Abstract

In this work, the possibility of using non woven coir geotextile in soft subgrade soil was investigated.
Flexible pavement have mostly problems like formation of potholes, ruts, cracks and localized depression
and settlement. These are mainly due to insufficient bearing capacity of the subgrade. In the CBR method of
pavement design (IRC 37-2001), total thickness of pavement increases with decrease in the CBR value of
subgrade soil, which in turn increases the cost of construction. To achieve the economy and for proper
performance of roads, it is necessary to improve the strength of the soil. In this study, needle punched nonwoven coir geotextile material and adhesive bonded non –woven coir geotextile of varying densities were
utilized to improve the bearing capacity of subgrade. CBR tests were conducted on soil samples with coir
geotextiles of varying densities being interfaced between soft subgrade and unbound aggregate. In order to
evaluate the performance, the reinforcement ratio was obtained based on the CBR load- penetration
relation of both soft subgrade-gravel and soft subgrade-geotextile-gravel. Comparison of reinforcement
ratio showed that the performance of pavement was improved with inclusion of non-woven coir geotextiles.