Xingyuan Qin

With the increase in traffic load, the rutting problem of bitumen pavement appears more and more frequently, and the shear resistance of pavement has attracted more and more attention. A polymer-modified bituminous mixture is usually used to solve the problem of insufficient shear resistance in bitumen pavement. However, there are many polymer modifiers for bituminous mixture, which lead to different performances of the modified bituminous mixtures. Currently, the modification methods cannot obtain a bituminous mixture having all types of performance simultaneously. Therefore, considering the different performances and economics of modified bituminous mixtures, it is necessary to determine an optimal modification method for bitumen pavement. This study used a toll plaza in Jilin province, which is a seasonally frozen region. On this section of road, vehicles start and brake at high frequency, and the bitumen middle course suffers from large shearing forces. Therefore, permanent deformation is the main form of failure. In addition, low-temperature cracking of the bitumen pavement is also a very severe issue in this region. Four kinds of bituminous mixture modification schemes were selected and tested, and the pavement performance of these modified bituminous mixtures was evaluated. The fuzzy comprehensive evaluation method was used to quantitatively evaluate the performance level of bituminous mixtures according to fuzzy logic theory. Using the actual situation of the bituminous mixture used in the toll plaza, and based on the analytic hierarchy process method, the weight matrix of each service attribute was established. Here, the weight of each index was calculated by combining the entropy weight (EW) method, reducing the influence of subjective factors. According to the evaluation result of the fuzzy comprehensive evaluation model, it could be seen that the modified bituminous mixture (70^#+M) had the best overall performance compared to the other bituminous mixtures.

In order to ensure smooth traffic and driving safety, deicing salt or snow melting agents are usually adopted to solve the problem of traffic jams and prevent pavement surfaces from freezing. The objective of this present study is to investigate the performance deterioration evaluation of asphalt mixture under the chloride salt erosion environment. Five chloride salt solution concentrations were designed and the uniaxial static compression creep test, low-temperature IDT test, freeze-thaw splitting test, and freeze-thaw cycle test were carried out for asphalt mixtures (AC-16) soaked in chloride salt solution. Results showed that with the increase in chloride salt solution concentration, the high-temperature stability, low-temperature crack resistance, and water stability of the asphalt mixture decreases. Moreover, the high-temperature stability, low-temperature crack resistance, and water stability of the asphalt mixture show a decreasing trend under different chloride salt solution concentrations following the negative cubic polynomial function. Based on the viscoelastic analysis, chloride salt solution could reduce the ability of the asphalt mixture to resist instantaneous elastic deformation and permanent deformation, and this influence will become more obvious with the increase in chloride salt solution concentration. In addition, the salt freeze-thaw cycle test indicated that in the early stage of freeze-thaw cycles, the splitting tensile strength of the asphalt mixture decreases rapidly, then tends to be flat, and then decreases rapidly. This study explores the performance damage law of asphalt mixture under salt corrosion, and the analysis results of this study could provide some references for the chloride salt dosage in the snow melting project while spreading deicing salt.

The subgrade is the foundation of railway construction, so its strength and stability are very important to ensure the safety and stability of a train. Loess is widely distributed in northwestern China, and it must be stabilized before being used in railway subgrade construction because loess is sensitive to water. Railway subgrade withstands not only the train load but also repeated attacks from the environment and climate because it has to be exposed to natural environment after construction. Therefore, the strength of cement-stabilized loess deteriorates continuously because of the above factors. Taking account of long-term stability, the influences of load on the cement-stabilized loess as well as the strength reduction laws of cement-stabilized loess under wet–dry cycling and freeze–thaw cycling were analyzed in this study. Additionally, the respective reduction coefficients were obtained. Finally, the strength design criteria of cement-stabilized loess subgrade were put forward based on railway subgrade durability by analyzing the obtained reduction coefficients and the critical dynamic strength of railway subgrade.