How do geosynthetics improve pavement's performance

Experimental and analytical investigations were conducted to evaluate the performance of geosynthetic reinforced flexible pavement sections. Geosynthetic materials were incorporated in the pavement systems at the bottom of the base layers. Eighteen pavement sections, constructed at a test facility, were tested. The pavement sections were constructed to model a typical secondary road in Virginia which is built over a week granular (silty sand) subgrade material; two California Bearing Ratios (CBR) were evaluated. The base material was 21-A crushed granite used at two different thicknesses, 15 cm and 20 cm. Loading of the pavement sections was accomplished through the use of a computer-controlled pneumatic system which delivered 552 kPa through a 30-cm diameter rigid plate at a frequency of one-half Hertz. The resulting displacement of the pavement surface was monitored by an array of linear variable displacement transformers (LVDTs). The study concluded that the geosynthetics can provide substantial improvement to the performance of a pavement section constructed on a low CBR subgrade. The reinforcing mechanisms of geogrids and geotextiles are different, with separation mechanism (provided by geotextiles) being an important factor in reinforced pavement performance. The study also showed quantitative improvement in service life and cost savings when geosynthetics are incorporated in the pavements.