, which adds to the risk of subgrade failure. The biaxial geogrid spreads wheel and equipment loads over a wider area of the weak subgrade, lowering the stress any one point of soil carries.

Flooding and the monsoon

Vijayawada receives an average annual rainfall of approximately 1,040 mm, most of it during the southwest monsoon (June to September), and the lower Krishna basin floods regularly. Reinforcement here has to keep working when saturated or submerged. Polypropylene does not absorb water, so the grid’s tensile strength is not reduced by waterlogging.

Salinity

Vijayawada is approximately 70 km inland from the Bay of Bengal, and groundwater in the delta can carry high salinity and chloride levels. Steel reinforcement corrodes in these conditions; polypropylene does not. The same resistance makes PP geogrids suitable for aquaculture pond embankments and other water-side structures in coastal Andhra Pradesh.

Other applications of the same grid

Industrial plant foundations

Heavy equipment pads, storage tank foundations and access roads need consistent bearing capacity. A biaxial geogrid at the base of the granular layer creates a mechanically stabilised layer: aggregate locks into the apertures, cannot spread sideways under load, and the stiffer layer reduces differential settlement. Designers often use that stiffness to reduce the base course thickness needed over weak subgrade.

Aquaculture pond embankments

Andhra Pradesh is India’s largest aquaculture-producing state, particularly for farmed shrimp. Pond embankments there face hydrostatic pressure, wave action and erosion from saline water. Biaxial geogrids reinforce embankment fill and help prevent slope failures.

Marine and water containment works

Geogrids are used in breakwater foundations, jetty approach roads and coastal revetments, and in the structural layers beneath geomembrane-lined ponds, where a stiffer foundation reduces differential settlement under the liner.

Environmental protection

Landfill capping, effluent treatment ponds and riverbank erosion control also use biaxial geogrids. Near sensitive areas such as the Krishna delta, stabilised ground reduces soil displacement and the sediment that washes into watercourses, which supports the environmental conditions large projects carry under India’s Environmental Impact Assessment (EIA) notification.

Installation and quality control at the Reliance site

Step-by-step execution

The installation of 1,950 SQM of Ocean Biaxial Geogrid 30 kN followed this sequence:

1. Site survey and subgrade assessment: Soil samples were tested for CBR, moisture content and plasticity index. Areas with CBR below 3% were flagged for geogrid reinforcement.
2. Subgrade preparation: The native soil was graded, cleared of debris and compacted to 95% Modified Proctor Density to give a uniform base.
3. Geogrid deployment: Rolls were laid flat with a minimum overlap of 300 mm at all panel joints, oriented so that both directions shared the tensile load.
4. Anchoring: Edges were secured with U-shaped steel pins at 1-meter intervals to stop the grid moving during aggregate placement.
5. Aggregate placement: Well-graded granular fill (25 to 50 mm nominal size) was spread over the geogrid to the specified thickness so that particles seated in the apertures.
6. Compaction: Vibratory rollers compacted the fill to target density, locking the aggregate into the grid.
7. Post-installation inspection: Field plate load tests and visual inspection checked load distribution and geogrid engagement.

Fill is pushed forward over the grid rather than tipped onto it, and tracked or wheeled plant should not run directly on the exposed geogrid.

QA/QC checks

Geogrid installations usually fail at the details: short overlaps that leave weak strips, aggregate too fine or too coarse to interlock, and poor compaction at corners and edges. At the Reliance project, Ocean Non Wovens’ technical team carried out these checks:

• Tensile verification testing: Random samples from delivered rolls were tested for tensile strength conformity per ASTM D6637.
• Overlap audits: Every panel joint was inspected and photographed to confirm the minimum 300 mm overlap.
• Aggregate gradation checks: Fill was tested to confirm its particle size distribution suited the geogrid’s aperture.
• Compaction density logging: Nuclear density gauge readings were taken at several points in every 100 SQM section to find under-compacted zones.

See more Ocean case studies.

Long-term performance

Durability in a hot, wet climate

Once buried, a geogrid is shielded from UV, which is the main threat to polypropylene during storage and installation. Rolls should be kept covered on site and the grid covered with fill promptly; UV resistance of geosynthetics is tested under ASTM D4355. Buried PP grids do not rot, corrode or support biological attack.

Maintenance

The reinforcement layer itself needs no maintenance. Unlike steel mesh, a PP geogrid does not corrode, needs no cathodic protection and does not lose cross-section. Maintenance focuses on the surface above it: watching for settlement or erosion, as with any engineered subgrade.

Cost

A geogrid adds a material cost at construction. It is usually justified by a thinner aggregate base, less imported stone and haulage, and fewer repairs over the pavement’s life. The balance depends on subgrade strength, traffic and aggregate prices, and is worked out in the pavement design for each project.

Frequently asked questions

What is Ocean Biaxial Geogrid 30 kN used for?

It is a polypropylene reinforcement grid used to stabilise subgrades, improve bearing capacity and spread loads under roads, railways, industrial foundations, aquaculture embankments and marine works. It has an ultimate tensile strength of 30 kN/m in both the machine and cross-machine directions.

How does a biaxial geogrid improve soil stability in industrial projects?

Compacted aggregate locks into the grid’s apertures. The grid stops the aggregate spreading sideways under load, so the base stays stiffer, spreads load over a wider area of subgrade and settles less unevenly. That matters under heavy equipment foundations and access roads.

Can biaxial geogrids be used in flood-prone and saline environments?

Yes. Polypropylene does not absorb water or corrode, so the grid keeps its tensile performance when waterlogged, submerged or in saline ground. That makes it suitable for coastal Andhra Pradesh, aquaculture zones and flood-affected areas such as the Krishna basin. For aggressive industrial liquids, check compatibility with immersion testing per ASTM D5322.

How long do PP biaxial geogrids last?

Buried and protected from UV, polypropylene grids do not rot, corrode or degrade biologically. Design life for a particular application is set by the designer using reduction factors for installation damage, creep and durability.

What is the difference between uniaxial and biaxial geogrid?

Uniaxial geogrids have high tensile strength in one direction and suit retaining walls and steep slopes. Biaxial geogrids have equal strength in both directions and suit road bases, industrial foundations and embankments where loads spread both ways.

Ocean Non Wovens

Ocean Non Wovens manufactures and supplies geosynthetics for roads, railways, industrial projects, aquaculture, marine works and environmental protection, from 1,950 SQM installations like this one to 80,000+ SQM railway corridors. To discuss a project, contact Ocean Non Wovens at www.oceangeosynthetics.com.