Abstract: Beam fatigue tests are commonly used to evaluate the fatigue characteristic of asphalt mixture around the world.2PB is widely used in Europe while more application of 4PB is found in USA. The two test methods are compared in test standards, specimen requirement, specimen aging condition, test conduction and application of test results. The conclusions are drawn that: 2PB is more complex in specimen preparation, demands more accurate geometry and more sophisticated test equipment, but the specimen is more homogeneity and representativeness than 4PB. Specimen cluing, fixing and replacing during the test is more time-consuming in 2PB test, making the test operation more complicated, also the maximum loading strain is no more than 500με in 2PB test. In contrast the specimen fixing and replacing, loading strain adjustment can be achieved by software controlling in 4PB test, making 4PB test an easy operation, also the maximum loading strain can be about 2 000με. More specimens are required to obtain a fatigue curve of in 2PB than that in 4PB, time-consuming in 2PB is more than double of that in 4PB. Fatigue life of 2PB test can be regarded as real fatigue of pavement in situ because of the observed cracks cross specimen after test but the fatigue life of 4PB test is conservative. Fatigue life variation of 2PB is smaller than 4PB. Test results of 2PB can be used for comparison as well as an input parameter in pavement design, results of 4PB can be only used for HMA comparison.

Key words: highway engineering, hot-mix asphalt；beam bending fatigue test；2PB；4PB

摘要： 小梁疲劳试验是广泛应用的沥青混合料疲劳试验方法，两点梯形梁疲劳试验（two-point trapezoidal beam fatigue test,2PB）主要在欧洲应用而四点弯曲小梁疲劳试验（four-point bending beam fatigue test,4PB）在美国应用广泛。从试验标准、试件要求、老化条件、试验操作和结果应用等方面进行2PB与4PB的对比，指出2PB试验中试件成型复杂，试件尺寸精度要求高，对设备要求复杂，但试件具有较好均匀性和代表性；4PB试件成型较简单，试件尺寸易满足。2PB试件黏附、固定、更换费时，操作上繁琐一般最大加载应变500με；4PB试验中试件固定、更换、调整应变等直接通过软件实现，操作容易，最大加载应变可达到2 000με。2PB疲劳试验试件数要求多，获取疲劳曲线试验周期为4PB试验的两倍以上。2PB试验后试件表面可见裂纹，测量结果对应混合料的实际疲劳寿命而4PB测量疲劳寿命结果较保守。2PB疲劳结果离散性小于4PB结果，2PB结果可用于混合料疲劳性能评价以及作为路面设计输入参数，4PB结果仅用于混合料疲劳性能的评价。

关键词: 道路工程, 沥青混合料, 小梁疲劳试验, 2PB, 4PB