Research On The Void Prediction Of Cement Concrete Overly On Old Cement Pavement After Rubblization

MHB rubblization is a technology used to make old cement concrete pavement recycled as a part of new pavement in road reconstruction. This technology can conserve resources and reduce project cost. Generally, old cement concrete pavement could be used as base course after being rubbilized, and the overlay over the road base can be build with asphalt concrete or cement concrete. Cement concrete pavement has great advantages in our country. However, the erosion and cavity of the plain concrete pavement is common serious. This dissertation study the cement concrete overlay on rubblized old cement concrete pavement.Combined with the condensation process of cement concrete first, the dissertation analyzed the destroying process interface between the surface and road base from the angle of fracture mechanics. The new mechanism of the rubblization layer material being scoured based on three basic destroyed modes were provided; and the erosion performance of it had been analyzed. Also the erosion coefficient of the rubblization layer material was put forward.For further understanding of the scouring principle of rubblization layers, the dynamic load is used, and based on the theories of porous media, finite elements software ABAQUS was used to simulate concrete pavement under the coupled vehicle-water loading action. Calculation results indicated that pore water pressure was variable beneath slab of concrete pavement under the dynamic load action and there was a reversion between positive and negative pore pressure. The influences of materials on the pore water pressure were discussed. With test roads, the dissertation comparatively analyzes the pore water pressure on the top of different pavement structures under the dynamic load action, and the pavement structure with good anti-erosion performance was designed. Finally,55KPa was recommended as the dynamic water pressure of materials of rubblized layer in the laboratory scour tests.The shape and height of void was analyzed. According to rainfall and the anti-erosion performance of the base course materials, the relationship between the times of load function and the lost of materials caused by erosion was analyzed quantificationally. Reduction formula for scouring times of axle load and the correction factor for precipitation days within the life expectancy were provided. Then the prediction models of voids beneath slab corner and along longitudinal joint edge were established.By introducing the precipitation weather correction coefficient, the cavity predicion model is corrected. Taking into account the analysis above, the cavity precipitation method is firstly and systemly proposed. At last, the new measures prevent pavement structure from scoured such as setting isolating course between layers is given.