The mechanical properties of asphalt mixtures are evaluated by triaxial test. The elements of the surface of pavement close to the tire-edge are affected with confining pressure due to wheel load. Therefore, triaxial test is applied for the evaluation, which can measure the strength constants and draw the stress-strain curve on various confining pressure at high temperatures. The failure strength of pourus asphalt mixture is smaller than dense-graded asphalt mixture on which rutting normally tends to grow more than on pourus asphalt concrete pavement. Thus, the rutting mechanism of different mixture types is not explained by triaxial tests under the same condition.
On the other hand, the volume-strains vs. axial-strain curves of the both types behave in different ways. In the case of a dense-graded asphalt mixture, the curve has its peak point on volume-compression condition. While the other, pourus asphalt has the one on volumeexpansion condition.