沥青混合料疲劳性能试验与表征方法综述

针对沥青混合料疲劳耐久性设计参数的不确定性与不科学性问题，从疲劳试验方法及疲劳性能表征模型两方面对沥青混合料疲劳性能表征的发展现状、存在的问题进行了综述，并总结了其未来发展方向。沥青混合料疲劳性能主要通过室内外不同疲劳试验进行研究，不同试验方法所用沥青混合料试件的尺寸、形状，试件内部所处应力状态及试验条件皆各不相同，而沥青混合料是一种由沥青结合料与不同粒径矿料通过搅拌和碾压而成的多相、多组分、多尺度黏弹性混合料，其力学响应具有显著的时间、温度与应力状态相关性，不同试验方法所对应的加载速度、试验温度及应力状态存在较大的差异性，故其试验结果呈现出显著的不确定性，其疲劳性能表征模型参数也存在显著的差异性；此外，常用的室内材料疲劳试验方法大多为一维或二维应力状态下的疲劳试验，这与沥青路面结构实际服役过程中所处的三维应力状态不符；沥青混合料疲劳性能表征方程大多来源于一维应力状态下的疲劳试验结果，因此，用简单应力状态下的材料疲劳试验方法与性能表征模型难以客观表征三维应力状态下沥青路面结构的疲劳抗力，从而导致沥青路面疲劳耐久性设计存在较大的偏差。建议开发与沥青路面服役状态一致的三维应力状态下的疲劳试验方法，并建立三维应力状态下疲劳表征模型，以消除不同试验方法及试验条件对沥青混合料疲劳性能表征的影响，提高沥青混合料疲劳性能表征的有效性与完备性。

Test Methods and Characterization of Fatigue Performance of Asphalt Mixtures: A Review

The objective of this study is to analyze the fatigue and durability performance of asphalt mixtures. In this paper, previous studies conducted on fatigue test methods and the characterization of the fatigue properties of asphalt mixtures are reviewed, and the development direction is suggested. The fatigue properties of asphalt mixtures are usually evaluated through various laboratory and field fatigue tests. The test conditions adopted in the test methods, such as the size, shape, and stress state in the test samples differ and vary significantly. However, asphalt mixtures are viscoelastic materials with multiphase, multicomponent, and multiscale features, which are made of asphalt binders and minerals with different particle sizes through stirring and rolling. Their mechanical responses have significant time, temperature, and stress-state correlations. Significant uncertainties are observed in the test results obtained using different fatigue methods owing to the considerable divergence in the loading rate, test temperature, and stress state, and these factors further increase the differences in the model parameters of fatigue characterization. Moreover, laboratory fatigue tests were mostly conducted based on the one-dimensional or two-dimensional stress state, which is inconsistent with the three-dimensional stress state of asphalt pavements. The fatigue performance characterization equations of asphalt mixtures were typically established based on one-dimensional fatigue test results. A significant deviation in the durability design of asphalt pavements occurs because the fatigue test method and performance characterization model under simple stress-state conditions are used to reflect the actual fatigue resistance of asphalt pavements. It is recommended that three-dimensional fatigue test methods for a stress state consistent with the asphalt pavement service state should be developed. Additionally, the fatigue characterization of asphalt mixtures should be established to eliminate the effects of different test methods and test conditions on the fatigue properties, and thus, improve the validity and completeness in the fatigue performance characterization of asphalt mixtures.