Research On The Thin Overlay Maintenance Time And Interlayer Technology On Old Asphalt Pavement

In recent years, with the gradual promotion of preventive maintenance technology, Paving thin overlay technology on old asphalt pavement is also widely used. Paving thin overlay technology on old asphalt pavement as a kind of beforehand, active preventive maintenance technology, how to determine the optimal maintenance time is particularly important; At the same time, in the process of the practical application of this technology, due to the interlayer performance instability of thin overlay and the old asphalt road lead to disease. Interlayer performance stability is a key factor of whether or not to play its thin overlay preventive maintenance functions. Therefore, research on the optimal maintenance time of the thin overlay and the performance between the layers has important theoretical significance and practical value.First of all,on the basis of the analysis of the preventive maintenance optimal time commonly used at home and abroad, apply life cycle cost analysis,through effect(benefit)-cost ratio, it is determined that the optimal timing of maintenance.Then, through the study on the performance of bonding layer material of the thin overlay structure and the interlayer bonding strength theory, by using BISAR3.0 software to analysize the interlaminar mechanical response under traffic loads, get the maximum shear stress between the layers appears in the center of the single wheel under the front of the area, and the maximum tensile stress appears in the center of the single wheel at the back of the area. Horizontal force coefficient overlay thicknessn、surface layer thickness、temperature, etc. have a greater iMPact on the maximum shear stress and the maximum tensile stress between the layers, and puts forward the interlayer bonding technology index of the thin overlay structure.Finally, we found the variation between thin overlays shear strength along with the content of bonding materials by the implementation of direct shear tests on two kinds of Thin Overlay materials and three kinds of bonding materials. From the direct shear tests, we obtained the optimal asphalt content of these bonding materials corresponding to two kinds of thin overlay materials. At the same time, we ultimately determined that SBS modified asphalt has good adhesive properties,70-A asphalt followed, emulsified asphalt modified slightly worse. However, the shear strength of these bonding materials can satisfy the requirements of shear strength index we proposed. From the tests which considering different temperature and soaking conditions on the performance of the adhesive layer, we can conclude that both of them have effect on the shear strength of the adhesive layer. Among these three kinds of bonding materials, SBS modified asphalt are greatly influenced by the two factors,70-A asphalt followed, modified asphalt emulsion affected is relatively weak. Through the pullout test that the adhesive layer under the optimal asphalt content, we conclude the variation of pullout strength between layers and the pullout strength of test satisfy the requirements of also strength index we proposed.