To overcome the liquid set dependency of existing surface free energy (SFE) component approaches, this paper presents an Equation-of-State (EQS) approach to measure the SFE of bituminous binders. A succession of water-ethanol mixtures with varying surface tensions are first prepared as the test liquids. The Wilhelmy plate method is then adopted to measure the surface tension γ_L of each liquid as well as the contact angle θ between bituminous binder and each test liquid. A quadratic polynomial function is subsequently employed to fit the plot of γ_Lcosθ versus γ_L. Combining Young’s equation and Good’s interaction parameter and then imposing a limiting condition in which the contact angle between bituminous binder and test liquid is exactly 0°, the SFE of a bituminous binder can be finally determined. This approach is verified to have capability to accurately measure the SFE of bituminous binders with a solid thermodynamic basis.

为了克服现有表面自由能（SFE）组分方法对液体凝固的依赖性，本文提出了一种状态方程（EQS）方法来测量沥青结合料的SFE。首先准备一系列具有不同表面张力的水-乙醇混合物作为测试液体。然后将威廉米悬片法，采用以测量表面张力γ_大号每种液体以及沥青粘合剂和各试验液体之间的接触角θ。二次多项式函数随后被采用以适合的γ情节_大号COSθ与γ_大号。结合杨氏方程和古德的相互作用参数，然后施加一个极限条件，即沥青粘合剂与测试液体之间的接触角正好为0°，即可最终确定沥青粘合剂的SFE。经验证，该方法具有以固体热力学基础准确测量沥青粘合剂的SFE的能力。