Geosynthetics with enhanced lateral drainage capabilities in roadway systems

While moisture-induced distress is one of the major causes of premature pavement failure, geosynthetics are only seldom used to provide internal drainage within the structure of roadway systems. This is likely because conventional geosynthetic drains are only suitable to manage flow under saturated soil conditions, whereas unsaturated conditions prevail in pavement systems. Recent insight into the interaction between geosynthetics and unsaturated soils has led to new advances in geosynthetic manufacturing, including the development of geotextiles with enhanced lateral drainage (ELD), which allow drainage even under unsaturated conditions. This paper highlights the benefits of ELD in a number of roadway situations, including: (1) enhanced lateral drainage of moisture migrating upward from a high water table, (2) enhanced lateral drainage of moisture infiltrating downward from the surface, (3) control of frost heave-induced pavement damage, (4) control of pavement damage caused by expansive clay subgrades, and (5) enhanced lateral drainage in projects involving soil improvement. The mechanisms of moisture migration, as well as the impact of ELD are evaluated in each of these situations. Additionally, case histories involving recently constructed pavements involving the use of ELD geosynthetics are presented for each specific drainage application. The selected case histories involve post-construction evaluation of the ELD geosynthetic's performance either through assessment of lateral drainage, condition surveys of pavement sections with and without ELD geosynthetics, or in-situ monitoring of moisture content. Assessment of the data collected illustrates the beneficial impact of ELD used in the various pavement scenarios. Overall, this paper illustrates that incorporation of enhanced lateral drainage in roadway systems results in a range of improvements for pavement performance.