Development of a Test Method to Measure the Quality of Milling Operations in Asphalt Pavements

Cold milling operations have been used for more than two decades in Indiana, but little attention was given to the quality of the operations. Several alternatives for evaluating surface macrotexture were considered as a quality measure. ASTM E965-96 was selected as the best procedure on which to base evaluation of milled surfaces. The Indiana Department of Transportation developed Test Method ITM 812-03T to make the ASTM procedures workable for milled surfaces. The initial quality of hot-mix asphalt (HMA) construction directly affects the long-term performance and the service life of a transportation facility. It is directly dependent on the quality of the aggregates and binders and the production and laydown operations. Construction concerns include surface preparation, which is the removal of distressed materials to develop a stable working platform on which HMA materials can be placed. Indiana HMA contractors were experiencing numerous problems in meeting volumetric and density quality requirements on highway construction projects. A significant number of HMA mixtures were either being accepted with partial payment or replaced before being accepted. Investigation of the problem included observing the contractor's certified HMA plant production operations, mixture components (i.e., aggregates, binders, etc.), mixture transportation, laydown and compaction, and mixture sampling procedures. It was discovered that more problems occurred when cold milling of the existing surface was included in the project. A solution to these issues resulted in the development of improved milling design and construction requirements, which include quality measurement techniques for the milling operations.

Ranking Loci for Genetic Stock Identification by Curvature Methods

Measures of the utility of loci in genetic stock identification problems are usually not based on the method of maximum likelihood, which is the actual statistical procedure used to estimate stock contributions. We present a general procedure, derived from the likelihood method, for assessing the utility of baseline data. The method depends on the curvatures of potential likelihood surfaces and can be used prior to mixture sampling. We also develop a real time implementation of a curvature measure and apply it to simulated mixture samples. The error in likelihood estimation depends on the amount of variation in genotype frequencies between reference samples as well as the location of the center of that variation. The curvature measure accounts appropriately for both factors and, in addition, is able to quantify the synergistic interaction of multiple loci. The curvature approach and simulation results are also applied to the problem of sampling allocation.