Projects
Yass Shire Council Project Update
Use of Polymer Stabilisation
October '98 Update
Overview
In 1996 Yass Shire Council began evaluation of Polyroad as
a pavement stabiliser in heavy patching work on two RTA Main Roads (MR84
and MR56) maintained by the Shire. The results were so encouraging that
Council now use Polyroad for both general road rehabilitation and
maintenance patching on its own shire roads and on RTA roads.
Heavy Patching Using Polyroad
Heavy patching is classified as a pavement failure
requiring machinery to carry out the repair. Generally the areas for heavy
patching display severe rutting and surface cracking generally due to the
presence of excess moisture in the pavement and subgrade. The majority of
heavy patching within the Shire occurs on heavily trafficked roads.
In the past, heavy patching by the Shire has involved the
excavation of the patches with a backhoe generally to a depth of 300 to
400mm, backfilling with local natural gravels, compacting and surface
sealing.
The Polyroad treatment used involved a 1.5% by weight
additive rate to a depth of 200mm. The Polyroad was spread over the area
and mixed into the pavement using a stabiliser that pulverised, mixed and
incorporated the required moisture in a single pass. Conventional
processes were used to grade and compact the mixed pavement.
The Results
 Despite the sections
patched being in areas with a high and fluctuating water table the
Polyroad stabilised patches are showing no signs of deformation or failure
after 18 months. This contrasts with the traditional methods previously
employed which normally produce a 20% failure rate in the same period. The
results in these adverse conditions have even surprised the construction
crews and experienced works supervisors.
One of the benefits of patching by in-situ stabilising
using Polyroad is the great improvement in productivity possible over
conventional methods - often some 300% to 400%. The improved productivity,
the improved performance and the reduction in retreatment due to failures
of previous works offers substantial benefits to both the Council and the
community.
General Road Rehabilitation Works using Polyroad
Yass Shire undertook five rehabilitation projects on RTA
Main Roads using Polyroad. These pavements had all passed their useful
life and exhibited rutting, heaving and severe potholing. The pavements
had been subject to regular heavy patching over the previous three years.
All but one of the pavements were stabilised to a depth of
200mm with 1.5% Polyroad, the remaining to a depth of 150mm due to the
presence of water service.
The Results
All the pavements continue to perform well after eighteen
months of service. One section of pavement was sealed with inadequate
compaction due to the need to protect it from the weather and traffic over
a weekend. One of the advantages of Polyroad compared with conventional
stabilising agents is that it acts physically and is not cementitious.
Because of this it can be re-mixed at any time and re-compacted. The
section in question was ripped, re-compacted and sealed and is now
performing well.
Conclusions
The results have been sufficient to change Yass Shire
Council's method of heavy patching. Work of this nature is now carried out
with Polyroad. The Council now also use Polyroad for general
rehabilitation of both Shire and RTA roads. The Shire has identified the
following major advantages of Polyroad:
- waterproofs existing materials
- treated materials remain flexible
- allows unlimited working time
- accepts a wide variation in material quality without sacrificing
performance
- allows increased productivity
- provides substantial benefits to Council and ratepayers alike.
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