Projects
Evans Shire Council, NSW
Use of Polymer Stabilisation, June 2003
Overview
 In June 2003, Evans Shire Council evaluated
Polyroad as a pavement stabiliser for one of Council's local roads,
Triangle Flat Road, Rockley to Trunkey. Based on economic grounds and
pre-construction tests results, Council chose to proceed with Polyroad
stabilisation.
Project Site Conditions
The subgrade at the site was tested and found to be adequate in
strength to support construction equipment therefore not requiring
subgrade improvement.
Minor widening of an embankment and cutting were required to provide
adequate final sealed formation widths as determined by Council.
The existing moderate to poor quality pavement material was considered
adequate for modification with Polyroad based on past successful
performance of poor quality pavement materials modified with Polyroad.
The project site typically experiences frequent trucks for local stock
movement and agricultural equipment. In recent years there has been an
increase in timber haulage trucks due to expanding forestry operations in
the area.
 Project Evaluation
One of Council's many concerns regarding pavement rehabilitation was
the lack of local gravel suitable for overlaying. Additionally, the cost
to import suitable gravel was becoming inhibitive considering the
competitive needs and financial demand within Council's local road
network. Council was therefore looking for a cost-effective alternative
both in time, up-front capital dollars and long term savings.
Council arranged pre-construction testing of existing pavement material
mixed with Polyroad PR21L. It was recommended to Council to initially test
the mix by way of Capillary Rise and Swell testing (AS 1141.53). Council
was surprised how effective Polyroad performed in this test whereas the
existing pavement material had completely collapsed within the 72 hour
test period. The Polyroad stabilised sample maintained its cylindrical
integrity throughout the same period. This was also a particularly
important outcome considering the project was going to be built during
winter.
Historical performance information was provided to Council to assist in
their evaluation of whole-of-life-cycle costs. Based on the last ten years
performance on State and National Highways, major rehabilitation projects
incorporating Polyroad had not required any maintenance expenditure to
date (other than cyclic bituminous reseals). Because Polyroad can
accommodate a broad range of material characteristics without requiring
expensive pre-treatment activities eg: cross-blending of varying shoulder
and pavement materials, initial construction costs were less than had been
carried out on some of Council's past projects.
A further saving for Council when incorporating Polyroad was the
absence of a time constraint typically associated with other binders when
mixing and achieving compaction, and that the stabilised pavement can be
tyned and re-compacted at a later stage if delays occurred. Again this was
an added benefit for Council considering the works were being carried out
in winter.
 Construction Results
The project commenced in mid June 2003. As anticipated, delays did
occur due to wet weather typically associated with this time of year.
Council engaged Stabilised Pavements of Australia to spread and mix
Polyroad for the full width of the formation to a depth of 200mm.
Council's own workforce provided all other construction plant necessary to
successfully complete the works. Council achieved densities at
approximately 4% below field optimum.
Due to competing demand for bituminous sealing works to be carried out
before the end of the financial year, the subject project was not primer
sealed for approximately nine weeks. During that time the project site was
exposed to frequent rain and occasional snow and ice. Because Polyroad is
specifically designed to significantly eliminate moisture ingress, no
maintenance works were required during those weeks of inclement weather.
Immediately prior to primer sealing, the granular surface only needed
to be swept by drawn-broom as per standard practice. The primer seal was
successfully carried out and has continued to perform well. The primer
seal will be monitored for at least twelve months before including the
road Council's annual reseal program.
Conclusions
Having achieved a successful outcome while appreciating the extent of
inclement weather during and after construction, and unfavourable time of
the year, Council is more than satisfied with what Polyroad delivered
under difficult circumstances. Evans Shire Council has identified the
following major advantages of Polyroad:
- waterproofs existing materials
- treated pavement remains flexible
- allows unlimited working time
- accepts a wide variation in material quality without sacrificing
performance
- allows increased productivity
- provides substantial benefits to Council
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