Sylvester Ampadu Asiamah
Published: 2002
Total Pages:
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ABSTRACT (cont.): Analysis of test results in this study indicate that excessive asphalt binder may have been used in order to meet the voids in mineral aggregates (VMA) criteria for the poor performing mixtures. This finding may be consistent with other related findings that suggest that for some coarse graded aggregate structures, addition of so much asphalt binder may be necessary to meet the current Superpave VMA specification. The VMA requirement should, therefore, be reviewed. It is also found in this study that for mixtures with excessive asphalt binder the aggregate structure may not significantly affect the rutting resistance of the mixture. This may be the case because the asphalt binder tends to have a predominant influence, especially at higher temperatures, reduces the aggregate particle interaction in the mixture and, therefore, leads to poor rutting performance. The study finds that there may be apparent relationships between rutting resistance of mixtures and the following laboratory measured parameters: (1) the rate of change of gyratory shear per cycle measured from the slope of the gyratory shear versus number of cycles (semi-logarithm scale) in the Servopac Gyratory Compactor, (2) the rut depth measured in the Asphalt Pavement Analyzer and (3) the gyratory stability index measured from the Gyratory Testing Machine.