躺滴法表征沥青的表面自由能

 表面自由能是用来确定沥青材料自身的黏聚功（黏聚强度）以及沥青与石料之间的黏附功的重要参数。此外，沥青混合料（包括沥青、石料和空气）的水敏感性也可使用沥青与石料的表面自由能参数进行评价。笔者采用躺滴法测定了几种战略公路研究计划(SHRP)沥青与液体的静态接触角，使用Owens-Wendt法确定了沥青的表面自由能。结果表明，躺滴法得到的沥青表面自由能与由接触角得到的数值比较接近，说明可以应用躺滴法来测定沥青的表面自由能。由沥青的表面自由能表征的沥青黏聚能结果与pull-off强度试验结果相吻合。

DETERMINATION OF THE SURFACE FREE ENERGY OF ASPHALT BINDERS BY SESSILE DROP METHOD

The surface free energy is an important parameter that can be used to estimate the cohesion work (cohesive strength) of asphalt binders and the adhesion work between the asphalt binder and aggregates. In addition, the surface free energy characteristics of water may be mathematically combined with the surface free energy values of the asphalt binder and the aggregates to assess the moisture susceptibility of asphalt mixture, which is composed of graded aggregates, asphalt, and air voids. The sessile drop method was employed in this study to measure the static contact angle between several strategic highway research program (SHRP) asphalt binders and probe liquids. From these measurements, the surface free energies of the asphalt binder were estimated by the Owens-Wendt method. The surface free energy results of the sessile method for the different asphalt binders were similar to the results measured by contact angle method, giving credence to the applicability of this method for evaluating different types of asphalt binders. The cohesion work of asphalt binders, which is described by surface free energy, was in agreement with that obtained from pull-off tensile strength.