Rajagopal, K., Veeraragavan, A., Chandramouli, S. (2012). “Studies on Tough-Cell Reinforced Road Pavement Structures,” Geosynthetics Asia 2012, Thailand.
Study demonstrates Tough-Cell reinforcement increases the stiffness and elastic modulus of pavements by a factor of up to 2.92, in addition to increasing pavement surface life from 16 years to 20 years, and reduces the thickness of granular layers by as much as 50%.
Too often, the scarcity or distance of natural resources, makes the strengthening of highway pavements a costly or lengthy exercise. Building on previous studies by Bathurst, Han, Pokharel and others, this study provides academic proof that Neoloy Tough-Cell reinforcement increases the stiffness and elastic modulus of pavements.
Validation – Field study
A field test was carried out on samples from an access road in Phaltan, Maharashtra, consisting of water bound Macadam and granular sub base. The performance of an Neoloy Tough-Cell reinforced pavement and adjacent unreinforced sections were monitored from March to December 2010, during which there was unusually heavy rainfall. The following observations were made:
- The unreinforced pavement underwent severe rutting and had to be reconstructed at least 3 times
- The unreinforced pavement experienced severe surface depressions
- The Neoloy Tough-Cell reinforced pavement maintained a uniform surface
- There was no change of dimensions when pieces of Neoloy Tough-Cell were exposed to 100°C temperature in an oven for a 1 hour duration
Project installation of the Neoloy Tough-Cell Reinforced Base Layer and infill with GSB (granular sub-base) material
Validation – Laboratory test
The laboratory test was designed to further explore the results of the field study. Water bound Macadam and granular sub base were tested as a subgrade in a test tank. Plate load tests were conducted on 3 different thicknesses of Neoloy Tough-Cell layers. Several tests were performed on varying combinations of Neoloy Tough-Cell and infill material.
Results – Improved modulus performance
Calculations, using Young’s modulus values, showed the following results:
- In field tests, Neoloy Tough-Cell improved elastic modulus by a factor of 2.75
- In laboratory tests, Neoloy Tough-Cell improved elastic modulus by a factor of 2.84 in 50 mm and 100 mm thick sections, and by a factor of 2.92 in a 150 mm thick section
The study also demonstrated the following results:
- Adding a Neoloy Tough-Cell layer significantly reduced the vertical pressures transmitted by the subgrade layers, increasing pavement surface life from 16 years to 20 years
- The use of Neoloy Tough-Cell layer reduces the thickness of granular layers by as much as 50%
Benefits – Low damage, low thickness means reduced cost, faster construction
Using one or more Neoloy Tough-Cell layers was found to increase the structural stiffness of the pavement and its elastic modulus, generating significant benefits:
- Reduced pavement thickness, allowing for a significant reduction in total cost of the pavement system per unit area
- Reduced pavement thickness requiring less material and therefore faster construction
- With fewer materials required, reduced transport costs constituting a reduced carbon footprint