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Li Z.-Z.,Changan University | Li Z.-Z.,Petrochina | Chen S.-F.,Changan University | Liao W.-D.,Management Office of Hanshi Freeway | Chen H.-X.,Changan University
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2012

In order to evaluate the low temperature anti-cracking performance of mixture with compound modified asphalt at stress absorbing layers, test fixture and specimens were designed, test parameters were determined and disk-shaped tension experiment was carried out, and then the low temperature anti-cracking performance was evaluated by tensile stiffness, tensile failure strength and fracture energy. Furthermore, the influence of aggregate gradation, test temperature, asphalt binder and asphalt aggregate ratio on low temperature anti-cracking performance was analyzed. The results indicate that the fracture energy is the comprehensive index to evaluate low temperature anti-cracking performance, aggregate gradation sensitively affects anti-cracking performance, the mixture with gradation close to median limit is not the best and the rational test temperature to evaluate low temperature anti-cracking performance is 0°C; the low performance of common SBS modified asphalt can not meet the demand of stress absorbing layers under low temperature.

Li Z.-Z.,Changan University | Li Z.-Z.,Petrochina | Wang B.-Y.,Management Office of Hanshi Freeway | Chen S.-F.,Changan University
Chang'an Daxue Xuebao (Ziran Kexue Ban)/Journal of Chang'an University (Natural Science Edition) | Year: 2012

There is a guiding significance to study the stress states of stress absorbing layer of modified asphalt mix in composite pavement, especially for the material composition design. This paper established 3D finite element model based on the stress absorbing layer in composite pavement by finite element numerical analysis method, and analyzed the influence of axle load and the modulus of stress absorbing layer on the loading stress of stress absorbing layer. The results indicate that stress absorbing layer are in extremely detrimental stress state and there is stress concentration on its bottom beside junctures of rigid base, the percentage of stress growth in its bottom is more than 60%, and the lower the modulus of the stress absorbing layer, the more obvious the stress concentration is. In addition, the load stress changes as third-order polynomial function with its thickness. Especially, the loading stress in stress absorbing layers grows linearly as axle load rising, and axle load has the most remarkable impact on the stress of its bottom.

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