Flat and elongated aggregates in Superpave regime

Some states have recommended changing the definition of hat and elongated a ggregates from 5:1 to 3:1 and an increase in the maximum allowable percenta ge of flat and elongated (F&E) particles to 20% or higher in the Superpave aggregate specification. Engineering justification and performance data are required to rationally establish the criteria for this change. The objecti ves of this research included the statistical analysis of performance indic ators of Superpave mixtures containing different levels of 3: 1 particles. Three mixes were designed and tested using 0, 15, and 40% of 3:1 particles from a set of Kentucky limestone aggregates. This paper contains the findin gs, conclusions, and recommendations on the research. The mixtures did not differ significantly in their performance-related properties at lower and h igher temperatures. However, at intermediate temperatures, significant diff erences were observed. A curve shifting analysis confirmed the presence of lower shear stiffness with an increase in the percentage of 3:1 F&E particl es. The mix densification trends were inconclusive. Additionally, at low te mperatures, the mixes with increasing percentages of 3:1 F&E particles seem ed to have higher tensile strengths. This particular finding needs to be Fu rther investigated. Overall, increases up to 40% of 3:1 F&E particles did n ot adversely affect the performance potential of such mixes as measured by the Superpave methodology.