Performance evaluation of encapsulated road pavement on difficult ground condition

This project focuses on a critical investigation into a novel development of the
road subgrade incorporating a pre-hydrated geosynthetic clay liner (RGCL) within a
proposed new Encapsulated Road Pavement (ERPS) design system for a Malaysian
difficult ground condition. It studied the effect of static loading on different reinforced
full scale road pavement model for six (6) months duration. Continuous full scale
testing was conducted at Research Centre for Soft Soil (RECESS Malaysia) located in
the campus site of Kolej Universiti Teknologi Tun Hussein Onn (KUiTTIIO). The test
area consists of very soft clay to a depth of 20 meters (JKR Malaysia, 1987).
The new RGCL is expected to act as a barrier that will encapsulate or 'wrap' the
imported subgrade layer in order to protect it from the high water table that exists in
most parts of the southern region of Malaysia (the state of Johor). Apart from acting as
a barrier to the existing sub-surface / ground water present at the test site, the RGCL
will also function as reinforcement in the road pavement system. The design and
application of RGCL is expected to reduce settlement and the effect of abrupt structural
failure to road pavement constructed on soft soil due to traff"ic loadings. It should
enhance the performance and prolongs the design life of the road pavement. Laboratory
tests on the soil properties and characteristics obtained from the test site were conducted
prior to the full-scale trial road embankment construction. Comparisons of different
design standards mainly the British and Malaysian Standards were made to understand
the current practiced rural road design concept. Full-scale trial road embankments were
instrumented with the state of the art monitoring facilities purchased from Canada
through fundamental research grants (Chapter 5: Field Instrumentation for full scale
research).
From this project, it may be concluded that rural roads when constructed on soft
clay with high water table, need to be reinforced and encapsulated with an impermeable
layer so that the subgrade layer may last longer as its intended design life. Water table
and rainfall intensity have an influence on road performance constructed on soft soil. It
was also found that the ERPS design system performs better or similar to the road when
compared to the unreinforced (Control Section) and geotextile-reinforced (Existing
Practice) road pavement respectively. However, further research such as long term
monitoring of this research project is recommended so that more concrete conclusion on
the behaviour and performance of encapsulated road pavement can be derived.
This project contributes in producing reliable, quality rural road pavement
design and construction on Malaysian soft soil. This will enable its inclusion into
current standards and assist in the construction of better and efficient rural road
networks whilst gearing the nation towards achieving the Malaysian Vision 2020.

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