Effects of Aggregate Gradation and Angularity on VMA and Rutting Resistance
MetadataShow full item record
The Superpave system adopted the voids in mineral aggregate (VMA) criteria developed by McLeod using the 75-blow Marshall compactor for conventional dense-graded hot mix asphalt (HMA) mixtures. This VMA criteria is a function of only the nominal size of aggregate regardless of shape, texture, or gradation. The Superpave volumetric mixture design process contains a required minimum value for fine aggregate angularity (FAA) as a function of traffic level and position of the layer within the pavement structure. This parameter is reported as the percentage of uncompacted air voids, with larger values generally indicating increased aggregate angularity and, thus, higher VMA and better resistance to permanent deformation. The purpose of this study was to evaluate the effects of FAA and gradation on the resulting VMA of certain HMA mixtures. The effect of FAA was evaluated using mixtures containing coarse limestone combined with six different fine aggregates. Mixtures with three gradations which pass through, above, and below the restricted zone; three different mineral filler contents; and four different values of FAA were analyzed to evaluate the effects of these parameters on VMA of Superpave mixtures. Based on analyses of these tests, mixtures containing fine granite or limestone showed less permanent deformation than mixtures containing fine river gravel or natural rounded sand. FAA values and permanent deformation did not correlate well. Gradations that pass through the restricted zone did not significantly affect mixture VMA. Mineral filler contents and FAA value did affect mixture VMA significantly. Higher FAA values yielded higher VMA.
Showing items related by title, author, creator and subject.
Stutts, Zachary William (2012-05)Current Texas Department of Transportation (TxDOT) procedures for evaluating coarse aggregate for portland cement concrete (PCC) have been in place for over 39 years. Item 421 in the TxDOT "Standard Specifications for ...
An Experimental Study on the Guidelines for Using Higher Contents of Aggregate Microfines in Portland Cement Concrete Fowler, David W.; Ahn, Nam-Shik (2001-12)The use of manufactured fine aggregate (MFA) in portland cement concrete becomes more common as sources of natural sands are depleted. There is a great need to utilize MFA better, particularly the minus 75µm sizes. The ...
Weng, Yue, 1986- (2011-05)Online aggregation is a new trend in today’s world. It is developed from an IT concept to a much broader idea that applies to a variety of areas such as information, human capital, social power, and so on. The power of ...