Critical Assesment on the Stabilization Of Expansive Soils by Different Techniques
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Date
2015-10
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Addis Ababa University
Abstract
The evaluation and criticism of the stabilization of expansive soil by different
techniques base on the researches done. To list them:-
1. A Research on “Stabilization of expansive clay soil with sugar cane molasses
and cement” for the Study Area of Modjo – Ejere – Arerti – Sembo Road
Project with different mix ratios and come up with a finding that Soil treated
with cement and molasses combination gave a significant improvement in
strength than when cement and molasses alone and meaningfully reduced
swelling property of the expansive soil. Also it was effective in arresting linear
shrinkages and eliminated shrinkage cracks that were observed in soil
treated with cement alone.
2. A research on “Stabilization of Expansive clay soil with lime “ for the Study
Area Adura-Burbey Road project, Gambella and come up with a finding
that expansive Soil treated with the addition of lime alone gave a reduction of
the free swell, reduction in plasticity limit; improve the CBR, increase of the
unconfined compressive strength.
3. A research on “The chemical treatment of “Block Cotton” soil to make it
usable as a foundation material”for the study area of ten samples from Addis
Ababa ‘’Black –cotton’’ soils and come up with a finding that the geotechnical
property these expansive soils have been improved from a vary high
expansive to a moderate expansive soils by the addition of 6% lime and 12%
cement independently by dry weight of the native soil.
4. A researcher on “Evaluation of Sodium Silicate and its Combination with
Cement/Lime for soil stabilization” for the study area of in situ soil of Addis
Ababa’s Bole Senior Secondary and Preparatory School and borrowed
material from Gergi-Bole Road section and has come up with the finding that
Sodium Silicat has an inhibiting effect on strength development of clayey
sand soil-cement mixture when its quantity is increased to and beyond 2.5%
by dry weight of the soil. But Applying lower amount like 1% sodium silicate
AAiT
School of Graduate Studies
by dry weight of the soil in concert with ordinary Portland cement is used it
has positive implications on strength development .But using Sodium silicate
as chemical stabilization with or without lime is not a suitable additive for
montmorillonitic clay (expansive soil) stabilization.
5. A researcher on “Bagasse Ash as a Sub-grade Soil Stabilizing Material” for
the Study Area of Addis Ababa, Bole Sub City around Bole Medhanialem
church and come up with a finding that While treating expansive soil, with
an increase in the bagass ash addition alone, there is a decrease in free
swell, free swell index and free swell ratio but it is with a slight decrease in
the plasticity and a slight increase in the CBR value. But the addition of
bagasse ash in combination with lime improved the CBR value, and
plasticity index decreased significantly.
So, from critically evaluating these, the lime content increase the PI ratio,
Free swell ratio and CBR swell ratio all shows increasing, indicating that the
PI, the free swell and the CBR swell values are all decreasing in a direct
proportion. In addition, in case of the free swell ratio verses the lime content
it can be approximated that all the graphs do overlap one over the other
meaning the testing procedures and the precision during the testing are
approximated to be equal. Yet, a more different scenario is observed during
the CBR swell tests verse the lime content this may arise due to the soil
sample preparation and testing procedures.
Another evaluation is as the cement content increase the PI ratio shows
increasing indicating that the PI values are decreasing .In addition ,it can be
seen that the PI ratio gets flat beyond some 6% to 12% cement addition
indicating that further addition do not have an significant impact on the PI
value.
Key Words: Cement, lime, Sodium silicate, Bagass Ash, Expansive Clay
Soil, Sugar Cane Molasses, Soil Modification, Soil Stabilization. Critical
Review
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Keywords
Key Words: Cement ;lime; Sodium silicate; Bagass Ash; Expansive Clay Soil; Sugar Cane Molasses;Soil Modification ;Soil Stabilization; Critical Review