ABSTRACT
In order to quantify the effect of geogrid stabilisation/reinforcement, a full-scale pavement field trial was established upon a soft and expansive subgrade. Sections with variable geogrid arrangements were constructed in order to allow the quantitative assessment of geogrid stabilisation/reinforcement; both in terms of their initial contribution to composite insitu stiffness parameters and their benefit to the long-term performance of a pavement. On site testing was completed within all trial sections during the project's construction phase, such that the initial state (strength and stiffness) of performance the subgrade and each pavement layer was adequately characterised. Post construction, ongoing performance monitoring has included the use of embedded pressure cells. An analysis of the first 3 years of monitoring of this full-scale field trial was conducted, with selected results presented herein. The data demonstrates that the inclusion of geogrids successfully improves the bearing capacity of the pavement profile by reducing the traffic imparted vertical pressures being exerted upon the underlying materials. The results also demonstrate that the presence of two geogrid layers (with one placed at the subgrade-subbase interface and one at the subbase-base interface) offer a greater improvement of the bearing capacity than the installation of a single geogrid at the interface of subgrade-subbase materials. Additional observations relate to longitudinal cracking of the pavement, where greater control of cracking has been initially achieved in the test sections where geosynthetic reinforcement was installed.
