Analysis of aggregate imaging system (AIMS) measurements and their relationship to asphalt pavement skid resistance

摘要

This thesis consists of two parts. The first part includes analyses of thecorrelation between the results of two Aggregate Imaging System (AIMS) units. Theseanalyses have led to refinements of the AIMS analysis methods of angularity andtexture, which resulted in reduced variability in the results and better correlation betweenthe two AIMS units. The refined analysis methods were used to establish a database ofthe shape characteristics of about 100 aggregate samples from the state of Texas and topropose a new method for the classification of aggregates based on their shapecharacteristics. This new method of classification is for use in the Texas Department ofTransportation (TxDOT) wet weather accident reduction program (WWARP). The useof AIMS texture index and variability in texture within an aggregate source is proposedinstead of the British Polish Value (BPV) for classifying aggregates used in pavementsurfaces.The second part of the thesis investigates the relationship between shapecharacteristics and asphalt pavement skid resistance. Many states have implemented wetweather accident reduction programs aimed at maintaining acceptable levels of pavement skid resistance. Proper aggregate selection before construction aids inmaintaining acceptable levels of skid resistance throughout the life of the pavement.Several predictive models of pavement skid resistance have been developed overthe years. Some of these models account for the influence of aggregate characteristicson pavement skid resistance, primarily through incorporating the results of the BPV testin the model. However, the BPV test is known to have high variability and dependenceon experimental factors that are not related to the actual aggregate resistance topolishing. AIMS offers a method to measure aggregate shape characteristics directly ina relatively short period of time. The new method for relating aggregate shapecharacteristics to pavement skid resistance was verified by relating skid resistancemeasurements from field test sections to measured aggregate properties from thelaboratory. This methodology is expected to be the basis for further study to form amore comprehensive and verified model for the prediction of pavement skid resistancethat incorporates measured aggregate properties from the AIMS system.