利用汉堡轮轨试验进行平衡配合比设计

这篇客座文章由范寅博士撰写. He is an Assistant Research Professor at the National Center for 沥青 Technology at Auburn University. 在他的允许下，我们在这里分享它，但可以找到原文  在这里.

The Hamburg Wheel Tracking Test (HWTT) per AASHTO T 324 is widely used by asphalt researchers and pavement engineers to evaluate the rutting resistance and moisture susceptibility of asphalt mixtures. According to a recent NCAT survey of state highway agencies and the asphalt pavement industry, 14 states currently require the HWTT in their provisional or standard specifications for asphalt mix design. 在这些州中, six use the HWTT as a pure rutting test while the rest use it as a combined rutting and moisture damage test. 另外, t在这里 are seven states that have selected the HWTT as a performance test for balanced mix design (BMD) and are currently conducting research to benchmark existing mix designs or develop preliminary performance criteria for BMD pilot or shadow projects.

典型的HWTT车辙深度曲线包括压实后阶段, 蠕变阶段, 有时是剥离阶段. Traditional HWTT parameters include total rut depth (TRD) at a certain number of wheel passes, 蠕变斜率, 剥离坡度(SS), 剥离拐点(SIP). T在这里 is a consensus among the existing literature that TRD and CS are often used to evaluate the rutting resistance of asphalt mixtures, 而SS和SIP主要用于水分敏感性评价.

多年来, asphalt researchers have proposed alternative HWTT parameters to improve characterization of the rutting and moisture resistance of asphalt mixtures. 这些可选参数包括修正车辙深度(CRD), 抗车辙指数(RRI), 剥离数(SN). CRD represents the projected HWTT rut depth caused only by permanent deformation of the mixture, which is isolated from the rut depth due to the stripping of asphalt binder from the aggregates. RRI is calculated based on the rut depth and number of wheel passes at completion of the test, 它允许直接比较HWTT结果与不同的测试终止点. A normalized RRI (NRRI) can also be used to account for different criteria dependent on binder grade. SN，作为SIP的替代水分敏感性参数 , is defined as the inflection point of the HWTT curve fitted with a three-parameter deformation model. It represents the maximum number of wheel passes that the mixture can resist in the HWTT before stripping occurs.

Although most of the traditional and alternative parameters can identify asphalt mixtures that are extremely susceptible to rutting and/or moisture-related distresses, little information is available as to how they correlate to actual pavement field performance. 认识到这一局限性，NCAT和德州农科院的研究人员&M 运输ation Institute (TTI) collaborated on a study w在这里 they compiled a HWTT database with test results of over 70 plant-produced mixtures. 这些混合物是从几个NCHRP项目评估的17个实地项目中收集的, 一个LTPP测试段, 以及NCAT测试轨道上的测试路段. 在过去的10年里，HWTT测试一直在NCAT和TTI实验室进行. The database was then analyzed to determine the correlation of various HWTT parameters to field performance data and estimate the within-laboratory repeatability of HWTT rut depth measurements.

The correlation evaluation of HWTT rutting parameters was conducted using 17 mixtures from the NCAT Test Track. The analysis results indicated that the RRI and CS parameters showed the best correlation to pavement rut depth measured after 10 million ESALs of heavy truck traffic (R ² = 0.924和0.881)，其次是CRD (R ² = 0.586)，然后TRD在20000次(R ² = 0.283). The field correlation of HWTT moisture susceptibility parameters was evaluated based on a receiver operating characteristic (ROC) analysis, 使用数据库中的所有混合物. ROC分析, 简单描述, assesses the degree of correspondence between the HWTT results and field performance that is qualitatively categorized as either ‘with moisture distress’ or ‘without moisture distress’. ROC分析鉴定出9,000和2,000作为SIP和SN的最佳标准, 分别. 然而, these criteria should be used with caution because they were developed with a limited number of mixtures with signs of moisture damage in the field and thus, 需要进一步的实验室和现场数据验证. 最后, the within-laboratory repeatability of HWTT rut depth measurements was determined largely in accordance with ASTM C670. 两个HWTT复制之间车辙深度测量的最大允许差异(e.g., 同一次跑步的左轮和右轮的结果, 或同一轮两次单独运行的结果)计算为2.3, 3.9, 4.6、4.在5,000,10,000,15,000和20,000轮次时，TRD分别为7mm. 因此, it is recommended that the two sets of HWTT replicate results with a difference greater than these allowable differences should not be accepted.

除了这些NCAT/TTI研究的研究结果, another recommendation for consideration by states interested in adopting HWTT for BMD is to use a standardized data analysis program (or software) for mix design approval and/or production acceptance. 确保承包商和代理结果的一致性, specific instructions should be provided regarding the number and locations of deformation readings (along the track length) used for data analysis and the calculation of selected test parameters, 等.

A good example for reference is provided by the Iowa Department of 运输ation in Matls IM 319 at iowadot.gov /话务量/经常/ IM /内容/ 319.htm.

Details about the development of alternative HWTT parameters can be found in the following issues of 交通研究记录:交通研究委员会期刊.

阴,F., E. Arambula R. 立顿,. E. 马丁和L. G. Cucalon. Novel Method for Moisture Susceptibility and Rutting Evaluation Using Hamburg Wheel Tracking Test. No. 2446, 2014, pp. 1-7.

温,H. F., S. H. 吴,我. N. 穆罕默德,W. G. 张,年代. H. Shen, and A. 作出贡献. Long-Term Field Rutting and Moisture Susceptibility Performance of Warm Mix 沥青 Pavement. No. 2575, 2016, pp. 103-112.

阴,F., C. 陈,R. 西,. E. 马丁和E. Arambula-Mercado. Determining the Relationship Among Hamburg Wheel-Tracking Test Parameters and Correlation to Field Performance of 沥青 Pavements. No. 2674(4), 2020, pp. 281-291.

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