Case Study: Chip Seal Program in Oregon
Summary
This presentation will summarize performance and the methodology used for developing specifications and a rational chip seal design in Oregon. Test sections included both emulsified asphalt and hot applied chip seal applications. The pre and post construction pavement performance information is presented and analyzed. Post-construction analysis of the chip seals includes macrotexture analysis, dynamic friction testing to measure microtexture and pavement performance surveys. The underlying pavement conditions were classified from being very good to very poor performance. In this study, a comparison of field performance on test section is developed to recommend best practices and develop a rational design methodology.
The results of the study showed that a performance-based specification for chip seals was possible. Implementation of this work is being funded by the Federal Highway Administration State Transportation Innovation Council (STIC) grant and additional funding by the Oregon DOT.
Introduction
Chip seals are an effective preservation strategy that extend the life of the pavement. The success of a chip seal and pavement preservation program can depend on many factors but specifications play a large role in determining overall performance of the seal. This research investigated the performance of 14 chip seals in various regions throughout Oregon under a range of climates and traffic conditions. Seals were constructed with both emulsified asphalt and hot-applied asphalt. Laboratory evaluation of the aggregate materials was investigated and the field performance of the seals was monitored for bleeding, chip loss, macrotexture and the reoccurrence of underlying pavement distresses.
Webinar Objectives and Outline
The Oregon chip seal research was conducted in two phases. The Phase I objectives were to:
- Document and evaluate methods of chip sealing,
- Report the performance of chip seals,
- Apply chip seal design, and
- Identify best practices for implementation.
The webinar will present results from the Phase I which include: material properties of chip seal aggregates, performance comparison between hot asphalt and emulsified asphalt chip seals, and which chip seal performance metrics worked well for performance evaluation. The webinar will also present the Phase II objectives and discuss the development of a chip seal performance specification.