Influence of kenaf and coir fibers in problematic soil for road works
Pavement construction on natural subgrade is most concern nowadays due to the variation of subgrade soil. The properties of existing subgrade soil play the important role in producing the best condition of road especially in rural area. The usual approach in solving weak soil is by remove and rep...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2019
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/92868/1/FK%202020%2093%20-%20IR.1.pdf |
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| Summary: | Pavement construction on natural subgrade is most concern nowadays due to
the variation of subgrade soil. The properties of existing subgrade soil play the
important role in producing the best condition of road especially in rural area.
The usual approach in solving weak soil is by remove and replaces the existing
soil with any stronger materials, which is expensive. One of the economical
ways to improve the soil properties is soil reinforcement using natural fibers.
Use of natural fibers is advantageous due to their availability, cost
effectiveness, favourable strength and environmental friendliness. This
research was developed to study the influence of coir fiber and kenaf fiber in
problematic soil in terms of road work purposes. First, the geotechnical
properties of soil were studied to classify the soil type. Natural fibers were
prepared in two conditions which are untreated sample and treated with 5%
sodium hydroxide (NaOH) sample before mixing with soil. To confirm the
alteration of morphology of the fibers, scanning electron microscope (SEM) test
was performed. Furthermore, the mechanical properties of natural fiber-soil
mixture were assessed. Direct shear test, consolidation test and California
Bearing Ratio (CBR) test were carried out on original soil, untreated fiber- soil,
and treated fiber-soil. The results revealed that the tensile strength of both
fibers was increased after being treated with sodium hydroxide. The inclusion
of untreated and treated fibers into soil has increased the optimum moisture
content (OMC) and decreased the maximum dry density (MDD). The rate of
consolidation for reinforced soil increased and resulting in lower value of rate of
volume compressibility. The strength of soil was increased up to 48% when
reinforced with untreated coir fiber. For soil reinforced kenaf fiber, the strength
increased 29.6% with untreated kenaf fiber and 35.5% with treated kenaf fiber. The results of CBR values for unsoaked and soaked condition were increases
as the inclusion of fibers for all mixed samples. According to Arahan Teknik
Jalan 5/85, the minimum requirement of CBR value for subgrade layer is
5% and all samples of soil reinforced coir fiber and kenaf fiber, achieve the
minimum value. Overall, the properties of soil used have been identified and
classified as organic clay with high plasticity. The inclusion of coir fiber and
kenaf fiber improved the geotechnical properties of soil in terms of settlement
behavior and shear strength. Natural fibers increased the CBR values up to
109% in unsoaked condition. In conclusion, all objectives have been satisfied
and it can be said that natural fiber had influenced the properties of soil in
terms of its shear strength, settlement and CBR values. |
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