Abstract :
Shrinkage
limits of fiber reinforced and unreinforced samples were investigated using the
test procedure outlined in ASTM D4943-02. Because of standard sample size
limitations and the difficulty in soil-fiber mixing to obtain uniform
distribution of fibers within the soil, shrinkage limits of specimen reinforced
with 8% fibers and varying lengths could not be determined.
The
geotechnical engineers design foundations and other structures on the soil
after investigation of the type of soil, its characteristics and its extent. If
the soil is good at shallow depth below the ground surface, shallow foundation
such as footings and rafts, are generally most economical. However if the soil
just below the ground surface is not good but a strong stratum exist at a great
depth, deep foundations, such as piles, wells and caissons are required. Deep
foundations are quite expensive and are cost effective only in the where the
structure to be supported is quite heavy and huge. Sometimes the soil
conditions are very poor even at greater depth
and it is not practical to construct even deep foundation. In such cases
various methods of soil stabilization and reinforcement technique is adopted.
The objective is to improve the characteristics at site and make soil capable
of carrying load and to increase the shear strength decrease the
compressibility of the soil.
From a
critical receiver of literature on the use of randomly distributed waste
plastic fibers for the stabilization of soil which are having very poor
strength characteristics, the following conclusions are drawn:
1. The soils are reinforced with randomly distributed
polypropylene fibers and the CBR values obtained for this type of soil is
around 38% high than the unreinforced soil. For the CBR test we have used
cement as a binder, even though the percentage of cement is very high fiber content is responsible for
the increase in CBR value.
2. The value of cohesion also increases due to the
inclusion of fiber. The variation of cohesion with percentage of fiber content
is observed to be non-liner . The value obtained for cohesion (c) indicates
that soil obtained is of very stiff nature.
3. In general angle of internal friction increased with
fiber content. The variation of with percentages of fiber contents leads to a
conclusion that the behavior of the fiber included soil can be non-liner variation because the
reinforcement materials exhibited a distribution with horizontal and vertical directions to the
shear surface.
4. The shear strength of fiber reinforced soil is
improved due to the addition of the waste polymer fibers and it is a non linear
function. Up to a critical fiber content shear strength increased considerably
and later small reduction is observed. However shear values are greater than
unreinforced soil.
5. The soil stabilization with waste fibers improves
the strength behavior of unsaturated clayey soils and can potentially reduce
ground improvement costs by adopting this method of stabilization.
6. The addition of randomly distributed polypropylene
fibers resulted in substantially reducing the consolidation settlement of the
clay soil. Length of fibers had an insignificant effect on this soil
characteristic, where as fiber contents proved more influential and effective.
7. With increase in fiber content the swelling after
unloading is reduced to almost half of the unreinforced situation. At constant
fiber content the length of fiber does not have much effect on swelling.
8. The shrinkage limit is showing a rising graph with
both the increase in fiber content and fiber length. It indicates that the soil
is susceptible to less volume change and it has got enough tensile strength
with reinforcing.
9. Fiber reinforcement significantly reduced the extent
and distribution of cracks due to desiccation as observed by the reduced
number, depth and width of cracks. These results show that it can be used for
covering waste material in containments and also can be used for canal slopes.
Download :
fiber reinforced report
Download :
fiber reinforced report