Research on the Anti-Reflective Cracking Performance of a Full-Depth Asphalt Pavement

In order to analyze the anti-reflective cracking performance of a full-depth asphalt pavement and study the propagation process of a reflection crack and its influencing factors, a mechanical model of pavement structural crack analysis was established based on the ABAQUS finite element software and the extended finite element method (XFEM). Based on two different loading modes of three-point bending and direct tension, the propagation process of a reflection crack is analyzed. The results show that the anti-reflective cracking performance of a full-depth asphalt pavement is better than that of a semi-rigid base pavement structure, and the loading mode II based on direct tension is more consistent with the propagation mechanism of pavement reflection cracks, while the loading mode II is more suitable for analyzing the anti-reflective cracking performance of the pavement structure. Appropriately reducing the elastic modulus of the stress-absorbing layer can significantly improve the anti-reflective cracking performance of the full-depth asphalt pavement.

Research on Shrinkage Chemical Properties of Cement Stabilized Macadam Material Based on a Multi-dimensional Expansion and Shrinkage Tester

In order to find out the shrinkage law of cement stabilized macadam material under specific conditions, this paper studied the expansion and shrinkage properties of cement stabilized macadam material under two environmental conditions, five kinds of cement dosage conditions, suspended compacted type and skeleton compaced type based on the multi-dimensional expansion and shrinkage tester. Through the test comparison, it is confirmed that the water loss rate of cement stabilized macadam material increases with the increase of cement dosage, showing a general change rule of rising first and then stabilizing. The average increase of the total water loss rate of suspended compacted cement stabilized macadam at room temperature was greater than that of the skeleton compacted cement stabilized macadam. The dry shrinkage strain also follows the above trend. Either at room temperature or under the conditions of dry shrinkage box, the water loss rate of suspended compacted cemeny stabilized macadam is higher than that of skeleton compacted cement stabilized macadam , which can be up to 3.23% higher. By comparing the temperature shrinkage coefficient under the high and low temperature environment, the temperature coefficient of the skeleton compacted cement stabilized macadam is smaller than that of the suspended compacted cement stabilized macadam. The temperature shrinkage coefficient of the suspended compacted cement stabilized macadam increases by 5.56% on average for each 0.5% increase of the cement dosage, and the temperature shrinkage coefficient of the skeleton compacted cement stabilized macadam increases by 6.33% on average. Through the comparative analysis of tests, it can be found that the anti-reflection crack ability of the skeleton compacted cement stabilized macadam material is better, and the fine aggregate content should be strictly controlled in the construction.

Study on the Main Characteristics of Reflective Cracking in the Asphalt Overlay on an Old Cement Pavement

The purpose of this study is to explore the forms and characteristics of reflection crack in asphalt overlay of old cement pavement, so as to provide reference for effective prevention and treatment of reflection crack.By means of ANSYS finite element software, considering the coupling effect of temperature and vehicle in different working conditions, the influence of cooling on asphalt overlay was analyzed, and the location and form of crack were discussed.The analysis results show that tensile crack and shear crack are more likely to occur near the joint of old cement pavement, and shear crack is more likely to occur in areas outside the joint, about 1/2 wheel length from the joint of cement pavement.The prevention and treatment of crack at different locations should be carried out according to different working conditions.

Research on Improving Shrinkage Performance of Cement Stabilized Gravel with Waste Rubber Particles

Cement stabilized gravel has good characters like high strength, good stability, anti-erosion properties and better anti-fatigue property, but it is easy to produce desiccation cracks when humidity changes (caused by evaporation), resulting in reflection crack on the bituminous pavement surface, and then influences performance and the service life of the pavement. Along with the changes in traffic conditions, seme-rigid asphalt concrete pavement meet the two major challenges as early damage and heavy traffic. It has significant economic and social significance that support a method of construction and conserve of seme-rigid pavement which accommodate heavy traffic highway and has guidance and reference value in other conditions.It is analyzed by comparison between the performances of mixture with best amount of admixture which obtained by shrinkage test and mixture without admixture.