APPLICATIONS OF INNOVATIVE MATERIALS FOR PERFORMANCE IMPROVEMENT OF FLEXIBLE PAVEMENT OVER EXPANSIVE SUBGRADE

Abstract

Expansive soils are one of the most problematic materials that are widely encountered in
significant land areas in several parts of the world; like Africa, Australia, India, United States and Canada.
The South Gujarat region in India have majority of top soil as black cotton soil. The black cotton soil has
characteristics of shrinking on drying and heaving on wetting. This soil being expansive creates several types
of damages to pavement structures, and in some cases the pavement may even become unserviceable. The
normal climate condition of study area shows short wet and long dry period which aggravate the problem of
swelling and shrinkage. The IRC: 37 – 2001, Annexure – 4 suggest 0.6 to 1.0 m thick non-cohesive soil
cushion on the expansive soil for road construction which led to higher cost for road construction. Also for
new urban areas it is difficult to raise the embankment or to excavate the subgrade upto such a depth due to
existing structures and under laying service lines. To provide economical solution along with feasible
application two innovative materials were used namely, CONSOLID and Geotextile for flexible pavement.
The CONSOLID application shows the great improvement of CBR values helping the overall stability of the
pavement. The Geotextile provided below the pavement components to act against the heaving of the
swelling soil at the same time it helps as drainage layer also. Field study is undertaken to observe the effect
of Geotextile in flexible pavement performance and 2 specific boundary conditions are created for
observations. The Observations shows about 50 % reduction in shrinkage effect for paved road reinforced
with Geotextile subjected to drying and wetting cycles. Both the materials are having its unique advantage in
the performance improvement of flexible pavement over expansive subgrade.