Road Recycling

Stabilisation methods

Road recycling is a process that has been widely adopted for rehabilitation of road assets throughout the pavement industry for over 60 years. Road recycling is not only a cost efficient process but generally offers construction time savings and sustainable solutions.
Environmental benefits of road recycling often include the following aspects:

Significant reduction in the use of virgin quarry materials
Minimal generation of construction waste through the use of insitu material
Reduced trucking movements as a result of limited importing or exporting of materials form site
Reduction in emissions, energy use and noise due to shorter construction duration

With one of the largest ranges of reclaimer/stabilisers and binder spreaders within Australasia, SPA has the ability to provide road recycling solutions for all bound and unbound pavement materials in any project environment or material type.

Our engineering staff can assist in developing a suitable investigation and design process to ensure we deliver long term rehabilitation solutions within your assets. Please refer to our section on stabilisation methods below to identify what stabilisation methods may be applicable for your project.

From the most commonly used method of cement stabilisation, to the use of foamed bitumen within heavily trafficked pavements, we can provide rehabilitation options for any circumstance. Examples of previous projects encompassing road construction stabilisation can be found within our projects section of the website.

Pavement Construction

Stabilisation methods

Stabilisation is a widely used process within road construction projects and is incorporated within subgrade, subbase/select fill and basecourse layers alike. Stabilisation is predominantly used within road construction to provide cost savings from either the improvement and/or modification of insitu or locally won materials.

SPA has been delivering benefits to clients through stabilisation within road construction from small residential streets to large national highway projects successfully for many years. Our engineering staff can provide assistance in identifying opportunities within road construction projects to not only offer direct cost benefits but also offer the advantages of construction time savings, sustainable construction methods and construction risk mitigation solutions.

Stabilisation Methods

At SPA, the combination of our experience, engineering skills and range of plant and equipment enables us to service the market with a significant number of stabilisation methods. Drawn from the basis that stabilisation is the process of improving or modifying any soil or pavement material, we are able to offer solutions for all pavement applications



Insitu stabilisation of basecourse materials is the most commonly used stabilisation method within the pavement industry. Basecourse stabilisation is generally the most cost effective means of rehabilitating low to medium traffic volume pavements and can include the use of nearly all binder types dependent on the characteristics of the host material.

Common binders used for basecourse stabilisation include cement stabilisation through cementitious binders however foamed bitumen is becoming a common treatment option for heavily trafficked roads.

Deeplift stabilisation as the name suggests involves a deep, ‘single lift’ mixing process that is common for medium to high traffic volume pavements. SPA pioneered this process within Australia in conjunction with the RTA in NSW during the mid 1990’s which included the importation into Australia of specialised plant to ensure a homogenous recycled pavement layer.

Deeplift stabilisation is commonly used with either a flexible or slow setting binder to ensure that higher UCS strengths are maintained without inducing any block cracking. Deeplift stabilisation provides distinct construction duration advantages over alternative methods.



Subbase stabilisation is commonly used to improve the strength or permeability of the host material within either pavement rehabilitation or construction applications. Common binders for subbase applications include cement, lime or a blend in conjunction with slag or fly ash.

Subgrade stabilisation is most commonly carried out on materials of relatively high plasticity and generally involves the use of lime. Subgrade stabilisation results in significant improvements in CBR strength and will therefore reduce the basecourse or subbase layers within the overall pavement design.

SPA commonly utilises subgrade stabilisation for reasons additional to strength gain which include improvement in material impermeability, development of working platform, improvement of material workability or reduction in plasticity index.

Unsealed Roads

Formation Improvement

SPA provides solutions for unsealed roads which incorporate either binder or granular stabilisation in order to provide a more cost effective whole of life cycle solution in comparison to conventional resheet and maintenance grading alternatives.

The use of stabilisation to improve unsealed roads can not only provide strength gain but also protect the pavement during periods of high rainfall to ensure that access and use of the asset is maintained at all times.

Improvement of a pavement, building or other civil construction formations is a common solution of applying stabilisation methods to improve insitu materails which result in reduced construction costs for developers and distinct environmental advantages in relation to reduction of virgin materials and generated construction waste.

Foamed bitumen

Dry Powdered Polymers

Foamed bitumen layers through it cost effective nature and various respective benefits against alternative options.
Foamed bitumen involves the addition of typically 2.5 – 3.5% foamed bitumen (C170 bitumen foamed by water/air) which coats the granular fines producing a matrix with which to bind the coarse aggregate.
Foamed bitumen is commonly used in relatively medium/high traffic loading locations and its impervious nature means it is ideal for use within climates of high rainfall or where pavement saturation is common.

SPA is proud to have been a market leader in both the reintroduction and development of foamed bitumen within the Australian market since the late 1990’s which extends to plant, investigation and design and works methodology.

Stabilisation with Dry Powdered Polymers is an innovate method for modifying the properties of insitu materials. Dry Powdered Polymers such as ‘PolyRoad’ preserve the dry strength of insitu materials to ensure they maintain strength during periods of high rainfall and subsequent pavement saturation.

The use of Polyroad as a dry powdered polymer has been widely used by SPA in conjunction with the Road and Maritime Services (RMS) in NSW with great results, particularly in marginal, locally won gravels.


Enclosed Integrated Spreading System (EISS)

Granular stabilisation is a common method used by SPA on unbound granular materials which often involves the addition of either just moisture to existing materials or both gravel and moisture. Commonly used for unsealed roads, this solutions improves the grading and natural mechanical interlock of the host material in order to provide an improved CBR for traffic loading.

Granular stabilisation through the use of an SPA reclaimer/stabiliser is an extremely effective means of rehabilitating or constructing remote, unsealed roads whereby use of locally won materials and effective utilisation of moisture is of primary concern to ensure cost efficient solutions.

EISS has been developed by SPA to provide a process whereby dust associated with binder spreading and mixing activities is minimised through an enclosed application. SPA has specialised transfer vessels which enable us to provide the purpose built reclaimer/stabiliser with both dry powder binder and water in a single mixing pass with minimal dust which is commonly used within urban areas. Our EISS capability is quality controlled and can be monitored through either the use of trays and scales or the on board load cells to verify binder usage.

Environmental Solutions

Stabilisation is successfully proven method for treating or encapsulating contaminated materials as an alternative to disposal options to not only reduce costs but limit the use of limited land fill resources. These techniques are commonly used by SPA for examples such as Acid Sulphate Soils or Tar Bound Materials.