Currently, pavement designs are primarily related to structural rehabilitation treatments or reconstruction of existing pavements. Past and current design techniques require characterization of the in-situ elastic modulus properties of the materials contained in the pavement structure. The two primary ways to characterize these material properties for in-situ unbound material layers are through the interpretation of deflection measurements or laboratory tests on material samples obtained from the field. It has been conclusively established that the results from backcalculation of deflection measurements do not always match the results from laboratory tests on samples obtained in the field, even when comparable stress states are matched. Evidence suggests that the way field samples are prepared and tested in the laboratory can affect modulus-based test results as compare to in-situ tests.
During construction of new and reconstructed pavement structures, field compaction control of unbound materials has historically been based on density measurements as a percentage of laboratory determined optimum. Some types of newer compaction equipment use a modulus-based feedback mechanism to control field operations. The relationship between density, maximum density, elastic modulus, resilient modulus, backcalculated modulus, and moisture content as it applies to pavement design, field compaction, and pavement performance justifies further research.
The primary objective of this research is to establish relationships between material properties determined through field tests and those from laboratory test on field samples contained within the LTPP database for pavement design and performance prediction purposes.
The objectives of this research are to: (1) establish relationships for resilient modulus among samples prepared by the following three methods: lab mixed-lab compacted, field mixed-lab compacted and field mixed-field compacted; (2) establish relationships among other material properties (Atterberg Limits, LA Abrasion, sand equivalent, soundness, gradation, moisture content, etc.) for samples obtained from aggregate stockpiles at the materials production site, from haul vehicles and from the pavement before and after compaction; (3) establish relationships, if any, from DCP and FWD backcalculated modulus field data; and (4) establish the impacts of the differences in field and laboratory determined unbound material properties on MEPDG pavement performance prediction models.