Study On The Techniques Of Cavity Beneath Slab In The Treatment Of Cement Concrete Pavement By Modified Emulsified Asphalt&Cement Based Composites

In recent ten years, many heavy loading cement concrete pavement of expressway havebeen built in Shanxi province, such as Jingda, Xiafen, Daxin, Deda, which effectively ensurethe unimpeded coal transportation and promotes the development of the local economy.However,3~5years after the operation, the cement concrete pavements occur the damage insome degree, for example mud pumping, dislocation, corner fracture, broken slab, crushingand so on. The investigation and analysis indicate that many reasons lead to the early damageof the pavement, not only relates to the construction quality, maintenance management andoverload but also to the formation and development of cavity beneath slab.In the use of cement concrete pavement, warping deformation is caused by the change oftemperature and humidity, which results in the contact discontinuity between slab and basecourse. Under the function of repeated load, the accumulation of plastic deformation in basecourse materials will also leads to the cavity beneath slab. Furthermore, pump suction effectcan also result in the erosion which can leads to the cavity on the bottom of base course. Theformation and development of cavity beneath slab decreases the service life of pavement,increases the maintenance cost, and decreases the rideability. So, how to treat the cavitybeneath slab is the key technical problem for the road management department.Based on the deep survey of the current situation in the domestic&foreign research, andfield investigation of operation, maintenance and diseases of the cement concrete pavement,the study on the mechanism of treatment of the cavity beneath slab by emulsified asphaltcomposites is carried out; material composition design is determined by the laboratoryexperiment, and the application feasibility&scope are also determined in such technique;Through the theoretical analysis and evaluation of cavity beneath slab, the law of deflectionvariation of concrete plate is studied; The correction method of warping deformation bytemperature in the plate deflection and the cavity determination method and its operationprocess based on the deflection index are both put forward; The technique of treatment ofcavity beneath slab is discussed, evaluation method of the treatment effect is given and theeconomy benefits are also analyzed in the paper.