Getting the Subgrade Fixed
From AustStab News (newsletter of the Australian
Stabilisation Industry Association), Volume 7.2, June 2001
Road stabilisation is a very efficient process and insitu works allow the
base material to be strengthened using a range of binders to meet the
specific pavement material type and the cost of available binder.
But what happens when the subgrade material is too weak to support the
traffic? The RTA (NSW) and Queensland Main Roads, among others, are now
utilising profilers and stabilisers to strengthen subgrades in a very simple
insitu process.
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(a) Urban street. |
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(b) Rural Highway site. |
"The modified profiler removing existing base material and
stockpiling material on adjacent roadway as an initial process before lime
stabilising the subgrade."
The stages of construction are:
- Close half road.
- Remove existing base material to up to 300 mm depth using a 2.6 m wide
modified profiler and stockpile material on closed road surface adjacent
to excavation.
- lnsitu stabilise subgrade using 2-6% quicklime to a depth of 250 mm
(depending on testing).
- Reinstate base materials on newly stabilised subgrade, compact and
trim allowing traffic to run on the lane overnight.
- Carry out task on other section of carriage way.
- Swap road closures sides and complete other half of roadway.
- Seal road and complete line marking.
Advantages of this process are:
- Existing levels of pavement can be maintained (desirable in flood
plains etc.).
- All existing materials are utilised - no waste of valuable resources.
- Up to 1.5 km long by 2.6 m wide can be treated in one day.
- Minimum costs and disruption compared to conventional methods of
subgrade strengthening such as subgrade replacement.
- Modified profiler adds moisture when excavating existing pavement
material to assist with the compaction of base materials allowing speedy
reinstatement and compaction of the base materials.
"Lime stabilisation of the weak subgrade
material."
For more information Contact Us
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