Recommendations for Extending Asphalt Pavement Surface Life within Washington State

This study identified and evaluated hot mix asphalt (HMA) mix design and construction techniques that have potential for improving pavement surface life in Washington state.

Hot mix asphalt (HMA) pavement performance in Washington state varies across the state’s three broad climatic zones. In Western Washington, the climate is classified as mild marine, and the average surface life of WSDOT pavements is 16.7 years. In Eastern Washington, which has hot, dry summers and cold winters, the average surface life of WSDOT pavements is 10.9 years. In the mountain passes, with harsh, cold, wet winters, the average surface life of WSDOT pavements is as low as 5 years, which is likely a combination of mixture choice, structural design, construction practices, and climate impacts.

WSDOT pavements tend to fail first by cracking. The Washington State Pavement Management System (WSPMS) indicated that, statewide, cracking is the first to reach critical thresholds that require resurfacing 86 percent of the time, whereas rutting thresholds are reached first only 13 percent of the time. However, rutting plays a more substantial role as traffic levels increase. This is especially true in Eastern Washington, where studded tire use can more than double the rate of rutting.

The researchers evaluated and prioritized the application of 17 construction techniques to improve pavement life in Washington’s climate zones. In general, they concluded that WSDOT should focus most intently on techniques to improve pavement cracking resistance. For all but high-volume pavements, this generally involves techniques that increase asphalt binder content, reduce surface aging, and use additives. However, for high-traffic and mountain pass pavements, improved rutting, raveling, and studded tire wear resistance should be priorities; they generally require specialty mix designs and additive use.

The 17 evaluated techniques were the following: avoiding late season paving; increasing longitudinal joint density; mitigating temperature differentials with a density profile and with Pave-IR; using intelligent compaction; using warm mix asphalt as a compaction aid; applying non-Superpave aggregate gradation; reducing the Ndesign; using a 3/8-inch nominal maximum aggregate size, polymer modified asphalt, rubberized asphalt, the addition of lime, stone matrix asphalt, or steel slag aggregate; conducting performance testing on rutting and stripping; conducting performance testing on cracking; and applying a bituminous surface treatment within one year of paving. Because this study was not intended to be an intensive laboratory investigation, evaluation relied on corroborating multiple data sources, including a literature review, department of transportation survey, the WSPMS, laboratory tests, case studies, and cost analysis.

WA-RD 860.1

Haifang Wen
Skyler Chaney
WSU Department of Civil and Environmental Engineering

Stephen Muench
UW Department of Civil and Environmental Engineering

Kevin Littleton
Tim Rydholm
Washington State Department of Transportation

Sponsor: WSDOT
WSDOT Project Manager: Lu Saechao