Application of SCB Test and Surface Free Energy Method in Evaluating Crack Resistance of SBS Modified Asphalt Mixes

Cohesion properties of the binder matrix within asphalt mixes and adhesion characteristics of the asphalt binder and aggregate particles are the two major mechanisms resisting against cracking in asphalt mixes. This study is focused on estimating crack resistance of asphalt mixes at intermediate temperatures through evaluation of cohesion and adhesion properties of binder-aggregate systems using Surface Free Energy (SFE) method. Semi-Circular Bending test (SCB) was used to support the SFE analysis. SFE measurements were performed applying Sessile Drop test method. A Granite aggregate type and two asphalt binders (PG64-16, PG58-22) containing various amounts of SBS polymer were used to produce six groups of asphalt mixes. Cohesion and adhesion energies obtained from SFE analysis and Flexibility Indexes and Fracture Energies determined in SCB test showed the positive effect of SBS on performance of asphalt mixes at intermediate temperatures, although the effectiveness of SBS modification was more pronounced with SCB parameters. A linear regression was performed and a strong correlation was observed between SFE results and SCB parameters.