Applied Mechanics and Materials Vols. 361-363

Abstract: orthogonal test design approach is adopted to analyze and research several key factors like gravel drainage foundation layer strength, permeation coefficient, effective porosity to conclude the basic principle for indoor mixing ratio. On the basis of the indoor experimental achievements, the CTPB foundation layer of experimental road is designed and the test results show that the indexes reach the forecast effects.

Abstract: Based on theexamples works of the road site excavation pits channels and supplemented by road non-destructive testing methods, this paper mainly adopts the road performance of the structural layers , main site designated point FWD test, soil base DCP test and soil base structure bearing capacity correlation. The results show that the existing common road on FWD detection inverse soil base modulus has a good linear relationship with soil base DCP measured modulus, in addition, measured soil base modulus with moisture content of the soil base also have a good linear relationship, but the three correlation does not comply with the actual situation of the road. Thus, before the decision making of the highway overhaul conservation , old Road usage evaluation, the road of non-destructive testing, the excavation pits survey and structural layers indicators detection are very necessary and effective methods.

Abstract: With the development of chinas road construction, the increase of traffic and the traffic load the fatigue of asphalt pavement under the vehicle load has become one of the major disruption in the form of life of life of asphalt concrete directly affect the service life and the performance use of asphalt pavement ,it is a key factor to determine the life cycle cost of asphalt concrete pavement construction. The objectives of this paper are to characterize the fatigue behavior of porous asphalt pavement mixtures containing RAP and a WMA additive using Super pave gyratory compactor and dynamic modulus testing. Four types of asphalt mixtures were evaluated in this study. This study evaluated compaction energy index, permeability, indirect tensile strength, and dynamic modulus for all types of porous asphalt mixtures. All of the asphalt mixtures meet the typical minimum coefficient of permeability in this study.

Abstract: In order to reduce the soft soil layer deformation due to pavement construction, equal preloading of pavement is usually adopted after embankment filling in soft ground region. But as the ground treatment effect of pile-supported and geosynthetic reinforced embankment is satisfactory with great load-carrying ability, the necessity of applying equal preload is worth discussing. Combined with the practice of Guangzhou-Sanshui expressway widening project, the settlements in surveying sections during the paving construction period in extension area were monitored. The monitoring data shows that pavement load had small influence on embankment settlement: the uneven settlement between newly widen and existing road is small and the post-construction settlements are controlled within the standard requirement. On the premise of guaranteeing the construction quality of composite-foundation and filling compaction degree, it is unnecessary to take equal preloading to avoid excessive embankment settlement caused by the pavement structure.

Abstract: Combining with compression strength and tensile strength, the cohesive strength method is applied to determine the asphalt content (by weight of aggregate) of asphalt treated base (ATB) for the purpose meeting ATB tensile performance. The results are compared with those of Marshall Method. Two calculation methods of asphalt film thickness are applied to calculate the thickness of asphalt film. The calculation results show that cohesive strength method force the admixture to attain the better thickness of asphalt film, and the spectrum of film thickness is between about 6.5μm ~9.0μm.

Abstract: This paper used the design method of EME high modulus HMA from France to carry out the mix design of EME2(0/14) HMA, and carried out Duriez test, HWTD, dynamic modulus test and low temperature bending test. The test result showed that this kind of HMA had excellent water resistance, high temperature rutting resistance, high dynamic modulus and low temperature cracking resistance. This EME high modulus HMA was applied in the test road on Qing Lin expressway.

Abstract: Through conventional and unconventional tests, the influences of self-developed warm-mix agent on the performances of SBS modified asphalt are studied. The results show that the warm-mix agent has great influences on the ductility and aging quality changes of SBS modified asphalt; and the warm-mix agent can improve the asphalt rutting factor G*/sinδ and fatigue factor G* • sinδ. The mixing ratio of the warm-mix SBS modified asphalt mixture is designed based on GTM method and the pavement performance is compared and verified. The results show that: in terms of high temperature performance, the warm-mix asphalt mixture is superior to the corresponding hot-mix asphalt mixture; and in terms of low temperature performance and water stability, the former is equivalent to the latter.

Abstract: Railway track irregularity has significant impact on traffic safety. It can ensure high smooth of the track from predicting the deterioration of track irregularities accurately, and then fundamentally eliminate hidden dangers. In this paper, a multi-stage linear prediction method for track local irregularities based on time series is proposed. On the basis of the track irregularity management standard in our country, this paper has researched the changing regularity of irregularities in unit section and built the local irregularities deterioration model for each unit section to forecast the development of irregularities during a maintenance period. After comparing predicting data with actual data and analyzing the error, the accuracy of the model was verified.

Abstract: Based on the results of electron microscope observation, the formation mechanism of asphalt rubber can be explained as followed: both chemical and physical reaction take place when crumbed rubber and base bitumen are mixed together. Physical swelling of the crumbed rubber particles take place during the process, at the same time a layer of gel comes into being on the surface of the crumbed particles, through which the particles connect with each other and form a network structure. Because of the unique formation mechanism of asphalt rubber, the material provide some much better properties than other kinds of bitumen. The main points of choosing raw material and production technology of asphalt rubber is given out based on the results of a series of contrast tests such as different sizes of crumbed, different crumbed rubber content, different reaction time and different reaction temperatures. The good performance of asphalt rubber in the field of road engineering is proven based on the test results of asphalt rubber premix and road pavement.

Abstract: In the construction process of asphalt pavement, mixing is the process which brings most of carbon emission. There is huge potential advancement of energy conservation, emission reduction and consumption reduction in the construction of asphalt pavement. Research on the structure improvement of construction equipment, the optimizing of the construction technological process and the influence of mixture performance and parameters is necessary. It is feasible to conduct interdisciplinary research in the condition that construction quality is ensured. There needs excellent control technology on efficient paving, efficient compaction and appropriate equipment match and temperature segregation of mixture. By doing this, the purpose of energy conservation and emission reduction in the construction process of hot-mix asphalt mixture can be achieved.