Officine Maccaferri


Ensuring road stability and safety in Kharagpur


We protected road structures from future cracking with MacGrid AR geogrid

The construction agency of the Indian Army needed a durable solution for pavement strengthening at one of their bases in Kalaikunda, Karagpur.

The air force station entry road at Kalaikunda was suffering from severe interconnected cracks. Increased traffic meant the pavement was not able to survive for its intended design life. As a result, the pavement had developed surface cracks that had further deteriorated and become large potholes. Military Engineering Services (MES) decided the pavement needed a durable rehabilitation solution.

When overlaying is not enough

To increase the pavement’s load-carrying capacity, the damaged road had to be repaired by adding an asphalt layer. Overlays are still the most common option for extending the life of distressed pavements. However, while special asphalt mixes can be specified and thicker overlays help to improve performances, rehabilitating cracked roads simply by overlaying is rarely a durable option.

Geosynthetic interlayer: a long-lasting rehabilitation solution

Indeed, the cracks under the overlay can rapidly propagate through to the new surface. This phenomenon is called reflective cracking. To limit this problem and create an economical, long-lasting overlay system, a geosynthetic interlayer can be placed over the distressed pavement prior to the overlay.

For reinforcing the pavement, MacGrid AR 10 was suggested for the interface of the Built up Spray Grout (BUSG) and Bituminous Macadam (BM) layer. MacGrid AR 10A.7 is a reinforcing geogrid material specially developed for pavements. It consists of glass fibre strands arranged in a grid structure with a pressure sensitive adhesive.

To ensure proper adhesion of the MacGrid to the surface, tack coat was also applied over the Built up Spray Grout (BUSG) layer before laying the MacGrid.

The Many Benefits of MacGrid AR

MacGrid AR is a very adaptable material that offers many benefits, including:

  • Reduced reflective cracking: MacGrid AR can reduce reflective cracking in asphalt surfaces caused by the movement, bending and shearing of cracks in underlying asphalt layers or cement-bound substrates. The Stress Absorbing Membrane Interlayer (SAMI) effect can also reduce strain on the surface.
  • Control of differential settlement cracking: Combining MacGrid AR in new unbound aggregate layers can mitigate longitudinal cracking caused by differential settlement between new and existing lanes on widened roads.
  • Reduced surface rutting: MacGrid AR interlocks with the asphalt to restrict lateral movement of particles, reducing permanent strains and surface rutting, particularly in low stiffness mixes subjected to slow and heavy wheel loading at high temperatures.
  • Longer operational life: By delaying the onset and development of cracking, MacGrid AR can increase overall pavement performance and as a result, extend operational life.

The project was completed on March 2017 and a total of 28,050 square metres of MacGrid AR were used. For any further information, please download our case history.

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