Addition of rejuvenating oils to aged, dry asphaltic pavement materials to restore them to their original condition is a practice currently being used on many construction projects. Typically, the effect of rejuvenation is measured using standard mix design procedures such as stability. This research was aimed at providing information on the behavior of rejuvenated mixtures when subjected to accelerated aging such as repeated freezing and thawing and sustained high temperature. The nondestructive resilient modulus (MR) test was used to monitor the change in recycled mix from an old pavement, new mix made with virgin asphalt, and old mix rejuvenated with two commercially available admixtures. Results indicated that old mixtures continued to age rapidly and the rejuvenated mixtures behaved similarly to virgin mixtures.
The Oregon Department of Transportation (ODOT) has undertaken research into polymer modified asphalt binders in hot mix asphalt (HMA) with the expectation that such binders have the potential to provide more cost-effective, long-lasting asphalt concrete pavement. The research has involved three field installations with control sections of conventional asphalt and a laboratory study. Modifiers used in field installations were ethylene-vinyl-acetate (EVA), styrene-butadiene (SB), and styrene-butadiene-rubber (SBR). This paper discusses ODOT's research efforts with polymer modified HMA, and summarizes the findings of this research. ODOT's adoption of the Pacific Coast Conference on Asphalt Specifications' “Performance Based Asphalt Cement Specifications” is the next logical step based on knowledge gained from these research efforts.
This paper is part of an experimental investigation of the resilient properties and the stress-strain relationship of asphalt treated base material. It describes the triaxial testing system which was designed for this purpose and the different tests employed in the material stress-strain characterization.
This paper evaluates and discusses the development of fatigue cracking in several test pavements and inservice pavements. Attention is focused on the cause and development of fatigue failure in the field. Examples are shown for several types of asphalt pavements including those with aggregate, asphalt treated, or cement treated base. Failure is described in terms of crack initiation through several possible mechanisms and crack propagation to the ultimate stage of alligator cracks. Discussion is presented as to the implications of fatigue failure with respect to design life. Computations and analysis show that a thick asphalt pavement may not resist complete fatigue failure any better than a pavement of the same thickness which was built in “stages,” if the overlay is applied before cracking occurs.
Conventional liners and covers for solid waste storage are typically constructed of multiple layers of compacted clay and flexible membranes to prevent undesirable leachate from entering the ground water system. An effective alternative is a system of asphalt concrete to provide a strong and durable impermeable liner system with one or more layers. Polymer modification of the asphalt binder provides the ability to increase binder content for impermeability without sacrificing flexibility and strength. The benefits of these materials were demonstrated in the construction of a liner for incinerator bottom ash near Bellingham, Washington.
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