This study applies the Digital Image Correlation (DIC) technique to capture the displacement field on the specimen surface in the SC(B) fracture test of asphalt concrete for the construction of R-curves. Previous research, utilizing a displacement method, did not capture the micro-cracking that occurs during the formation of the cohesive zone in a fracture specimen. A Crack Opening Displacement Matrix (CODM) is defined based on the DIC displacement field. Five CODMs are used as alternatives of crack length extension to construct the displacement-based R-curve for asphalt concrete. The cohesive energies and energy rates are determined by those displacement-based R-curves. The influences of test temperature, loading rate, aggregate size, and polymer modification on cohesive energies and energy rates are then investigated. The following lists the major findings of the this study: (1) The cohesive energies determined by displacement-based R-curve are generally lower in value compare to the cohesive energy determined by crack-extension-based R-curve, which indicates the displacement-based R-curve and its cohesive energy may separate crack initiation and propagation by invisible micro crack; whereas the crack- extension-based R-curve separate the crack initiation and propagation by visible crack; (2) The test temperature is statistically significantly impacting on cohesive energies; loading rate is significantly impacting on cohesive energy determined by the R-curve using the CODM that is distant from the crack tip; (3) Higher loading rate, lower test temperature and larger aggregate size may lead to higher energy rate; but these trends are not statistically proved in this study. In all, the crack length and CODMs quantify the crack extension in different ways (length growing and wideness opening). Thus, by complementing the existing displacement-based R-curve, the R-curve system of both CMOD and CODM has the potential to fully characterize the fracture behaviour of asphalt concrete.

本研究应用数字图像相关技术（DIC）捕获用于R曲线施工的沥青混凝土的SC（B）断裂试验中试样表面的位移场。以前的研究，采用位移法，没有捕捉到在裂缝样本中形成粘性区的过程中发生的微裂纹。基于DIC位移场定义了裂纹开口位移矩阵（CODM）。使用五个CODM作为裂缝长度扩展的替代方法来构造基于位移的R形沥青混凝土R曲线。内聚能和能级由那些基于位移的R曲线确定。然后研究了测试温度，加载速率，聚集体尺寸和聚合物改性对内聚能和能量速率的影响。以下列出了本研究的主要发现：（1）与基于裂纹扩展的R曲线确定的内聚能相比，基于位移的R曲线确定的内聚能的值通常较低。基R曲线及其内聚能可以通过不可见的微裂纹将裂纹的萌生和扩展分开。基于裂纹扩展的R曲线通过可见裂纹将裂纹的产生和扩展分开。（2）测试温度在统计上显着影响内聚能；加载速率显着影响使用远离裂纹尖端的CODM的R曲线确定的内聚能；（3）较高的加载速率，较低的测试温度和较大的集料尺寸可能导致较高的能量速率；但是这些趋势在本研究中并未得到统计证明。总之，裂纹长度和CODM以不同的方式（长度增长和宽度扩展）量化了裂纹扩展。因此，通过补充现有的基于位移的R曲线，CMOD和CODM的R曲线系统都有可能充分表征沥青混凝土的断裂特性。