Study On Asphalt Overlay On Highway Cement Concrete Pavement Structure

Based on practical engineerings of Fujian Province, load transfer characteristics and evaluation technique of JPCP pavement, the working mechanism of geotechnical grille types and stress absorbing types technology, the temperature field properties and influence effect of asphalt overlay structure,and the design method of asphalt overlay pavement were studied by field test, laboratory tests, numerical simulation and theoretical analysis, specific as follows:Base on the ABAQUS numerical simulation, theoretical analysis and field test, found that the deflection difference of load transfer was closely related to Specific road conditions, season, test methods (like axle load, uphill and downhill, the location of testing), and traditional test evaluation might be misjudgment. The optimization measures of deflection difference testing were suggested through theoretical research.The main vehicle axle load was suggested to assessment the deflection and load transfer of heavy traffic road.The working mechanism and the influence of characteristics of geotechnical grille types cracking controlling technology were studied through fracture mechanics theory and finite element method, the study found that the setting layer, metal mesh equivalent thickness and the joint deflection difference of old pavement is significant influence. The referenced technical indexes (like the tensile strength, overlap width, metal mesh’s spacing) and suggested values of lass fiber geogrid or metal mesh were suggested through theoretical study.The working mechanism of stress-absorbing types cracking controlling technology was studied through finite element method and stress intensity factor, the study found that stress-absorbing layer is a mixture viscoelastic properties and deformation recovery to dissipate the old board seams stress concentrate enegry; aggregate nominal maximum particle size, the asphalt material type, the amount of asphalt have significant influence on the anti-crack effect of stress-absorbing. The energy consumpation and kinetic parameters (like storage modulus, loss modulus, phase angle) were suggested as the evaluation indexes to evaluation the pavement performance of stress absorbing layer.Through stress-absorbing layer’s asphalt material laboratory test and found that, the softening point, penetration, viscosity and elastic recovery indicators of stress-absorbing layer’s asphalt material were high currently, but the low-temperature ductility index is lower.For of Fujian high temperature and stress-absorbing layer’s asphalt material properties, the needle penetration index of TFOT 5,15,25 and 30℃, the viscosity 170℃, the elastic recovery of 5℃ and 10℃ were suggesed being focus on. The dynamic loss factor tanδ and dynamic viscosity index VTS*, The complex modulus temperature index CMTS, G*/δ temperature index were suggested as the elastic recovery Index and temperature sensitivity Indexes of stress absorbing layer’s asphalt by DSR test because of their well dipartite degree and effectiveness.The temperature field properties and influence effect of asphalt overlay structure was studied by field test and numerical simulation, the study found that solar radiation, wind speed, road surface radiation absorption rate and thickness is the main factors of the JPCP+AC steucture’s temperature field. Study found that, compared with ordinary asphalt pavement, the temperature gradient of asphalt overlay is bigger, and the temperature gradient of old JPCP pavement had sensitive thickness of overlay.At last, the design method of asphalt overlayer on JPCP pavement base on cracking tolerance and antireflection cracking effect economic cost ratio was established by considering the technical level of antireflection cracking and the actual situation of reconstruction project. And the evaluation factor and calculating method base on the equivalent extended distance of asphalt overlayer reflective cracking matching to this design method were established, through fracture mechanics theory, Miner’s law and construction reliability concept.