The Testing Research On The Contribution Factor Of Rushed Stone Seal Coat Performance

The technique of crushed stone seal coat is applied to the pavement engineering for a long time,which is a successful overlay technique.Such kind of technique is generally used in the city road,also in the heavy traffic road in some countris, and is applied to preventive maintenance and rehabilitation of pavement fuction by USA.Which is applicable to the reconstruction of low-level road and overlay to the high-level,also to the overlay of the new pavement and maintenance of the old one. However the failure is not rare.The three main damage is :spalling of crushed stone,bleeding and bulling.Carrying the test of destoning rate, found that, different materials of particle-size crushed stone in the same other conditions have similar results,the materials which of same particle-size but of different aspht,A-70 is at the maximal destoning rate,SBS modified asphalt inferior,Sasobit modified asphalt least,but which is similar to the SBS modified asphalt.Hydrodynamic pressure impact the destoning rate of crushed stone seal significantly,which impact the destoning rate in low-grand when speed belows 60km/h, high-grand above 90km/h,much more high-grand above 120km/h.Using Bisar program to caculate the shear stress of the bottom and the 45-D0548 SST to put up in-door experiments,the paper takes the maximum shear strengthτmax as index,the results show:on condition of completely continuous and none-horizontal stress,the maximum shear stress between original pavement and seal is less then that between original pavement and roadbed,on state of completely sliding,the maximum shear stress between lower layer of seal has increase by 72.8%,and that whenα=0.99 construction NO.1 has more of 49.3 % shear stress than construction NO.2, which illuminate that it is much more important to ensure the continuity between layers than to control the maximum shear stress.In all impacting factors,temperature changes and differ of underlying layer construction are the most significant ones,adopting modified asphalt and asphalt dosage under adoption of 6.30mm~9.5mm particle-size crushed stone,increasing texture depth of underlying layer(TD),can increasing maximum shear strength significantly.