Strength and rutting characteristics of asphalt pavements in Manitoba

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Thiessen, Myron
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This research investigates the strength and rutting performance of in-service asphalt pavements in Manitoba using a simple, modified version of the static indirect tensile (IDT) strength test. The aim of the research is to evaluate the strength and deformation properties of asphalt mixtures and relate these fundamental properties to observed rutting behaviour in the field. This represents a significant shift from traditional mix evaluation methods, which rely primarily on mix volumetric properties and empirically based tests, such as Marshall stability and flow, to assess rutting resistance. Experience gained in this area will serve to help in the selection of suitable mix designs that are more resistant to rutting. Cored samples were collected from ten representative highway sections across the province with varying age, traffic, and rut depth characteristics. Twenty-one cores were obtained from each pavement section: three from both the inner and outer wheel paths and 15 from the area between wheel paths. The cores were obtained from three randomly selected areas within each pavement section. Mix volumetrics and binder properties were determined from 12 of the core samples while three samples per site were tested for strength and performance parameters. Performance of the samples was determined using a modified form of the static indirect tensile strength test at 25oC. The specimens were loaded diametrally at a loading rate of 0.1 mm/minute until failure occurred. Miniature LVDTs mounted directly on the central portion of the sample measured the lateral and axial deformations while a load cell captured the strength data continuously throughout testing. Simple regression analysis was employed to relate the rutting data from each pavement...