Comparative Evaluation of Field and Laboratory-Produced Foamed Asphalt Mixture from Reno, Nevada
Civil and Environmental Engineering
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This study evaluated the properties and performance of field-produced HMA and foamed WMA mixtures from the Bravo Ave project in Reno, Nevada in comparison to respective laboratory-produced mixtures utilizing the same materials and mix design. Each mixture contained 15% RAP and was produced with a polymer-modified PG64-28NV asphalt binder. The rheological properties were evaluated for virgin, RAP and extracted/recovered asphalt binders from field and plant-produced mixtures. The mixtures were evaluated for their resistance to moisture damage by means of measuring the dynamic modulus |E*| and the indirect tensile strength as a function of multiple freeze-thaw cycling. The resistance of the mixtures to permanent deformation was evaluated through the use of the repeated load triaxial (RLT) to measure the flow number (FN). The low-temperature cracking resistance of the mixtures was evaluated using the thermal stress restrained specimen test (TSRST). From this study it was determined that the HMA had better resistance to moisture damage and permanent deformation than the foamed WMA mixtures. Between the HMA and foamed WMA mixtures, similar asphalt properties and resistance to thermal cracking were seen. The laboratory-produced mixtures did not exhibit similar behaviors as those seen with the field-produced mixtures. Also, reheating of the mixtures from an ambient temperature after mixing seems to only improve the resistance of the mixtures to moisture damage. The non-reheated mixtures had equal or better resistance to permanent deformation and thermal cracking than their reheated counterparts.