Applied Mechanics and Materials Vols. 361-363

Abstract: Shrinkage of semi-rigid materials like cement treated base subjected to thermal coupled with moisture has raised crack in semi-rigid base, which causes reflective crack in the asphalt concrete top layer. The deformation characteristics of cement treated base subjected to thermal coupled with moisture is researched through the strain acquired by the vibrating wire string gauge installed in the cement treated base while construction. And it is found that transverse deformation is larger than longitudinal strain which may raise greater stress in longitudinal direction as the restriction is stronger.

Abstract: Establish the mechanical model of asphalt pavement low-temperature cracking, analysis the factors leading to cracking. The factors such as shrinkage coefficient of asphalt pavementtemperature stresspavement structure combination forms and temperature contribution affect the asphalt pavement on cracking behavior. Study the effect of aggregate gradation type on asphalt mixture temperature shrinkage coefficient, analyze shows that in case of the same skeleton type, the smaller the average particle size of aggregate is, the larger low-temperature shrinkage deformation of mixture is; increasing the amount of coarse aggregate can form the dense structure of skeletonreduce the shrinkage coefficient at low temperature and improve the low-temperature crack resistance ability of asphalt mixture.

Abstract: Through a comparative study of high-temperature asphalt mixture performance by three methods: the standard rutting test, uniaxial penetration test on cylindrical specimens, and slant shear test, this paper displays that the shear elastic modulus gained by both cylindrical uniaxial penetration test and slant shear test can reflect well the properties of shear deformation of asphalt mixture under high temperature. However, there are certain limitations in these test methods.

Abstract: The warm mix asphalt technology was introduced to breaks through the low reclaimed asphalt pavement (RAP) ratio in central plant hot recycled engineering. Firstly, performance tests for traditional hot mix asphalt and central plant warm recycled asphalt mixture with different RAP ratios (0%,40%,50%,70%,100%) were conducted. It was concluded that the performance of warm mix asphalt was as good as hot mix asphalt, and the RAP ratio could increase to 60% by central plant warm recycling technology. Then a practical central plant warm recycled engineering with RAP ratio 50% was analyzed. It was concluded that not only the performance of the recycled asphalt mixture met the standard requirements absolutely, but also the compaction quality of the recycled pavement was improved.

Abstract: In order to realize continuous detection of rail short wavelength irregularity and improve its detection precision, a new four-point method based on chord reference method is derived and presented. Then a simulation waveform consisting of 10 random sine waves has been used for scientific determination of the three separation distances. The new method’s automatic recovery program is developed by MATLAB. The restored waveforms are compared with the results from RMF-2.3E devices and thus the detection precision is achieved. Results show higher detection precision and reliability by over 87% relative percentage comparing to the traditional three-point method, which shows the great applicability and superiority of the new method.

Abstract: Analyze two problems why blending ratio of plant-mixed RAP generally cannot be more than 40% to 50%. Prove pre-heating and sieving of RAP is a key technology to solve the problems. Design a high blending ratio of RAP recycling plant. Through construction of high blending ratio of RAP Hot recycling plant and testing pavement proved that applied ratio of RAP in hot plant mixed recycled can be increased to more than 70%.

Abstract: In this paper, influences of New Generation Large Aircrafts (NGLA) on the runway rutting were analyzed and the importance of combining laboratory performance tests and suitable analytically-based methodology was emphasized. Based on the multilayered elastic theory, the vertical compression stress distributions under different airplanes including NGLA were studied. Then the dynamic creep test was conducted to obtain the visco-plastic characteristics of pavement including three mixture types. Furthermore, the rutting depth under different airplane was predicted by employing the Shells method and the dynamic creep test results. The results showed rutting depth would be more significant by loading cycles of NGLA, compared with that by ordinary airplane. Suggestions composed of both the structural and material considerations were proposed for runway pavement design.

Abstract: Because of the heating limitation of old pavement and the restriction of climate, the quality of hot in-place recycled pavement was different to control. The warm m,ix asphalt technology was introduced to improve the heterogeneity and compactness of the hot in-place recycled pavement and decrease its construction temperature. The compaction characteristics of warm in-place recycled asphalt mixture were analyzed and its molding temperature was determined through the Marshall test. The pavement performance of warm in-place recycled asphalt mixture was analyzed whose results indicated that the introduction of warm mix asphalt technology was able to improve the compactness, the high temperature stability and water stability of hot in-place recycled asphalt mixture and reduce the influence of environment over its construction quality. A warm in-place recycled engineering of Shian expressway was introduced to verify the feasibility of warm in-place recycling technology which demonstrated that the warm in-place recycling technology was able to improve the heterogeneity and compaction quality of the recycled pavement and weaken the environmental pollution.

Abstract: Combined with practical engineering, the second-class level measured data is got via stack preloading experiment on the soft and weak railway subgrade. By using the hyperbolic method and three points method to fit subsidence curve, the post-construction settlement S (t =∞) and the settlement at any time S(t) is evaluated, then a reasonable unloading time is inferred by the comparison between S (t =∞) and S(t=180). Studies have shown that hyperbolic method and three points method can predict the post-construction settlement accurately, the time unloading six months after the stack is completed is quite reasonable.

Abstract: Based on ABAQUS software, a 3-D finite element model which content the nonlinear contact problems and contact-earth subgrade-monilithic was given to analysis the mechanical behavior of the monolithic roadbed. Mechanics behavior and deflection of the monolithic roadbed, deflection and compressive stress of earth subgrade evaluated in detail with respect to varied structure layer combination and materials parameters. The results indicate that the increase roadbed thickness can significantly reduce the monolithic roadbeds tensile stress, which can reach 1.042MPa. With the increase of the friction coefficient, level of tensile stress σ_dy, monolithic deflection D_d , the compressive stress σ_sz and deflection on earth subgrade were slightly reduced.