Use Advanced Technology and Sand for Highway Construction
Neoloy® Geocells double the lifespan of highway using locally available sandy soil.
The Western High-Speed Diameter Road (WHSD) is a 40 km North-South 4-8 lane motorway built to relieve congestion in St. Petersburg. It was the first urban high-speed toll road in Russia, with a planned traffic capacity of 1,000,000 vehicles monthly.
The original plan for the 26 km northern section called for a conventional pavement design on top of a road embankment and 1.0m thick working platform of sandy soil. This was comprised of a 70 mm subbase layer, 410 mm thick granular base layer and a 230 mm thick asphalt layer.
Neoloy Solution – Verification
An alternative design was presented to the NHC consortium responsible for the project, and a proof of concept project was implemented on a section of the A-118 Motorway. Based on Neoloy® Geocells, the goal of the design was to replace the expensive imported granular materials with locally available infill..
Stress monitoring by cyclical plate load tests (Russian standard: GOST 20276-99) of pre-installed pressure cells on sand subgrade verified that the Neoloy Geocell design improves the granular subbase modulus by a factor of 2.45. It also reduced vertical stress by ~50% and allowed a 13% reduction in asphalt thickness.
The demonstration project convinced the project’s commercial and technical experts to adopt and implement the Neoloy Geocell based design for the WHSD road project.
The Neoloy Geocell is a 3D mechanical stabilization technology which stiffens the confined layer. The unique properties – high dynamic stiffness, creep resistance and tensile strength – of the Neoloy novel polymeric alloy (NPA) enable the following design benefits:
- Increased modulus of granular layer (2.45x)
- Decrease in accumulated plastic strain in lower granular layers
- Lower tensile strain at bottom of asphalt layer leads to lower fatigue, higher design life (x47%)
The Neoloy Geocells also reduce vertical stress by 50% with a significant decrease in the pavement thickness, while improving traffic capacity and pavement design-life.
Delivery and installation were undertaken to the full satisfaction of the clients. The road is in operation since 2013 with no maintenance required.