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Modification of Dynamic Modulus Predictive Models for Asphalt ...

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Figure 14: Measured Values vs. Predicted Values <strong>of</strong> <strong>Dynamic</strong> <strong>Modulus</strong> on log-log Scale<br />

(Mix/Laydown condition) [31]<br />

The results indicate the Witczak model well simulates the trend <strong>of</strong> dynamic modulus values.<br />

The best fitting lines parallelly deviate from the lines <strong>of</strong> equality. By applying a multiplier or<br />

shift factor <strong>for</strong> each method, the Witczak model showed high accuracy on predicting dynamic<br />

modulus values <strong>for</strong> Florida mixtures. It should be noticed that using DSR test results to estimate<br />

a binder’s viscosity results in lower predicted dynamic modulus values.<br />

Argentina Study [32]<br />

Materials studied in this research contain both lab produced mixtures and field cores. Field<br />

cores were taken from 17 sections around Rosario in the Littoral region <strong>of</strong> Argentina containing<br />

42 types <strong>of</strong> mixtures. Eight laboratory mixtures were designed and compacted to sample<br />

cylinders using Marshall Procedures. Lab data were used to evaluate the 2000 Witczak model,<br />

the Hirsch clarify model, and the Heukelomp and Klomp equation developed in 1964. Figure 15<br />

through Figure 18 show the dynamic modulus values predicted by the Witczak and Hirsch<br />

models versus laboratory results on log-log scale <strong>for</strong> lab produced mixtures and field mixes,<br />

respectively.<br />

37

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