The design of hot recycled asphalt mixes with high RAP content, say more than 25%, as per existing guidelines is complex compared to the conventional Hot Mix Asphalt (HMA) design. This is due to the fact that the mix design requires the properties of bitumen in the RAP material and hence, it involves using solvents to recover the bitumen and testing of the recovered bitumen using sophisticated equipment. Considering the issues associated with bitumen recovery procedure that were reported in the literature and the practicalities involved in testing the recovered bitumen, the present study aims to identify indices that can reasonably estimate the RAP characteristics without the need to recover the bitumen. For this purpose, two tests namely, the Fragmentation test and Cohesion test that were proposed by the RIlEM Technical Committee 237-SIB committee for RAP classification for cold mix design were evaluated. These two tests can be conducted using conventional apparatus used for quality control tests that are available at most of the field laboratories. Fragmentation test was carried out on six different RAP sources and at three different conditioning temperatures (5°C, 20°C, and 40°C). Cohesion test was carried out on RAP from five different sources at five conditioning temperatures (70°C, 100°C, 140°C, 170°C, and 190°C). The test results suggest that the index derived from fragmentation test (S_frag) correlated well with the physical properties of recovered bitumen such as penetration, softening point, and complex shear viscosity. Further, the index was able to estimate the difference in % of fines in black and white curves. The sensitivity of the air voids and Indirect Tensile Strength (ITS) of the Marshall specimen (S_{air voids} and S_ITS) obtained from the cohesion test correlated well with bitumen content and bitumen type respectively.

与传统的热拌沥青 (HMA) 设计相比，根据现有指南，具有高 RAP 含量（例如超过 25%）的热回收沥青混合料的设计是复杂的。这是因为混合设计需要 RAP 材料中沥青的特性，因此，它涉及使用溶剂来回收沥青并使用复杂的设备对回收的沥青进行测试。考虑到文献中报道的与沥青回收程序相关的问题以及测试回收沥青所涉及的实用性，本研究旨在确定无需回收沥青即可合理估计 RAP 特性的指标。为此，进行了两项测试，RILEM 技术委员会 237-SIB 委员会提出的用于冷拌设计的 RAP 分类的碎裂试验和凝聚试验进行了评估。这两个测试可以使用用于质量控制测试的常规设备进行，这些设备可在大多数现场实验室获得。在六种不同的 RAP 源和三种不同的调节温度（5°C、20°C 和 40°C）下进行碎裂测试。在五个调节温度（70°C、100°C、140°C、170°C 和 190°C）下对来自五个不同来源的 RAP 进行内聚力测试。测试结果表明，该指数来源于碎片测试（这两个测试可以使用用于质量控制测试的常规设备进行，这些设备可在大多数现场实验室获得。在六种不同的 RAP 源和三种不同的调节温度（5°C、20°C 和 40°C）下进行碎裂测试。在五个调节温度（70°C、100°C、140°C、170°C 和 190°C）下对来自五个不同来源的 RAP 进行内聚力测试。测试结果表明，该指数来源于碎片测试（这两个测试可以使用用于质量控制测试的常规设备进行，这些设备可在大多数现场实验室获得。在六种不同的 RAP 源和三种不同的调节温度（5°C、20°C 和 40°C）下进行碎裂测试。在五个调节温度（70°C、100°C、140°C、170°C 和 190°C）下对来自五个不同来源的 RAP 进行内聚力测试。测试结果表明，该指数来源于碎片测试（S _frag ) 与回收沥青的物理特性（如渗透、软化点和复剪切粘度）有很好的相关性。此外，该指数能够估计黑白曲线中的罚款百分比差异。从内聚力测试中获得的 Marshall 试样（ S _{air voids}和S _ITS ）的气孔敏感性和间接拉伸强度（ITS）分别与沥青含量和沥青类型密切相关。