PERFORMANCE OF CONCRETE PAVEMENT WITH ECONOCRETE BASE

Abstract

In a study of a 16-mile three-lane section of Interstate 85 in Randolph and Davidson Counties, North Carolina, which opened to traffic in 1984, early signs of pavement distress were observed, particularly reddish-brown stains on the concrete shoulders due to water infiltration. This prompted an investigation to identify the sources of water infiltration, the path of water travel within the pavement system, and its impact on pavement performance. The study found that water infiltration occurred through joints and the concrete-soil interface at the edge of the concrete shoulders, exacerbated by the clay subgrade's dramatic volume change with moisture content variation. The longitudinal joints, formed by inserting plastic strips to create weak planes in the fresh concrete, and the econocrete base beneath the pavement facilitated water flow beneath the slabs, leading to hydrostatic pressure and pumping action from traffic loading. To address these issues, 5500 ft of shoulder drains were installed to evaluate their effectiveness in removing water from the pavement structure. The study resulted in recommendations for improving pavement designs, including the necessity of shoulder drains, the challenges of achieving perfectly sealed joints, the importance of proper dowel alignment, and considerations for the design and tie-down methods of dowel baskets. The findings led to changes in NCDOT's approach to concrete pavement design, emphasizing positive pavement drainage systems, sealing all joints, improving dowel basket design, and temporarily halting the use of econocrete bases. The study underscores the critical role of water management in pavement durability and the need for design adaptations to mitigate water-related damages. (Abstract generated by AI tool ChatGPT 4)