Effects of styrene butadiene styrene and Lucobite on stone mastic asphalt performance

This study evaluates the performance of stone mastic asphalt road paving mixtures modified with two polymer additives: styrene butadiene styrene and Lucobite. The test samples were made from limestone aggregate, pure bitumen 60/70 and polymer additives of 3 and 5% by weight. Penetration, softening point and rotational viscometer tests were conducted to assess the effects of additives on the physical properties of modified binders. Marshall stability, indirect tensile strength, moisture susceptibility, four-point beam fatigue, dynamic creep and wheel track tests were also performed to compare the performance of modified samples against an unmodified control sample. According to the test results, the additives improved binder performance and resistance against moisture, permanent deformation and fatigue compared with a conventional mixture. Based on the results, asphalt modified by styrene butadiene styrene had improved moisture sensitivity, permanent deformation performance (from wheel track tests) and fatigue behaviour up to 15, 32 and 53% better than unmodified asphalt, respectively. Lucobite-modified mixtures improved these properties up to 14, 20 and 40%, respectively.