Title: A LABORATORY INVESTIGATION INTO THE EFFECTS OF AGGREGATE-RELATED FACTORS ON CRITICAL VMA IN ASPHALT PAVING MIXTURES (WITH DISCUSSION)
Abstract: This research focused on the volumetric state of hot-mix asphalt (HMA) mixtures as they transition from stable to unstable configurations. This has traditionally been addressed during mix design by meeting a minimum voids in the mineral aggregate (VMA) requirement, based solely upon the nominal maximum aggregate size without regard to other significant aggregate-related properties. The goal was to expand the current specification to include additional aggregate properties, e.g., fineness modulus, percent crushed fine and coarse aggregate, and their interactions. The work was accomplished in three phases: a literature review, extensive laboratory testing, and statistical analysis of test results. The results clearly demonstrate that the volumetric conditions of an HMA mixture at the stable-unstable threshold are influenced by a composite measure of the aggregate size gradation and by aggregate shape and texture. The currently defined VMA criterion, while significant, is seen to be insufficient by itself to correctly differentiate sound from unsound mixtures. Under current specifications, many otherwise sound mixtures are subject to rejection solely on the basis of failing to meet the VMA requirement. Based on the laboratory data and statistical analysis, a new paradigm to volumetric mix design is proposed that explicitly accounts for aggregate factors (gradation, shape, and texture).
Publication Year: 2001
Publication Date: 2001-01-01
Language: en
Type: article
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Cited By Count: 5
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