Engineering characterisation of Louisiana's asphaltic concrete mixtures using the indirect tensile test has been the focus of a recent comprehensive research program sponsored by the Louisiana Transportation Research Centre. Large variations in test results were observed between similar specimens. These variations were attributed to variable aggregate orientation, compaction procedure, and the test device. A new indirect tension test device was fabricated locally and used to reduce the test variability. The repeatability and performance of the new indirect tension device was evaluated. A statistically designed test factorial was used to examine the variation between the existing and the modified test devices. Mechanical tests were conducted for indirect tensile strength, diametral resilient modulus, and indirect tensile creep. The effects of the test devices, deformation measurement system, and operator error on the mechanical properties - as measured from the indirect tensile strength, resilient modulus, and creep modulus - of a specific asphalt concrete mixture are presented. The results of the test program indicated that both test devices provided repeatable results; mechanical properties were not significantly different due to operator error; mechanical properties measured with the modified test device were significantly different than those measured with the existing test device; and the modified test device can capture the temperature effect on the resilient modulus better than the existing test device. (Author/publisher)
Abstract