Rheological characterization of storage-stable SBS-modified asphalts

Abstract

The high-temperature storage stability of styrene–butadiene–styrene triblock copolymer (SBS) modified asphalt can be improved significantly with the addition of elemental sulfur. The dynamic mechanical properties of SBS-modified asphalts before and after adding sulfur were characterized by using dynamic shear rheometry. The addition of sulfur to SBS modified asphalt resulted in the formation of a chemically vulcanized SBS network structure in the modified binders, and the high temperature performance of the binders was improved and their temperature susceptibility was reduced to a great extent. The SBS content has a great effect on the rheological properties of the asphalts. The rheological properties of SBS modified asphalts depended strongly on the sulfur level. Increasing sulfur levels led to increasing crosslinking density in the modified binders, and consequently the rheological properties of SBS-modified asphalt was improved. A comparison was made among the properties of the asphalts modified by three different SBS structures. The SBS structure affected the compatibility and storage stability of SBS-modified asphalts, which were improved by the addition of sulfur. As determined by a rotational viscometer, the increase in asphalt viscosity is not directly proportional to the SBS content before and after adding sulfur. The morphology of SBS-modified asphalts, which was characterized by optical microscopy, showed that the compatibility and storage stability of SBS modified asphalt were improved by the addition of sulfur.