HIGH VOLUME/HIGH SPEED ASPHALT ROADWAY PREVENTIVE MAINTENANCE SURFACE TREATMENTS

The South Dakota Department of Transportation (SDDOT) has made extensive use of chip seal and sand seal surface treatments in the maintenance of their asphaltic concrete (AC) pavements. Such surface treatments have been found to provide a cost-effective means of extending the life of AC pavements in South Dakota. Although the use of chip seals and sand seals have for the most part been reliable treatments, there have been some notable failures, especially on high-volume, high-speed roadways. This project was undertaken to investigate the use of chip seals for such applications and to make recommendations to improve their performance. This project also involved the development of guidelines for the design and construction of chip seals. To evaluate the use of chip seals in South Dakota, several efforts were undertaken. First, an extensive literature review was conducted to develop an understanding of the latest practices and experiences. Second, interviews were conducted with SDDOT from all departments involved in the chip seal process to investigate their practices and to determine areas for improvement. Finally, test sections were constructed to evaluate the performance of standard and modified chip seal designs. The test sections consisted of 12 chip seal designs and included two aggregate types (quartzite and natural aggregate) and alternate chip seal designs with new gradations and other modifications and enhancements. Based on these efforts, recommendations are provided to improve chip seal performance. In addition, guidelines were developed to select feasible surface treatments for a specific project.