Evaluation of Thin-Lift Overlay Pavement Preservation Practice: Mixture Testing, Pavement Performance, and Lifecycle Cost Analysis

Abstract

This study examines the practice of using thin-lift overlays (25-mm-thick asphalt) that was implemented recently for Nebraska’s highways by comparing it with the state’s traditional 5-mm-thick rehabilitation practice. The two overlay mixtures were acquired from actual paving projects on I-8 to conduct various laboratory tests, including the dynamic modulus test, dynamic creep test, semicircular bending fracture test, and Hamburg wheel tracking test. Based on the material’s characteristics obtained from the laboratory tests, structural performance analysis is conducted to compare the pavement performance with the two different overlay mixtures. In addition, a lifecycle cost analysis (LCCA) is performed to compare the economic benefits associated with the thin-lift overlay with those of the conventional overlay practice. Laboratory results show that the fine-graded thin-lift overlay mixture behaves similarly to the coarser-graded conventional overlay mixture in terms of mixture stiffness, rutting potential, and cracking resistance. The one exception is its resistance to damage caused by moisture. The simulation predicts that both pavements will perform satisfactorily during their expected design life, but the LCCA indicates that the practice of using the thin-layer preservation technique can reduce both the agency’s and users’ costs compared with the conventional 5-mm-thick rehabilitation practice. Good field performance from both overlay pavements is observed after 15 and 27 months open to traffic.