Soft fly ash and bituminous materials. Non-traditional additives are

Soft Peaty Clay


With the rapid development going on in the country especially in the
construction of highways a need of competent ground is occurred more than ever.
Most of the ground where the ongoing and proposed projects are to be carried
out consists of soft peaty clay and with a high water table. Peaty clay is the
whether products of organic material mixed with some inorganic soil. In Sri
Lanka peaty clays are with organic contents around 30%-40%. (Kulathilake
& Madusanka, 2011)

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Soil Stabilization is the process of improving the physical and engineering
properties of soil to achieve some predetermined targets. It operates in
various ways such as mechanical, biological, physical, chemical and electrical. (Nima, Ahmad,
Mahmood, & Aminaton, 2015) The most trending
method of soil stabilization is the use of chemical additives. Many researches
have been conducted to identify the most effective way of using chemical
additives. These different chemical soil stabilizers are categorized as
traditional and nontraditional additives. Some traditional additives are lime,
cement, fly ash and  bituminous
materials. Non-traditional additives are enzymes, liquid polymers, resins,
acids, silicates and ions. In Sri Lanka various by products have been used with
cement successfully.


Calcium Carbide Residues


CCR is a by-product of the acetylene production process. It contains
mostly Ca(OH)2. With the increment in the demand for the Acetylene
gas in Sri Lanka CCR is produced in a large scale. It is economically and
environmentally feasible to use CCR as it is freely available and also cleans
the environment by using it rather than racking them up.




In order to describe the theories behind stabilization process it is
essential to study the changes occur in the mineralogy and the molecular
characteristics of the soil before and after the stabilization. For that X-ray
diffraction and scanning electron microscope can be used.











Problem Statement



Most of the construction in Sri Lanka is to be carried out on soft
peaty clay. The soft peaty clay encountered in most of the sites highways are
with high water content, extremely compressible and processes low shear
capacity. So it is essential to improve those geotechnical characteristics of
peaty clay using the method of soil stabilization.


For that the most common way is stabilization using cement. But the use
of cement in such larger scale is unbearable for a developing country like Sri
Lanka. So a replacement for the usage of cement is vital.





Significance of Research



The research is to be carried out to overcome the problems mentioned in
the problem statement. If the test results proves that the geotechnical
characteristics of the peaty clay is considerably improved by the stabilization
process using CCR  it will be a major
breakthrough in the field of geotechnical engineering. Considering the current
construction work carried out using cement as the stabilizer it costs a great
deal of money. But if the CCR mixing with the cement stabilization is good
enough it will save millions for the country as CCR is a by-product of another


It will also be very
much environmentally friendly as until today the by- product of Acetylene gas
production CCR is unused and racked up in factory sites causing many
environmental issues. So taking use of that CCR will be very beneficial.














Scope of the study



Many researches have
been carried out to test the strength development by using the cement as the
stabilizer. So here I will be testing the unconfined compressive strength
development and the shear strength development after 28 days of curing when
cement percentage is replaced by CCR in 3 steps. With the time restrains I will
only be testing for three percentages of CCR.



Cement %


Sample 1



Sample 2



Sample 3




Same set of samples
will be again tested after 90 days of curing to analyze the long term strength


Samples from each
different mix will be tested using scanning electron microscope to study the
mineralogy and the microstructural characteristics of the stabilized peat.


The sample we are
testing is brought from the Southern Expressway extension project. So it will
be only representing the particular site conditions.




Objectives of the research



To propose the best combination of cement and CCR that
achieves the highest strength development.

To study the microstructural phenomena behind the strength development
in stabilized soil