17-09-2014, 03:31 PM
Improvement of Bearing Capacity of Clayey Soil with PET Bottle Strips
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Abstract
Recycling plastic waste from water bottles has become one of the major challenges along the world. As part of waste
management, an experiment work has been done with one type of locally collected clayey soil reinforced with randomly mixed
PET bottle strips of optimum percentage i.e. 1% by weight with varying aspect ratio of 1, 2 & 3 of constant width 5mm. The
work has been done with the objective of examining the improvement of bearing capacity of clayey soil by mixing PET bottle
strips. A series of experimental model footing tests were carried out on different mixes of soil (at OMC) and PET bottle strips
adopting standard procedures for plate load tests and following model test procedure as carried out by scholars. The present
study provides an approach for the use of plastic waste as reinforcement material in soil.
INTRODUCTION
Soil is a poor structural material because it is weak in
tension. Reinforced soil is a generic term that is applied to
structures or systems constructed by placing reinforcing
elements in soil to provide improved tensile resistance.
Reinforced soil structures are very cost-effective which
explains why the concept has emerged as one of the most
exciting and innovative civil engineering technologies in
recent times.The concept of soil reinforcement was first
developed by Vidal (1969). He demonstrated that the
introduction of reinforcement elements in a soil mass
increases the shear resistance of the soil matrix.In one of the
earliest papers on the use of plastic waste in combination
with soil, Consoli et al. (2002) indicates that one of the most
promising approaches is the use of fibre -shaped waste
materials in the combination with soil and cement. Materials
such as polyethylene terephthalate (PET) plastic bottles are
profusely and widely produced, yet used little for
engineering purposes, and the overwhelming majority of
them are placed in storage or disposal sites. Recycling of
plastic waste from PET bottles is becoming one of the
challenging enterprises worldwide.In this study, the potential
benefits of reinforced soil foundations over unreinforced soil
MATERIALS FOR STUDY
In the present study two materials have been used, one is
locally collected clayey soil and other is plastic fibre strips
obtained from PET bottles.
The details of the materials are given below:
A. Soil
In this study, an experimental work has been under taken
with one type of locally collected clayey soil. The properties
of soil was determine by standard test procedures as per
relevant IS codes and are furnished in table
EXPERIMENT METHODOLOGY
The model footing tests was performed in steel box. Friction
between the sidewalls of the box and the backfill was
minimised by lubricating these area to practically insulate
the soil mass from the frictional effects. The box was
sufficiently rigid to maintain it shape while testing on model
footings. The dimension of the tank was kept 6 times of the
width of the model footing so that it should not include any
boundary effects. The depth of the tank was kept 4 times of
the width of the model footing. The thickness of walls of thetank is kept enough to withstand lateral expansion under the
loads. The soil is compacted in the tank in numbers of equal
layer using constant compaction energy such that void ratio
is maintained constant with depth throughout tests. The soil
in the tank was compacted in respective Optimum moisture
content
TEST PROGRAMME
Standard proctor compaction tests, unconfined compressive
strength tests & unconsolidated undrained tri-axial tests at
OMC were carried out and it was observed that an optimum
value of fibre percentage by weight was 1% (Improvement
Of Undrained Shear Strength Of Clayey Soil With Pet Bottle
Strips by Raghu P.V, Acharyya R & Mukherjee, S.P -
Proceedings of Indian Geotechnical Conference December
22-24,2013, Roorkee). Therefore the model footing tests
were carried with 0 & 1% with different aspect ratios. Small
Scale footing tests were carried out with 5cm square steel
plate of 5mm thickness. Accordingly tank of 30 cm X 30 cm
X 20cm was used. Proving ring of required capacity was
used to load the footing with the required amount. The load
was applied well beyond the value obtain from theoretical
formula so as to obtain clear failure load. The test
programme is presented in the table III below.
CONCLUSION
Randomly distributed PET bottle strips would increase the
bearing capacity by 51% along with the gain in settlement
behaviour