Nonwoven Geotextile Interlayers for Separating Cementitious Pavement Layers Use in Germany Leads to Better Practice in Us

Nonwoven geotextiles between cementitious layers have been part of the design and construction of concrete pavements in Germany since 1981. German experience with nonwoven geotextile interlayers includes the design and construction of unbonded overlays and new pavement. German pavement engineers recognize that nonwoven geotextile interlayers provide three specific functions that are beneficial in concrete pavement systems (i.e., unbonded overlays and new pavement): separation, drainage, and bedding between layers. These functions help minimize the risk for reflective cracking and the potential for pavement damage caused by pumping and erosion. Over the years, German engineers have studied and refined nonwoven geotextile material specifications and construction methods in order to maximize the performance of the interlayer and the longevity of the pavement system. The use of nonwoven geotextile interlayers between cementitious layers in concrete pavements, while practiced for nearly three decades in Germany, is a new and innovative concept for the U.S. Recent economic trends have caused many U.S. contractors to explore alternatives to hot-mix asphalt (HMA) interlayers, and as a result, an interest in applications of nonwoven geotextiles similar to those in Germany is gaining momentum. In 2009, publications by the U.S. Department of Transportation Federal Highway Administration (FHWA) and the National Center for Concrete Pavement Technology (CP Tech Center) introduced the U.S. paving community to initial material recommendations and better practices for construction based on German experience (Hall et al., 2008; Rasmussen and Garber, 2009; CP Tech Center 2009). This paper documents the German experience from which better practices for using nonwoven geotextile interlayers between cementitious layers were developed. This paper also presents initial U.S. implementation efforts in the States of Missouri and Oklahoma, and discusses future goals for U.S. implementation of nonwoven geotextiles as a competitive alternative to HMA interlayers in concrete pavement systems.