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This paper presents laboratory test results demonstrating the effects of aggregate type and gradation on fatigue and permanent deformation of asphalt concrete. Diametral fatigue tests and uniaxial incremental static creep tests were performed under varying temperatures and mixture variables, including aggregate type and gradation.
The effects of aggregate type and gradation on permanent deformation were evaluated under test combinations with changing asphalt type, asphalt content, air voids content, temperature, and applied stress level. For the fatigue study, the effect of aggregate type was evaluated by changing asphalt content, air voids content, and temperature. The test results were analyzed using statistical analysis and graphical comparison of data. The analysis of variance (ANOVA) tests were performed to investigate the main effects and interactions of the test variables with the aggregate type or gradation.
The analysis revealed that, with the size of experimentation used in this study, aggregate type has significant effects on fatigue resistance and permanent deformation of asphalt concrete, indicating better performance from the mixtures comprised of aggregates with a rough surface texture and an angular shape. Coarse gradation, meaning a larger proportion of coarse aggregates with the same nominal maximum aggregate size compared to medium gradation, did not show significant effects on permanent deformation. Interactions of aggregate type with gradation, asphalt type, air voids, and temperature were found to be significant for the permanent deformation of asphalt concrete, whereas no interaction appeared to be significant for fatigue with the given size of experimentation.
aggregate type, gradation, fatigue, permanent deformation
Assistant Professor, North Carolina State University, Raleigh, NC
Graduate Research Assistant, North Carolina State University, Raleigh, NC
Professor, North Carolina State University, Raleigh, NC