| Crack is one of the common diseases of asphalt pavement. Surface filing is the mainly repairing technology of asphalt pavement in China, which has poor durability and high failure rate. Therefore, studying on repairing technology of cracks in asphalt pavement is important to improve the efficiency of pavement maintenance, to keep the use of the pavement performance, to extend the pavement service life.Based on one southern expressway, combined with the feature of the asphalt pavement cracks, a new independent chemical grouting material is used to repair cracks in asphalt pavement. The compatibility between grouting material and asphalt mixture is evaluated by comparing the mechanical properties of asphalt mixture repared and after, and put forward an efficient asphalt pavement crack repair construction technology. The main contents are as follows:(1) The crack distribution, crack width, crack depth and crack core sample extraction from asphalt pavement of the southern expressway’s typical section is investigated. The results show that, the average width of the cracks is4-6mm, the average crack depth is more than60mm. The main types of cracks include the transverse cracks formed by temperature changes, the longitudinal cracks causing by fatigue load or subgrde settlement.(2) Mixing epoxy acrylate with polyurethane prepolymer to modify grouting materials, and prepared EA/PU IPN interpenetrating polymer network structure modified grouting materials. The effects of different dosage polyurethane prepolymer on the performances of EA/PU IPN grouting material viscosity, mechanical performance, volume stability, ageing-resistant performance is investigated. The results show that:the comprehensive performance of EA/PU IPN grouting material is best when polyurethane prepolymer content is30%, its viscosity is188.2mPa s, the tensile strength is35.82MPa, the shrinkage rate is2%, lOd aging tensile strength is9.1%less compared to non-modified.(3) The mechanical properties of asphalt mixture and repaired composite structure system under different temperature are compared through three-point bending experiment, splitting experiment, oblique cutting experiment, the mechanical compatibility of repair materials and asphalt mixture is evaluated. The results show that:the repaired composite structures has well temperature anti-cracking performances. Flexural-tensile strength at0℃reached93%of the original specimens. The flexural-tensile strain of repaired composite structures are meet the specification for the minimum tensile strain of low temperature crack resistance. Fracture energy of repair composite structure is closed to original specimens at low temperature (0℃～10℃), the highest can up to103%. The stress-strain curve show that deformation performance of repaired composite structure are better at low temperature.To evaluate low temperature crack resistance, bending tensile test is more comprehensive and accurate than splitting tensile test. The shear strength of composite structure at different temperature were higher than the original specimen, which amounted to220%when the temperature is50℃. The ability of the resistance load and deformation capacity is better under higher temperature.(4) Three mending methods of nondestructive crack repair, the slotted crack repair, and drilling pressure grouting were proposed based on the width and damaged condition of the cracks, and the strong penetration of the repair materials. And put forward a set of efficient grouting construction technology and procedure such as the slotted, clear joints, drilling, grouting nozzle installation, the pouring material preparation, seam sealing, pressure grouting and keeping in good health. |
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