The stabilisation process is not confined to new road construction or rehabilitation, but can also be successfully used for a variety of applications to dam construction, land reclamation, treatment of acid sulphate soils, contaminated sites and salinity.  This web page contains various topics that  are current and bring together state-of-the-art stabilisation information.

Acid sulphate soils

The Association’s lime supplier members have produced a lime supply specification for the treatment of acid sulphate soils.  Our members have found that the supply and application of lime treatment for acid sulphate soils is generally poor and there is also no monitoring program to ensure that the soils have been effectively treated.  To get a copy of the lime supply specification, click here.

Salinity

The first National Local Government Salinity Summit was held in Moama (NSW) in July 2001 and brought together experts on the increasingly worrying issue of salinity and emerging problems on agricultural land and infrastructure. A technical paper, Maintaining the road infrastructure in saline prone areas, prepared by several AustStab members and the IPWEA local Government Salinity Management Handbook provides a starting point for researchers and practitioners on the topic.

IPWEA has prepared a draft Salinity Management Handbook as a resource guide for the Public Works Professional. The Handbook describes the current salinity situation in Australia as well as pro-active approaches that can be taken to identify risks and emerging problems at a local level. Remedies and mitigation measures that can be employed are also suggested.  Copies of the handbook can be downloaded from this website www.auststab.com.au/salinity/ .

Another paper worth reading is titled Practical measures within road reserves to avoid development of catchment salinity problems and was prepared by Ken Porter and Craig Clifton.

There is no doubt that salinity and rising water tables affect the road infrastructure.  The casual observer will see culverts and deteriorating roads, leading to conditions that are unacceptable, sometimes dangerous, and inextricably linked with rising salinity levels. 

A clear example of the salinity problem in the context of roads, is damage caused by salt and water with water or high levels of moisture being a common cause of pavement distress on local roads and highways.  The condition of groundwater salinity is a complex issue of water and salt cycles above and below the ground.  Much of the damage to road infrastructure in Australia appears to be due to rising water tables and high saline contents.  The extent of the problem and areas at particular risk for road infrastructure were well documented in an Austroads report published in 2004.

A paper prepared by AustStab in 2005 and titled Techniques to use on roads affected by salinity focuses on the impact of salinity on urban roads where it is assumed that a kerb and gutter is used at the edges of the road pavement.  Both light and heavily trafficked routes are considered in this paper.  

Austroads published a report titled  Salinity and rising water tables – Risks for road assets (Report No. AP-R246).  This report documents work undertaken in relation to the Austroads Business Systems Project and the purpose was to identify the potential impact of dryland salinity on construction and maintenance of the road asset.  These impacts may require changes to the way road design, construction and maintenance is carried out if an acceptable service life is to be achieved, which in turn may lead to cost increases. 

This report is structured as follows:

Part A - Provides some insight into how high water-tables and salinity are presently affecting road assets in Australia.
Part B  - Provides an overview of recent studies of ‘damage cost functions’ that can be used to estimate the economic costs of salinity and rising water-tables on road infrastructure.
Part C - Provides a summary of the main salinity management options available to land, water and infrastructure managers in salt-affected catchments.
Part D - Outlines a program for future research.

To download the report click here.

Granular stabilisation

Previously known as mechanical stabilisation, and the term now used by AustStab and Austroads, is granular stabilisation.  Traditional quarries used to mix various parts of the deposit to form a particular class of road base material.  The use of insitu granular stabilisation is far more cost effective as everything is done in place and no material has to be removed to another site. In some cases a granular overlay material is spread on the road and mixed with the existing material to enhance the particle size distribution (ie grading ). 

Granular stabilisation is an effective treatment for both unsealed and sealed roads, and shoulder widening. Sealing may be by bituminous products or granular materials.

A copy of a presentation on granular stabilisation is available - Click here (File size 545 kB).