Experimental Research On Anti Reflection Cracking Structure Of Ultra-thin Asphalt Overlayer On Cement Concrete Pavement

Adding an asphalt overlay on the old cement concrete pavement is a pavement maintenance and repair plan.Under the repeated action of the temperature and humidity cycle of the external environment and the vehicle traffic load,the cracks and joints on the old cement pavement will gradually expand and pass.Even through the asphalt overlay structure,cracks and other diseases appear in the pavement structure.Aiming at the asphalt ultra-thin bonding anti-reflective crack overlay structure system on the cement pavement in the active + passive combined defense mode,the cause and propagation law of reflective cracks in the asphalt overlay structure are simulated by finite element simulation.In the test section of the overlay structure system In the physical engineering,the fiber grating sensor is used to monitor the strain response of the cover structure under the driving load in real time,and the rebound modulus is tested by the portable drop weight deflectometer(LFWD),in order to verify the simulation results and the cover structure system The effect and design parameters provide technical basis.First,according to the basic theory of fracture mechanics and thermodynamics,the relationship between the propagation of reflective cracks and the stress intensity factor of the crack tip is discussed and analyzed.Based on the principle of preventing the occurrence of reflective cracks and delaying the propagation,a cement concrete pavement asphalt ultra-thin bonding anti-reflective overlay structure is proposed.system.The ABAQUS software was used to establish a three-dimensional finite element model to simulate the effect of changes in the physical parameters of the material,vehicle axle load,and grouting size on the stress intensity factor at the crack tip under the effects of temperature and vehicle load on the surface structure system.Relying on the test section of Sungang West Road in Futian District,Shenzhen,the cement pavement asphalt ultra-thin bonding anti-reflective overlay structure was implemented on the spot,and the encapsulated and protected fiber grating sensor was used to carry out field experiments to study and summarize the cement pavement asphalt ultra-thin bonding resistance.The strain response law of the reflector surface structure under different working conditions.The study found that the fiber grating strain sensor and temperature sensor protected by polymer encapsulation and metal tube encapsulation can adapt to the extensive construction work of road engineering.Increasing the driving speed and reducing the axle load of the vehicle are all conducive to improving the structural life of the cement pavement asphalt ultra-thin bonded anti-reflection cover.The local bottom grouting at the joints of the old cement pavement plays an important role in controlling and delaying the upward transmission of reflective cracks and extending the service life of the pavement.The expansion probability of open cracks increases with the increase of the thickness of the gravel seal and the vehicle axle load,but decreases with the increase of the modulus and thickness of the asphalt ultra-thin cover layer.When only the driving load and the vehicle load are coupled with the temperature stress,the probability of shear crack propagation increases with the increase in the thickness of the gravel seal and the vehicle axle load,and with the modulus and thickness of the asphalt ultra-thin overlay The increase and decrease.But when only subjected to temperature stress,the above factors basically have no effect on shear-type cracks.