Mechanical Characterization of Superpave Gradation between Passing through and below Restriction Zone

10.6135/ijprt.org.tw/2013.6(5).539

Tung-Wen Hsu；Wen-Kai Yang；Jian-Xun Wang

Dynamic Modulus Test ； Indirect Tensile Creep Compliance and Fracture Energy Test ； Semi-circular Bending Test ； Superpave Level 1 mix design

International Journal of Pavement Research and Technology

6卷5期（2013 / 09 / 01）

539 - 546

英文

Mechanical characterization of the Superpave gradations passing through and below the restriction zone is presented through a series of strength tests, which include semi-circular bending test, dynamic modulus test, indirect tensile creep compliance test, indirect tensile fracture energy test, and triaxial shear strength test. The investigation is firstly to get these two different aggregate structures using Superpave Level 1 mix design method. The optimum asphalt content for the gradation mixtures passing through and below the restriction zone are 5.0% and 4.7%, respectively. The test specimens which were blended at the optimum asphalt content for each gradation mixture were prepared and compacted at four percent of void ratio using Superpave Gyratory Compactor. The Marshall mix design property results indicate that the higher stability values, indirect tensile strength and flow values are observed for the gradation mixtures passing through the restricted zone (TRZ gradation). It appears that these mixtures might possess better resistance against fatigue cracking and less resistance against rutting compared to the gradation mixtures passing below the restricted zone (BRZ gradation). Moreover, the TRZ gradations exhibit the higher fracture toughness in the semi-circular bending tests, the lower exponential values in the creep compliance tests, and the higher fracture energy in the indirect tensile strength tests. All results indicate that the TRZ gradations could have a better capability against fatigue cracking. However, the BRZ gradations reveal the higher dynamic modulus observed at longer reduced time in the dynamic modulus master curves, the more reduced time required to reach the same strain in the repeated loading triaxial tests, and the slightly larger value of φ obtained in the triaxial shear tests, all illustrate their superior performance against rutting. Based upon these experimental results, it can be stated that the TRZ gradations exhibit better resistance against fatigue cracking, whereas, the BRZ gradations possess greater performance in rutting resistance.