Subgrade Improvement

Sub-grade Improvement

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Sub-grade Improvement


Issues surrounding unbound material-made roads and track beds. Sub-grades and access tracks made from unbound materials can suffer from a number of issues that prematurely age the road; including:

  • Bearing capacity failure
  • Differential settlement
  • Rutting
  • Access over wet/saturated ground
  • Construction layer thickness
  • Weak subgrades

These effects are apparent in many applications including railway track beds, forestry tracks, mine haul roads, construction sites and parking areas.

Geogrid reinforcement solutions to improve performance. Appropriately designed and installed reinforcement, placed within unbound granular layers improves the performance of the road or track bed, extending its life and increasing maintenance intervals. The geogrid reinforcement works in cooperation with the granular materials, helping them to perform better than they would do in an unreinforced state.


Two mechanisms work to increase the elastic modulus and bearing capacity, resulting in improved resistance to deformation and rutting.

  • Lateral restraint to the aggregate particles
  • Tensioned membrane effect.

Improving performance while reducing thickness. In addition, reinforcement can reduce the layer thickness by a third and improve the performance of the subgrade.

Maccaferri’s expertise can bring best-value solutions. Using our design software MacREAD we can optimise the relationship between geogrid (or geotextile) reinforcement and sub-grade thickness to create best-value solutions.