The concrete pavements that were originally constructed in Washington State as part of the interstate construction program have performed remarkably well considering the dramatic increase in the anticipated traffic loads. To date, the primary distress on the concrete pavements in Washington State has been in the form of joint faulting (due to lack of dowel bars and underlying base/subgrade conditions), longitudinal cracking (which is believed to have occurred 3 to 5 years after construction) and wear due to studded tires. A number of factors have contributed to the long-life of these concrete pavements, such as, short joint spacing (usually 15 ft – 4.6 m), thickness (8-9 inches, 200-225 mm) and aggregate quality. However, a number of design modifications have evolved over time to improve pavement performance. These include changes in the use of dowel bars, dowel bar type, mix design, hot mix asphalt base, joint design and joint spacing.
This research documents the design and performance of the concrete pavements built in the 1960’s, summarizes the design modifications and resulting pavement performance that has taken place over the last 40 years, summarizes current construction practices and discusses future challenges and risks for the long-life concrete pavements built in Washington State.