Highway Engineering Key Laboratory of Sichuan Province

Chengdu, China

Highway Engineering Key Laboratory of Sichuan Province

Chengdu, China
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Xin C.,University of South Florida | Xin C.,Southwest Jiaotong University | Lu Q.,University of South Florida | Ai C.,Southwest Jiaotong University | And 5 more authors.
Construction and Building Materials | Year: 2017

Surfacing steel decks is one of the key technical issues facing engineers during construction of long-span steel bridges. The objective of this study was to improve the high-temperature performance of gussasphalt (GA), one of the preferred surfacing materials for steel deck bridges around the world, by optimizing its binder formula. Three types of asphalt binders (i.e., styrene-butadienestyrene [SBS] modified asphalt, Trinidad lake asphalt [TLA], and NES-1 rock asphalt) were selected as basic constituents to achieve an optimized asphalt binder, which is known as hard modified asphalt. Abiding by the principles of uniform experimental design, a series of laboratory tests for penetration, ductility, ring-and-ball (R&B) softening point, and viscosity were conducted to assess and optimize the binder performance. With the laboratory testing results, quadratic polynomial stepwise regression analysis was performed to obtain four nonlinear multiple regression models for the relationships between performance and compositions of the hard modified asphalt. It is shown that NES-1 rock asphalt has more significant influence than Trinidad lake asphalt on improving the high-temperature performance of the hard modified asphalt. In order to ensure mixing workability and low-temperature performance of gussasphalt, the contents of NES-1 rock asphalt and Trinidad lake asphalt should not exceed 5% and 30%, respectively. The optimum formula of hard modified asphalt for gussasphalt is 75% SBS modified asphalt, 20% Trinidad lake asphalt, and 5% NES-1 rock asphalt. The performance of the optimized hard modified asphalt was validated by laboratory tests. © 2017 Elsevier Ltd

Ai C.-F.,Southwest Jiaotong University | Ai C.-F.,Highway Engineering Key Laboratory of Sichuan Province | Huang D.-Q.,Highway Engineering Key Laboratory of Sichuan Province | Huang D.-Q.,China Railway Siyuan Survey and Design Group Co. | And 6 more authors.
Huanan Ligong Daxue Xuebao/Journal of South China University of Technology (Natural Science) | Year: 2017

In order to reveal the effect of seasonal temperature variation in the areas with large temperature difference on the performance of asphalt pavement, this paper takes into consideration the time-temperature viscoelasticity of asphalt concrete, and performs numerical simulations to analyze the dynamic behavior and performance under moving vehicle load and seasonal temperature variation for two kinds of typical asphalt pavement structures. One is the structure with a semi-rigid base layer containing cement-stabilized macadam (structure S1) and the other with a flexible base layer containing graded aggregate materials (structure S2). The results show that (1) with the increase of axle load, the decrease of dynamic load frequency, the change of horizontal thrust direction from the opposite to the same direction of the moving vehicle, or with the deterioration of interlayer conditions, the stress at the bottom of the asphalt layer generally increases, while the fatigue life gradually decreases; (2) the variation of pavement temperature distribution significantly influences the tensile stress of each structural layer in summer but slightly influences the stress in winter; (3) at the bottom of the surface layer, the tensile stress in summer or at high temperature is less than that in winter or at low temperature, while the base layer shows an opposite trend in this regard; and (4) although the fatigue lifetime of the asphalt layer of structure S1 under various age and temperature conditions is longer than that of structure S2, it has a deficiency of drastic fluctuation, while S2 has a relative stable fatigue behavior and a superior environmental adaptability. © 2017, Editorial Department, Journal of South China University of Technology. All right reserved.

Yang E.,Southwest Jiaotong University | Yang E.,Highway Engineering Key Laboratory of Sichuan Province | Zhang A.,Southwest Jiaotong University | Zhang A.,Highway Engineering Key Laboratory of Sichuan Province | And 4 more authors.
Xinan Jiaotong Daxue Xuebao/Journal of Southwest Jiaotong University | Year: 2017

Automatic detection method for pavement cracking based on 3D image technology has been a hot topic. In order to improve the accuracy and reliability of the cracking detection, a new method based on the 3D shadow modeling was proposed, which utilizes that the height of the fracture zone is lower than the surrounding area, and the shadow model was used to identify the cracking by the virtual light projection and then, the linear shape analysis method was used to discriminate cracks detection. Furthermore, both the connected-component analysis method and linear shape analysis method were adopted to remove the image noises. The results show that the automatic detection method can achieve 92.93% of accuracy in pavement cracking detection. © 2017, Editorial Department of Journal of Southwest Jiaotong University. All right reserved.

Ai C.,Southwest Jiaotong University | Ai C.,Highway Engineering Key Laboratory of Sichuan Province | Yang T.,Southwest Jiaotong University | Yang T.,Highway Engineering Key Laboratory of Sichuan Province | And 5 more authors.
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2014

Composite beam samples were made bonding with modified asphalt mixture and cement concrete by special asphalt binder of seamless expansion joint, and the bonding performances were studied by direct tensile tests.The influence rules and failed states under different temperatures and conditions of interface bonding were analyzed, and the bonding failure causes were explained. The results show that (1)temperature has great effects on bonding performance. bonding strength decreases with temperature rising, but the decreasing rules are different in different temperature range, when temperature higher, the decreasing speed slower; (2)rough interaction can improve bonding performance, but the improving effects are different under different temperature, low temperature “prominent” and high temperature “indistinctive”; (3)the characteristics of bonding failure are different under different temperature, “brittle rupture ” under low temperature, “divulsion” under normal temperature, and “agglutinate rupture” under high temperature. ©, 2014, Wuhan University of Technology. All right reserved.

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