Fracture toughness of polymer-modified asphalt concrete at low temperatures

The fracture toughness of asphalt concrete increases at low temperature and then decreases at temperatures below a certain level. Some polymers are known to have the property of improving the temperature susceptibility of asphalt binder at low temperatures. Therefore, this study evaluated the fracture toughness (K IC ) of some polymer-modified asphalt concretes. Low-density polyethylene (LDPE), styrene–butadiene–styrene (SBS), and a mixed polymer of LDPE and SBS were used in this study. The fracture toughness K IC of normal asphalt concrete was compared with that of polymer-modified asphalt (PMA) concrete, and the effectiveness of polymer modification against falling values of K IC was evaluated at low temperatures. The results showed that PMA concretes, in general, showed better K IC than normal asphalt concretes, and the temperature at which the highest K IC was obtained was lower than that in the case of normal asphalt concrete. Therefore, the PMA concretes evaluated in this study had better fracture resistance than normal asphalt at low temperatures.Key words: asphalt concrete, polymer-modified asphalt, PMA, fracture toughness, differential thermal contraction, low-temperature damage.