Bituminous stabilisation is used to introduce cohesion non plastic material or to make cohesive material less sensitive to less of stability with increased moisture.

The process is very successful with granular material in bases. The resultant pavement performs as a low modulus asphalt which is used often as a substitute in the layers below wearing course.

Bituminous stabilisation in recent times has used either foamed hot bitumen or bitumen emulsions to introduce the binder into the mix.


Chemical stabilisation is the mixing of various chemicals into the pavement and not just the mere spraying of chemicals to the surface of the road.

The action of chemical binders in the pavement and subgrade materials are:

AdhesionAct as a glue in bonding particles
AdsorptionTo attract atmospheric moisture to reduce dust emission
DilatantTo dispel water when compacted under vibration
DispersantSeparates fine particles from each other
IonicBonding from a reversing of the electrostatic charge on some soil platelets
SurfactantTo reduce surface tension.


Granular stabilisation is the blending of the insitu material of various pavement layers or work one or more introduced granular material. The process can be used in a mixing plant to blend various materials.

The process is designed to improve poor quality materials by adding product to give a conforming products by improving the grading or reducing the percentage of poor quality elements.

It is used by adding material to:

  • Poorly graded product
  • Done or river deposited products
  • Silt/sand/clay soils
  • Crusher runs
  • Waste or industrial products
  • High plastic materials

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Lime is a very effective binder for plastic soils. Usually in clays there is a degree of pozzolanic material which chemically reacts with calcium hydroxide to forma cementitious material.

Lime is usually used in subgrades or unsealed roads resulting in:

  • Improved strength
  • Improved workability
  • Elimination of swelling
  • Improved grading
  • Greatly improved water resistance

These improved properties achieve major advantages in pavements.

Subgrades are:

  • Stronger therefore reduce the pavement thickness as stabilised material can be treated as a lower subbase layer
  • Improve water resistance of overall pavement.
  • A working platform that allows construction to proceed in wet weather

Unsealed Roads

  • Require less maintenance
  • Greatly reduced dust generation
  • Far safer driving surface especially in wet weather

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