Stabilization of Expansive Clay Soils Using Quarry Waste
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Date
2017-12
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Addis Ababa University
Abstract
Extensive researches has been carried out by different researchers to find solutions associated
with problems of expansive soils .The construction industry has presented a number of ground
improvement techniques to modify expansive nature of soils and to minimize or eliminate the
danger of damage of structures because of heave and shrinkage. Soil-stabilization is one among
different ground improvement alternatives being used worldwide. Soil-stabilization is any
treatment applied to a soil to improve its strength and reduce vulnerability to heave. There are
different methods of soil stabilization that have been identified to improve the expansive
nature of soils. Due to the growing cost of these stabilizing agents and the need for the
economical utilization of industrial and agricultural wastes, in modern days of industrialization it
becomes imperative to use waste materials from various industries for expansive soil
stabilization.
This research work is aimed at exploring whether a waste from quarries i.e. quarry dust, can be
used as stabilizing material for expansive soils or not. The performance of quarry dust was
evaluated based on laboratory test results on expansive soil collected from Addis Ababa around
Bole area. The soil was initially characterized and classified based on index tests and found to be
A-7-5 according to AASHTO and CH according to USCS systems. Soils with this category have
very low load bearing capacity and are highly expansive soils. The effects of quarry dust on the
engineering properties of the soil were evaluated by treating the soil with quarry dust passing No.
200 sieve in stepped concentration of 2%, 4%, 6%, 8%, 10%, 20% and 30% by dry weight of the
soil. All treated soil samples were cured for 7 days before the tests were conducted. Test
specimens were subjected to Atterberg limit, free swell, swelling pressure,UCS, compaction and
CBR tests.
The analysis of results showed reduction in plasticity index, free swell, swelling pressure, OMC
and UCS with all higher quarry dust contents and a slight increase in the maximum dry density
and soaked CBR values. Generally, it was concluded from the results that quarry dust is not an
effective stabilizer for the improvement of most of the geotechnical properties of the soil, while
swelling properties showed significant reduction to the level in which the uplift pressure of
expansive soil can be controlled by the counter pressure of light weight structures.
Additional study has also been incorporated to investigate the effect of blending granular quarry
waste material (Passing No.4 and retaining No.200) with expansive soil, so that it can be used as
a mechanical stabilizer for expansive subgrade soil. Compaction and CBR tests were performed
and the results showed a very slight improvement in both test values. From this study it was
found out that soil mechanically stabilized with granular quarry waste do not meet the minimum
requirement of ERA pavement manual specification for use as a sub-grade material in road
construction, in the context of this study.
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Keywords
Expansive Clay Soils, Quarry Waste, Stabilization