Nondestructive Evaluation of Warm Mix Asphalt Through Resonant Column Testing

2014PDFTech ReportPSU-2012-02DTRT12-G-UTC03Nondestructive testsWarm mix paving mixturesShear modulusResonance frequencyProperties of materialsAsphalt mixturesAsphalt concreteResearch HubWarm mix paving mixturesNondestructive testsResonance frequencyPennsylvaniaUnited StatesMid-Atlantic Universities Transportation CenterKheiry, Pezhouhan TavassotiSolaimanian, MansourQiu, TongThomas D. Larson Pennsylvania Transportation InstituteUnited States. Dept. of Transportation. Research and Innovative Technology AdministrationUS Transportation CollectionNon-destructive testing has been used for decades to characterize engineering properties of hot-mix asphalt. Among such tests is the resonant column (RC) test, which is commonly used to characterize soil materials. The resonant column device at Penn State was used to determine the modulus and damping of warm-mix asphalt prepared with three different warm-mix technologies: water foaming, a waxy additive, and a chemical additive. Specimens were prepared in a Superpave gyratory compactor and then sawed and drilled to deliver the geometry needed for the RC tests. Hot-mix asphalt specimens were also tested to provide reference data. Testing was completed at 25 \ubaC. The RC device specimen assembly had to be retrofitted to make it suitable for testing asphalt concrete, which has a higher stiffness than soils at ambient temperatures. The results indicated that the RC test can be successfully used to determine the shear modulus of the asphalt concrete. Different torque levels, therefore inducing different strain levels, could be applied in the RC test to determine the range of linear elastic behavior of the material. This is an important step to ensure the validity of assumptions used for the purpose of modulus calculations. At 25 \ubaC, it was found that the lowest shear modulus was found for the mix prepared through the water foaming process, and the highest modulus was found for the mix with the waxy additive (Sasobit). The modulus of the mix with the chemical additive and the modulus of the hot-mix asphalt were found to be in between. Use of the RC test to determine the damping properties of asphalt concrete proved to be more challenging and strain dependent, even when maintaining the strain within the linear elastic range