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Dynamic Modulus of Asphalt Concrete Mixtures Using Small-Scale Specimens


The dynamic modulus of asphalt concrete (AC) mix is a primary engineering property that relates to the performance of AC pavements. This parameter is commonly measured using a cylindrical specimen having a 150mm height and a 100mm diameter (full-size specimens). This geometry is easy to obtain when a specimen is extracted from a laboratory-prepared gyratory sample, however, a gyratory sample does not represent an as-built asphalt pavement. Testing of the in-place AC pavement for the dynamic modulus, using the full-size cylinder specimens, is not possible because the required specimen height is greater than the typical AC lift thickness. In this study, the feasibility of using small-scale cylindrical specimens to measure the dynamic modulus of AC mixtures was investigated. Three different loose mixtures were obtained from the field. Specimens were extracted from laboratory prepared gyratory samples. Dynamic modulus test was conducted on two small-scale specimens having diameters of 38mm and 50mm, and a height of 110mm, in addition to the test on full-size specimens. A uniaxial hydraulic loading frame was used to test the specimens at various temperatures and frequencies. The test results from the small-scale specimens were found to be very similar to that of full-size specimens at low and intermediate temperatures. However, small specimens showed greater dynamic modulus values at a high temperature of 38°C in comparison to full-size specimens. The coefficient of variation for 38mm-diameter specimens was found to be higher than two other geometries.

Conference Paper Details

Session title:
Testing and Modelling of Road and Embankment Materials (S)
Hajibandezh, E., Shalaby, A., Ahammed, M.A., Liske, T.