Road connectivity is what has led to the growth of human civilisation. While many parts of the world remain unconnected, despite so many decades of progress, roads remain a subject of engineering challenges. A common problem faced by pavement engineers is the development of cracks in highways, roads, and pavements, which may compromise safety in addition to cost implications for maintenance. Geogrids – a class of geosynthetics – play a vital role in reducing cracking in new pavements and asphalt, delaying the onset of reflective cracking. They provide a stress relief layer and prevent or delay top down / bottom up cracks into the subbase and/or subgrade. Geosynthetics have been proven to enhance the performance and extend the service life of both paved and unpaved road systems. In India, geogrids have been used in highways, runways, hydro-projects, or ports have been in use for over 3 decades now. Some examples include:
In this blog, we explore the various factors contributing to road cracking and innovative solutions paving the way towards crack-free roads. As a starting point, geogrids in highways or roadways serve four main purposes: reinforcement for subgrade, minimising cracking, load transfer, and stress relief.
Cracks, rutting or potholes compromise the safety of the roads, making it essential to understand the typical causes behind them. Localised depression and settlement are also often caused by subgrades that face water saturation.
Road construction comes with a variety of civil engineering challenges for pavement design. Building highway networks that work across all types of soil types, subgrades, elevation, temperatures and rainfall levels requires resilient materials. India witnesses extreme temperatures across the length and breadth of its roadways.
Geogrids are made from durable materials such as polymers, and are designed for this purpose. Geogrids work to improve the effective CBR [California Bearing Ratio] value of subgrade principally, across a wide range of conditions. Depending on the class of geogrids –uniaxial and biaxial- types, geotextiles, or geocells different structural weaknesses can be addressed, from site to site. Right from mountains which can be prone to landslides, high traffic national highways to soft soil challenges at different sites –geogrids and geocomposites provide solutions for every single application. Be it asphalt highways, paved, or unpaved roads, longevity is a key consideration.
Geogrids –used as a reinforcement layer for subgrade –that work specifically on highway or road strength requirements by providing support and reinforcement to the foundation, making it more resilient against wear and tear. Be it steep slopes, clay soil, aggregate paved roads, embankments, bridges –geogrids allow for structural reinforcement.
In a high-traffic highway scenario, integrating geogrids as a fortification mechanism within the road structure plays a crucial role in efficiently distributing stress. The high-strength polymers of the geogrid interlock with the surrounding soil and rocks, forming a robust structure that resists deformation under heavy traffic loads. By enhancing soil confinement and reducing lateral movement of rocks, geogrids significantly bolster the road’s load-bearing capacity. Geogrids also protect against soil erosion by locking soil. This prevents the development of cracks and bumps that typically result from prolonged exposure to substantial loads. This is not just limited to new installations, but equally useful to repairs for highway lanes and isolated crack repairs also.
Since geogrids are made from polymers, they work across a variety of terrains. Thus, allowing for maximum land utilisation by improving soil stability and cohesion. A common application is placing it within the layers under the paved road surface to provide reinforcement and distribute loads more effectively. For example, SGB [StrataGrid BiaxialTM ] biaxial Geogrid is strategically placed within the pavement, countering vertical loads from vehicular traffic and generating horizontal forces in the granular layers. Supported by the geogrid, the granular sub-base plays a vital role in distributing loads and providing structural support, while the natural ground forms the base layer. The SGB Geogrid serves as a reinforcement mechanism, significantly enhancing the overall load-bearing capacity of the pavement structure.
Geogrids are particularly useful which have a weak load bearing capacity By reinforcing the subgrade, geogrids distribute loads evenly. For example, Cock Lane, a vital rural road connecting the villages of Clavering and Starling’s Green, in Essex, in the United Kingdom faced a critical issue due to the erosion of the adjacent River Stort’s bank. The threat of road foundation failure prompted an emergency closure, allowing only pedestrian traffic for approximately 400 metres. StrataGrid™ was used to construct a reinforced soil wall to address the challenges posed by the unstable riverbank.
Its distinctive features, including a dimensionally stable network of apertures, bidirectional tensile reinforcement capacity, and a UV-stabilised saturation bitumen coating, helped to strengthen the soil along the river bank. The construction process swiftly installed the StrataGrid™-reinforced soil wall along the riverbank, positioned above the existing gabion wall, completing the task in under a week. This expedited response effectively maintained a consistent slope angle of 70 degrees throughout the structure, accommodating a 20 kPa surcharge from traffic loadings on the road, showcasing the geogrid’s efficiency in stabilising critical infrastructure.
Geogrids serve as a preventive measure against cracking in asphalt roads, particularly mitigating reflective cracking caused by propagating cracks from underlying layers to the surface. They reduce crack occurrences, extend road service life, and improve load-carrying capacity. For example, in areas prone to ground movement-induced cracking, integrating geogrids during construction acts as a protective barrier, inhibiting crack propagation.
Consider an asphalt road constructed in an area prone to ground movement, leading to crack development. When geogrids are integrated during construction, they act as a protective barrier against crack propagation. By interlocking with the surrounding soil, as an embedded layer, geogrids enhance the road’s structural integrity, minimising the spread of cracks from underlying layers to the surface. This preventive measure significantly improves the road’s durability, enabling it to withstand heavier loads and ensuring a longer lifespan.
In areas with soft or weak ground, the use of geogrids is helpful in soil stabilisation and reinforcement, which is a core function of geogrids. By providing additional support to the road structure, they’re an excellent choice for road-building material to help keep the terrain stable. This application is especially crucial for the construction of roads for vehicles and rail systems, where the ground conditions may be sub-optimal.
In Andhra Pradesh, India, a container yard encountered challenges due to soft ground consisting of marine clay with a high groundwater table. The subsoil lacked sufficient load-bearing capacity for container stacks and reach stackers. To tackle this issue, a ground improvement project was initiated using StrataGrid Uniaxial reinforcements. Visakhapatnam Port Logistics Park Ltd., the client, recognized the necessity for improvement due to the low safe bearing capacity of marine clay, which posed difficulties for construction vehicles. The proposed solution involved incorporating two layers of StrataGrid Uniaxial reinforcements within the Wet Mix Macadam (WMM) layer, thereby avoiding expensive and environmentally harmful soil replacement.
The road construction process commenced with the preparation and levelling of the existing subgrade, establishing a stable foundation for subsequent layers. A layer of crusher dust was applied to enhance subgrade stability, followed by the addition of coarse sand for further reinforcement. Moorum filling was introduced to compact the layers, ensuring a sturdy foundation. Above the Moorum layer, a geotextile layer acted as a separator, providing additional strength. The incorporation of a 285 GSM PP non-woven layer – a geotextile fabric made from polymeric extrusions – further bolstered the overall structural integrity. A granular sub-base was added to enhance support and distribute loads effectively. Strategically placed within the Wet Mix Macadam layer, two layers of StrataGrid Uniaxial reinforcements created a mechanically stabilised foundation capable of withstanding significant loads. The road structure was then completed with Wet Mix Macadam, a layer of paver blocks serving as the wearing course for a durable and smooth surface, a layer of sand for stability, and a final layer of Dry Lean Concrete, providing a robust and rigid surface suitable for heavy-duty traffic.
The use of geogrids, or other intervention materials such as geocomposites, using a combination of other products like geocells allow for site-specific improvements and resulting cost savings.
Strata Geosystems’ technically advanced products in particular, given their custom development for roadways, reduce the need for extensive soil work, prevent cracks, and enhance overall road performance, resulting significantly in cost reduction. This advantage makes geosynthetics an attractive option for sustainable and budget-conscious highway or in-city road construction projects.
Geogrids can be strategically placed within the road layers rather than relying on expensive soil stabilisation methods or extensive excavation. As a result of using high-strength polymers, the need for costly soil manipulation measures is minimised, and the risk of settlement issues is reduced.
With their ongoing innovations, various types of geosynthetics such as geogrids, geocells and geocomposites, continue to meet diverse industrial needs. Engineers are encouraged to select products tailored to specific manufacturing requirements, offering soil reinforcement, landscape stabilisation, road improvement, etc. Their durability, cost-effectiveness, and environmental advantages make these materials the smart choice in the pursuit of resilient and eco-friendly infrastructure solutions.
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Director, President – Glen Raven Technical Fabrics
Strata/Glen Raven tenure: 10 years/28 years
Total industry experience: 35 years
MBA – Wake Forest University
Directs the strategic direction of Glen Raven’s automotive, protective apparel, military, geogrid, outdoor and logistic businesses.
Director, General Manager, Strata Inc.
Strata/Strata Inc. tenure: 3 years/14 years
Total industry experience: 25 years
MBA – Georgia State University
Led the integration of Strata Inc. business operations into the headquarters of GRTF and transition from USA based to India based manufacturing.
Director
Strata tenure: 17 years
Total industry experience: 47 years
CA – ICA
Played a key role in the establishment of Strata’s India operations. Provides vision for product innovation and leveraging new technology trends.
Global Technical Sales Director
Strata tenure: 7 years
Total industry experience: 32 years
Civil & Geotechnical Engineer (First class)
Provides highly technical and innovative civil engineering solutions in India and around the world. Responsible for the design and execution of large-scale geotechnical projects around the world including Australia, Asia, Europe, Africa, Middle East, and South America.
CTO – Chief Technology Officer
Strata tenure: 9 years
Total industry experience: 48 years
BTech (Hons), MTech (Civil) Both IIT Bombay, DMS (Bombay University), FIE, FIGS, Chartered Engineer
Streamlines the designs of Geosynthetics and has brought innovation in geogrid and geocell design application.
COO – Projects and Sales
Strata tenure: 13 years
Total industry experience: 24 years
MBA – University of Gujarat
Leads the monetization of products and solutions while ensuring highest execution quality and project profitability.
COO – Technical Textiles
Strata tenure: 13 years
Total industry experience: 33 years
BE (Mechanical) – Nagpur University
Drives excellence in process design, product features and cost effectiveness in production.
CFO – Chief Financial Officer
Strata tenure: 8 years
Total industry experience: 35 years
CA – ICA, ICWA – ICWAI
Leads the finance, accounting, taxation, commercial, legal and IT functions and assisting on all strategic and operational matters.
CDO – Chief Development Officer
Strata tenure: 10 years
Total industry experience: 13 years
MBA – ISB, Hyderabad
Leads diversification of the product portfolio, monetizing the new products and ensuring successful sustained financial growth of the company top line.
CEO – Chief Executive Officer
Strata tenure: 14 years
Total industry experience: 42 years
B Tech (Chemical) – IIT Delhi
Leads day-to-day business operations of the company with focus on capacity expansion, product and process improvement.
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