Research progress of long-life asphalt pavement behavior based on the RIOHTrack full-scale accelerated loading test

Abstract

Full-scale accelerated loading test is an efficient and effective method for simulating and studying long-term pavement performance because its loading and environment conditions are similar to those of real-world applications. In the past decades, this method has been recognized as an important support for the development of pavement design theory worldwide. In 2000, the long-life pavement was first presented by the researchers in Europe and the USA to obtain the most economical pavement during the whole life cycle. However, the completed design method of the long-life asphalt pavement has not been provided, especially for semi-rigid base asphalt pavement. In 2015, the Research Institute of Highway, Ministry of Transport constructed a 2.038-km-long full-scale field accelerated pavement testing track, which was named as RIOHTrack, to develop a long-life pavement suitable for China. The testing road has 25 asphalt pavement structure sections, and the average length of the testing section is 60 m. In all of the testing sections there were 19 structural testing sections, which are classified into six types, namely, the thin asphalt layer semi-rigid base pavement, the normal semi-rigid base pavement used in China, the composite pavement, the inverted pavements, the thick asphalt layer asphalt pavement, and the full-depth asphalt pavement respectively. In the first research phase, RIOHTrack planned to complete 50 million equivalent single axle loads ESALs (10 tons standard axle loading) by using trucks under the real environment. During the accelerated loading, two types of pavement performance detections were conducted. The first type is the real-time strain/stress responses and the environment information captured by the monitor sensors, and the other type is the periodic pavement performance detection measured by auto-detecting devices or artificial measures. In this paper, the bearing capacity, service performances, and inner mechanism responses under the couple of loading and environment were analyzed on the basis of the whole detecting data captured from December 2016 to January 2020. Four main conclusions were drawn. First, the influence of loading and environment on performance is considerably, and the influence degree of environment is even larger than that caused by the loading. Second, the pavement performance has structural dependence, the ranking of the six main types varies if evaluated using different performance indices, and the rutting depth prediction accuracy depends on the structural type. Third, the stress/strain monitoring results verify the nonlinear characteristic of asphalt pavement structure under the temperature and loading. To calculate the nonlinear effect in pavement behavior, a new mechanical analysis method was presented, which considers material and geometric nonlinearity theory. Lastly, to improve the prediction accuracy of the rutting depth, we utilized multivariate statistics to build the new prediction model based on the measured rutting depth data, and this model considers the changes in loading number and temperature change. The stage research results illustrate that the different type of pavement structure has its advantages and disadvantages, so the type of the long-life asphalt pavement should be multiple choice. China has the longest mileages of semi-rigid base asphalt pavements. Hence, long-life, semi-rigid base asphalt pavement building, and maintenance technology should be developed. More works should be carried out on mechanism analysis, prediction models, and failure criteria, and the accelerated loading test, such as RIOHTrack, will mainly provide support.