The success of any seal coat depends not only on the quality of the binder and the aggregate (chips) but also on the compatibility of the two materials. Compatible binder-aggregate combinations will result in a long-lasting seal coat, and incompatible combinations will result in chip loss, bleeding, and so on. The use of additives in seal coats, whether applied to the binder or to the aggregate, has proved very useful in prolonging the life of a seal coat and improving its field performance. Polymer modified cutback (rc-3000r) and plain cutback (mc-3000) were used along with three different types of aggregate chips (blotter gravel (bg), pea rock (pr), and quartzite (q)) to determine the best binder-aggregate combination. Also, seal coats made with liquid asphalt were examined closely in terms of laboratory performance (using modified vialit test) and field performance (using an evaluation technique developed in south dakota). The rc-3000r andquartzite combination performed the best in the field and the mc-3000/bg combination was the worst. The field performance of test sections that were subjected to traffic for over 2 years resulted in a ranking of all test sections from 1 to6, with 1 being the best in performance. Two parameters extracted from the vialit test were found to have an excellent correlation with field performance--initial retention and the additional chip loss due to impact. This paper appears in transportation research record no. 1259, Chip seals, friction courses, and asphalt pavement rutting 1990.
Abstract