124 RECENT INNOVATIONS AND PRACTICES OF PAVING FABRIC SYSTEMS TO REDUCE REFLECTIVE CRACKING Farshad Amini Professor & Chair Department of Civil & Environmental Engineering Jackson State University Jackson, MS 39217-0168 USA e-mail: famini@jsums.edu ABSTRACT Pavement rehabilitation is rapidly becoming one of the most important issues facing many highway departments. Asphalt concrete overlay is one of the commonly used methods for rehabilitating deteriorated pavements. One major type of distress influencing the life of an overlay is reflective cracking. Reflective cracking in the overlay allows water to percolate into pavement structure and weaken subbase, and contributes to many forms of pavement deterioration, including increased roughness and spalling. Although these nonwoven fabrics have generally been successful in asphalt overlay applications, there is no synthesis to their performance. In the past, the role of paving fabrics to reduce reflective cracking has not been clearly evaluated. As a result, there is a lack of consistent considerations of paving fabric option in pavement management systems. In this project, applications and effectiveness of stress-relieving interlayers, known as paving fabrics, to reduce reflective cracking is synthesized. Basic functions of paving fabrics, long-term performance, and recent innovations are discussed. In addition, a survey of the current paving fabric applications in the State of Mississippi was conducted to determine the various practices and performances of the paving fabric systems to reduce reflective cracking. The field performance of overlays using fabric interlayers has generally been successful, although there have been cases where the paving fabric systems provided little or no improvements. A summary of state-of-the-art practices as well as possible directions for future research is reported. INTRODUCTION When an overlay is placed on existing pavement, physical tearing of the overlay occurs because of movement at the joints and cracks in the underlying pavement layer. Temperature- associated horizontal movement of the slab, concentrated in underlying joints and cracks in the existing pavement, lead to tensile stresses, and is an important contributor to reflective cracking. Some of the treatment techniques that are used to reduce or prevent reflective cracking include reinforcement of overlay (steel wire mesh, expanded metal, fabrics such as polymer grids, and glass grids), increased thickness of asphalt overlay, asphalt mix additives (such as polymer, sulfur, and dry lime), bond breakers at joints of pavements, and the use of stress absorbing interlayers such as paving fabrics (e.g., Barksdale, 1991; and Jackson, 1980). The nonwoven geotextile interlayer systems, known as the paving fabrics, can be used to reinforce asphalt overlays by carrying tensile stress, and possibly shear stresses caused by environmental or traffic loading, and usually provide a waterproofing barrier. Studies have indicated that the cost of reflective crack control treatments is usually very high (e.g., Buttlar et al., 2000). Some literature suggests that 1