ABSTRACT

Moisture sensitivity is one of the common distresses in flexible pavements due to the deteriorating effect of water on adhesion of bitumen-aggregate and cohesion of mastic. In the present study, the effect of the styrene–ethylene–butylene–styrene as bitumen modifier was examined on the moisture damage potential of control and modified asphalt mixtures using thermodynamic and mechanical methods. The results of this study indicated that the modified asphalt mixtures have significantly better resistance than the control samples. In addition, the results of the thermodynamic parameters showed that changes in the surface-free energy components of the modified bitumen have improved the adhesion of these bitumens to high silica aggregates that are susceptible to moisture. Moreover, the use of styrene–ethylene–butylene–styrene increases the surface-free energy of mastic film, which also increases the resistance to cohesion failure. Furthermore, the results of the amount of energy released during the stripping event show that the use of bitumen modifying polymer additive has reduced the amount of de-bonding energy. This indicates that the tendency for bitumen to detach from the aggregate surface in the presence of water has decreased from the thermodynamics view.

摘要

由于水对沥青集料的附着力和乳香的内聚力的恶化影响，湿气敏感性是柔性路面中常见的问题之一。在本研究中，使用热力学和机械方法检查了苯乙烯-乙烯-丁烯-苯乙烯作为沥青改性剂对控制和改性沥青混合料的水分破坏潜力的影响。本研究结果表明，改性沥青混合料比对照样品具有明显更好的抵抗力。此外，热力学参数的结果表明，改性沥青表面自由能组分的变化提高了这些沥青对易受潮的高二氧化硅集料的粘附力。而且，苯乙烯-乙烯-丁烯-苯乙烯的使用增加了乳香膜的表面自由能，这也增加了内聚破坏的抵抗力。此外，在剥离事件期间释放的能量量的结果表明，使用沥青改性聚合物添加剂降低了脱键能的量。这表明从热力学的角度来看，在水存在的情况下，沥青从集料表面脱离的趋势已经降低。