Chip seals have been successfully used on highways with traffic volumes in excess of 5, 000 vehicles per day. The performance life of those chip seals averages 6 to 7 years, with some applications lasting much longer. Unfortunately, a significant number of chip seals have not performed adequately. Some agencies refuse to use this potentially cost effective approach to pavement rehabilitation and maintenanceas a consequence. By developing a more fundamental understanding of the causes of chip seal failures on high traffic volume facilities, improved design methods, construction materials and methods, equipment, and specificationscan be developed. These improved procedures will form the basis of implementation packages that will encourage state highway administrations and other public agencies to utilize chip seals on high-volume pavements. Reasons for chip seal failure on high traffic volume facilities and methods that have been used to overcome these difficulties are described. In addition, methods are described for predicting potential adhesive qualities of chip seal binders by using a modification of the vialit procedure. Also, techniques are described for producing pressuredistributor nozzles that can be effectively calibrated, resulting in known binder distribution transverse to the centerline. These nozzles, which have been used on one experimental project, were produced to provide higher binder volume outside the wheelpaths. This paper appears in transportation research record no. 1259, Chip seals, friction courses, and asphalt pavement rutting 1990.
Abstract