Polyolefin Elastomer Modified Asphalt: Performance Characterization and Modification Mechanism

The rapid growth of traffic load and volume has put forward higher requirements for road durability. To extend the service life of roads, this work investigated the feasibility of using polyolefin elastomers with a two-phase molecular structure to simultaneously improve the high and low-temperature performance of asphalt. The characteristics of the polyolefin modifier were evaluated by differential scanning calorimetry first. Following evaluation, the storage stability, workability, and rheological properties of modified polyolefin-modified asphalt were measured through softening point difference, rotary viscosity, dynamic shear rheometer, and bending beam rheometer. Additionally, the engineering performance of modified asphalt mixtures was also investigated through Marshall stability, wheel-tracking, and three points bending experiments. The results show that polyolefin has two glass transition points which facilitate the simultaneous improvement of the high and low-temperature properties of asphalt. Meanwhile, no concerns are found about the storage stability and workability of polyolefin-modified asphalt. Furthermore, the results of rheological properties indicate that polyolefin can significantly enhance the deformation resistance at high-temperature and cracking resistance at low-temperature of asphalt binders. While the fatigue performance of the polyolefin-modified asphalt is slightly reduced, the residual Marshall stability, dynamic stability, and ultimate tensile strain of the asphalt mixture containing 8% polyolefin are 1.05 times, 1.31 times, and 1.17 times those of the control sample, respectively. The results of infrared spectroscopy demonstrate that there is no chemical reaction between the polyolefin-modified and the virgin asphalt. The improvement of polyolefin on asphalt performance can be explained by the existence of both “rigid” and “flexible” structures in polyolefin.

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