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This paper presents a comparative study of both laboratory and field performance of several applications of crumb-rubber modified (CRM) hot-mix asphalt in Louisiana. Eight CRM asphalt pavement sections were constructed using eight different CRM processes or applications. These eight CRM sections were built at five state highway projects. A control section with conventional asphalt mixture was constructed at each project to compare the performance of pavement sections built with CRM asphalt mixtures.To evaluate the mixture characteristics of the CRM and conventional mixes, laboratory tests of Marshall stability and flow, indirect tensile strength (ITS) and strain, and indirect tensile resilient modulus (M R ) were conducted on field compacted Marshall specimens.Comparisons of the field performances of the pavements were achieved through roadway core air void analysis, rut-depth measurement, international roughness index (IRI), pavement structure numbers measured through the DYNAFLECT system, and visual inspections of cracks.The result of this study indicated that the conventional mixtures exhibited higher laboratory strength characteristics than the CRM mixtures. The pavement sections constructed with CRM asphalt mixtures showed overall better performance indices (rut depth, fatigue cracks, and IRI numbers) than the corresponding control sections after five to seven years of traffic.

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