Research On Characteristics Of Waterproof And Bonding Layer Of Asphalt Pavement On Concrete Bridge Deck

In recent years,the highway network of China has been continuously improved,the construction of the expressway gradually shifted to the hilly area,so the proportion of bridges,especially cement concrete bridge,has increased further.The attention on bridge deck pavement which is an important part of bridge is also much higher than before.Due to the lack of systematic and perfect guidance on the design and construction process,many diseases of the bridge deck pavement system appeared earlier,especially when water penetrates into the waterproof and bonding layer through road defects,road edges and other large voids,leading to many problems such as water leakage,looseness,pits,slops,and convection,it seriously affected the quality and service life of the deck.Therefore,this paper addresses the waterproof and bonding layer that may cause damage to the bridge deck pavement,the focus is on the void structure and interlayer horizontal water permeability of waterproof layer,the target is to choose the layer with excellent overall performance by combining with the road mechanical properties.This paper first analyzed the causes of the bridge deck pavement disease,summarized the types and performance requirements of waterproof and bonding layers at home and abroad,designed and formed the several waterproof and bonding layer composite board specimens combined with the actual project.By using CT scanning technology,we obtained grayscale images of layers.Computer software was used to get and analyze different parameters such as air void ratio,air void equivalent diameter,air void quantity and area by analyzing these images,the inter-layer void structure was visually demonstrated by using three-dimensional reconstruction of inter-layer voids.Based on this,a new type of interfacial infiltration meter was used to test and analyze the water seepage characteristics of various waterproof layers under different conditions,such as water pressure,interface type,compaction process,etc;interlayer pull-out test and shear test was used to analyze the influence of the type of waterproof layer and interface type on the mechanical properties between layers.In addition,the influence of water immersion and freeze-thaw on the mechanical strength was also been contrasted.The CT analysis showed that,the change trends of void ratios among different waterproof layers are similar,but the peaks and ranges are different;the void equivalent diameters,the void quantities and the void areas of different waterproof layers have their own characteristics;it can be seen directly from the three-dimensional model of voids that the void structure and connectivity of different waterproof layers are different.The water seepage test using the developed interfacial water seepage meter showed that,the sequence from good to bad of impermeability performance of several types of waterproof layer is: emulsified asphalt waterproof layer> thin slurry sealing layer > AC-5 asphalt sands> synchronous gravel,under the same conditions,the higher water pressure and the rougher interface can reduce the permeability resistance between the layers.The shear test and pull-out test show that,the mechanical properties of different waterproof layers are different,AC-5 asphalt sands have higher mechanical strength;water immersion and freeze-thaw reduce the interlaminar mechanical strength;we can increase the drawing and shear strength of the synchronous gravel by improving the amount of bitumen or reducing the amount of gravel,shear strength is positively related to the roughness of the interface.