New M.E. Thesis Submitted from CIVIL Student

EFFECT OF ASBESTOS REINFORCEMENT ON UNCONFINED COMPRESSIVE STRENGTH AND SHEAR STRENGTH PARAMETERS OF CLAYEY SOIL By Gurtej Singh,Civil

Abstarct
The soil is the cheapest construction material available in this universe the properties and composition of soil change from place to place. It may happen that soil available for construction is not suitable for intended purpose. The transportation of better quality soil and replacement of soil strata is very costly process. The present trend emphasizes on soil reinforcement. Earth reinforcement is an effective and reliable technique for increasing the strength and stability of soils. The strength characteristics of randomly distributed fibre reinforced soil in term of shear strength, unconfined compressive strength, CBR value, flexural and tensile strength have been reported in the literature by several investigators.
Reinforced soil construction is an effective and reliable technique for improving the strength and stability of soils. In traditions methods of reinforced soil construction, inclusions (e.g. strips, sheets, bars or grids) are normally oriented in preferred direction and are introduced sequentially in alternating layers. That fibre reinforced soil called ply- soil (Mc Gowan, et.al, 1978). In the past practice reinforcement have typically consisted long, flexible galvanized steel strips. This situation is changing today as other types of reinforcement attract increasing attention and wider use. These are woven and non – woven fabrics. These include relatively low modulus natural fabrics has been carried out by a number of investigators.
While considering all as discussed above, it is planned to study the influence of asbestos fiber on shear strength parameters and unconfined compressive strength of clayey soil by taking into consideration the fiber parameters. In present study, Reinforcement of Asbestos with clayey soil is being tried for experimental work. The asbestos is synthetic fiber. They are locally and easily available material. Optimum ratio of the Asbestos that gives maximum gain in unconfined strength & shear strength parameters is evaluated Thus, an attempt is made to improve the properties of the soil in order to improve engineering performances of reinforcing structures such as foundations, retaining walls and dams.
The soil is taken from Khudda Village of Hoshiarpur District. The soil is air dry, mixed and pulverized. The soil sample was taken from concerned soil and mixed thoroughly & dried. The various tests were performed to know various properties of the soil in the laboratories such as Atterberg’s limits, plasticity index and compaction tests. The properties of geotextile materials used were assumed same as supplied by the manufactures.
The following tests are conducted during the present study:-
Sieve analysis
Atterberg’s limits
Compaction test
Direct shear test
Unconfined compressive strength test
The sieve analysis of soil was done. The liquid limit, plastic limit & plasticity index of soil are determined. The classification of the soil is done. From soil classification curve (as per ISC system), it is found that the soil is clay of high compressibility. The maximum dry density and optimum moisture content of soil are also determined by conducting standard proctor test on virgin soil and fibre reinforced soil. The variations of MDD and OMC of virgin soil and soil with different fibre reinforcement (5%, 10 %, 15%) are calculated and compared.
The direct shear and unconfined compression tests were performed for virgin soil and reinforced soil in the laboratory to know the exact behavior of the soil and the improvement in the shear strength parameters and unconfined compressive strength with different fiber reinforcement. Tests are conducted by adding different percentage of asbestos fibre (5%, 10 %, 15%) With direct shear test, the shear strength parameters i.e. cohesion and angle of internal friction with different percentage of fibres (5%, 10%, 15%) are determined and plotted. It is observed that there is also significant increase in cohesion and angle of internal friction (Shear parameters).
The variations in unconfined compressive strength are also predicted by adding different percentage asbestos reinforcement. The results are compared and plotted. It is observed that there is significant increase in unconfined compressive strength.
It is observed that there is increase in the cohesion and angle of internal friction with different percentage of asbestos fibre and optimum increase at 10 % asbestos, which is about 64%. Similarly there is 31 % optimum increase in unconfined compressive strength of soil with the addition of 15 % asbestos fibre.

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