Effect of Material Composition on Cohesion Characteristics of Styrene-Butadiene-Styrene-Modified Asphalt Using Surface Free Energy

Styrene-butadiene-styrene- (SBS-) modified asphalts were prepared by mixing different base asphalts, SBS modifier, extracting oil, and stabilizing agents. The contact angles between SBS-modified asphalt and distilled water, glycerol, and formamide were detected by the sessile drop method. Based on the surface energy theory, the surface free energy and cohesive power of SBS-modified asphalt were calculated. The influence of the raw materials composition, such as the virgin asphalt and SBS modifier types as well as the extracting oil and stabilizing agent contents, on the cohesive characteristics of SBS-modified asphalt was discussed. The results showed that virgin asphalt was compatible with SBS modifiers to improve cohesiveness. The cohesive power of branched SBS-modified asphalt was larger than that of linear SBS-modified asphalt. The cohesion of SBS-modified asphalt was improved as the SBS modifier and stabilizer contents increased but was reduced for excessive extraction oil contents. The cohesive characteristics of the SBS-modified asphalt were improved by the formation of stable three-dimensional network structures by cross-linking, winding, and grafting among different raw materials.