Effectiveness of lime stabilisation on reactive soils for main roads

Wilson, Paul (2011) Effectiveness of lime stabilisation on reactive soils for main roads. [USQ Project]

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Abstract

The Department of Transport and Main Roads (DTMR) manages the state controlled road system in Queensland comprising the major traffic carrying and strategic roads in the state. A vast majority of these state controlled roads are located in areas where the insitu material is dominated by reactive soil. Mixing lime with the reactive subgrade is
a stabilisation technology to not only improve construction workability in these soils but to also reduce maintenance frequency on the road system.

Lime stabilisation is used to modify sub grade soils to improve constructability by improving plastic properties, flocculating particles and drying the material. Studies
indicate that lime stabilisation will improve load bearing capacity and will also achieve long term strength retention.

DTMR Specifications and AUSTROADS Pavement design guidelines for lime modified sub grade recommends the Unconfined Compressive Strength achieve a minimum of 1.5MPa at 28 days (unsoaked). This research will assess current test results against the original test results at completion of construction.

DTMR standards specify that lime stabilisation of subgrade material shall be carried out as 2 passes by applying half the dose in the first pass, waiting 24 hours then applying
the remaining dosage in the last pass. This time period between passes is called the Amelioration Period.

The major issue with having a 24 hour period for amelioration is it takes a longer time to finish construction. This delay has potential impacts on the contractor and exposes the open subgrade to potential weather such as rain for a longer period.

Amelioration is necessary in heavy clays as adequate mixing is difficult to achieve in one pass as heavy clays tend to clump together. Allowing 24 hours between passes permits the lime to flocculate clay particles and improve workability. Amelioration results in better mixing in the second run and construction also becomes easier. This
research will test a range of reduced time period to determine what length of time will achieve the Unconfined Compressive Strength of 1.5MPa.

This research project will confirm that stabilising the road pavement sub grade with lime is an effective and economic solution when applied in the appropriate environment and quantity. It is also expected that improvements will continue to be made to lime
stabilisation specifications.


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Item Type: USQ Project
Refereed: No
Item Status: Live Archive
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Supervisors: Kathirgamalingam, Soma
Date Deposited: 14 Jan 2013 02:54
Last Modified: 03 Jul 2013 01:38
Uncontrolled Keywords: lime stabilisation, amelioration period
Fields of Research : 09 Engineering > 0905 Civil Engineering > 090502 Construction Engineering
09 Engineering > 0905 Civil Engineering > 090507 Transport Engineering
URI: http://eprints.usq.edu.au/id/eprint/22710

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