摘要: |
Quality pavement foundation layers are essential to achieving excellent pavement performance. In recent years as truck traffic has greatly increased, the foundation layers have become even more critical to successful pavement performance. Unfortunately, there are still many pavement failures in the U.S. related to inadequate subbase, natural subgrade, and embankment (commonly referred to as foundation layers or roadbed). Factors that contribute to pavement foundation problems are believed to be poor construction practices, ineffective quality control/quality assurance (QC/QA) testing methods and sampling plans, material variability and unpredictable long-term material behavior, poor verification of material properties during construction, insufficient development of performance-related specifications, and low capital investment in the foundation layers. The objective of this research is to improve the construction methods, economic analysis and selection of materials, in-situ testing and evaluation, and development of performance-related specifications for the pavement foundation layers. The outcome of this study will be conclusive findings that make pavement foundations more durable, uniform, constructible, and economical. Although the focus of this research will be portland cement concrete (PCC) concrete pavement foundations, the results will likely have applicability to asphalt cement concrete (ACC) pavement foundations and, potentially, unpaved roads. All aspects of the foundation layers will be investigated including thickness, material properties, permeability, modulus/stiffness, strength, volumetric stability and durability. |