Baoshu-highway Project Profile  
Baoshu Highway which starts from north Baotou City shaerqin and end with South Ordos City guannianfang is an important western development project in western connection. Its total length is 37km and is a two-way four-lane highway. Yellow River Bridge is located in medium dry areas of neimenggu grassland. It is Hot and dry in summer, strong ultraviolet radiation, and is dry and cold in winter. So great temperature difference between day and night, Baoshu highway cumulative yield axis of design life is 1.58 × 107 times, Vehicles 1s heavy to transport coal mostly. The original design shows that Yellow River Bridge pavement uses C50 concrete +9 cm asphalt concrete pavement. and adhesive layer is Modified emulsified asphalt, above adhesive layer is waterproof layer. 

Program comparison of Synchronous Chip Seal and Modified emulsified asphalt waterproofing adhesive layer.
To do a good job of the Yellow River Bridge deck waterproofing adhesive laye and ensure the quality of bridge pavement, Management Office and The Technical Advisory Group studied domestic and international program of bridge deck waterproofing adhesive layer and compared the performance of various programs[1, 2, 3], Performance comparison of Synchronous Chip Seal and Modified emulsified asphalt waterproofing adhesive layer is shown in Table 1.  


The locations of Yellow River Bridge, heat duration time so longer in summer, for example highest temperature is up to 40 ˚Cabove. So Yellow River bridge deck pavement temperature will reach 60-70 ˚C. And temperatures are so low in winter. Temperature difference is so bigger between the all seasons, so a good waterproof adhesive layer is needed. After the viscous bitumen emulsion, pavement performance is reduced. Therefore, the performance of SBS modified asphalt pavement is better than SBS modified asphalt emulsion, and the performance of SBS modified asphalt Synchronous chip seal is better than SBS modified asphalt pavement.  

Raw material selection
Asphalt Binder. Bridge structure deformation is needed to be in elastic-plastic condition of waterproof adhesive layer. But traditional asphalt is easy to flow in hot temperature and easy to crack in low temperature. And low strength, poor ductility, severely restricted the effect of waterproof bonding layer, It is the performance comparison for SBS modified bitumen and SBS modified bitumen emulsion evaporation residue in table 2. It can be seen from Table 2: (1) SBS modified bitumen viscosity is high and elastic recovery is good. It can be well adapt to long-span bridges deflection; (2) SBS modified bitumen is good of low-temperature elastic, which enhanced the low-temperature resistance crack performance of asphalt concrete pavement; (3) There is a good adhesion between the SBS modified asphalt and cement concrete in order to enhance the bonding effect between the asphalt concrete pavements and cement concrete pavement. 


Single particle size gravel. Baoshu highway surface aggregate is mainly from the Daqingshan where is rich of gravel. most is granite gneiss. And gravel of bridge deck waterproofing adhesive layer used 12-14mm single size gravel of Baotou maoyuan gravel plant. Technical indicators are shown in Table 3.

Construction Technologies 
Configuration of construction machinery. Synchronization gravel seal construction machinery configuration is shown in Table 4. 



Cement concrete bridge deck treatment. Before the construction of Synchronization gravel seal, it is needed to process deck, and cut concrete laitance. The methods of deck treatment were more. And thr blast process clean the deck surface have many characteristic, such as evenly, and surface roughness without destroying the original bridge construction;. It exposes a considerable proportion of aggregate concrete in Cement concrete pavement surface. The construction depth of cement concrete pavement surface is 2-3mm. The process improve the layer bonding area and enhances the shear strength. During the construction of synchronization gravel seal of the bridge , forest extinguishers were used to swept along dust, debris, ensuring no water, loose, weak interlayer and so on.  

Spreading gravel seal. Synchronization gravel seal machine requires to automatically adjust the amount of asphalt，and to control the amount of gravel spreading. At the same time, gravel is required to spread the asphalt layer after spreading asphalt within 1-3 seconds. Synchronization gravel seal car moves to appropriate speeds, which ensure the matching of spreading of asphalt and stone. Spreading less than the local area should be spreading artificial complement, generally do not leak asphalt, does not overlap gravel, Take into account the lower temperature of construction site, used 0.2% SBS modified bitumen to cover wraps gravel, in order to enhance the adhesion of asphalt and gravel, The material temperature is180 ˚C,transport to the paving site after covered with tarp.

Construction Process. Material transport vehicles need to pass 166 times, to and from 332 times. If the Synchronization gravel seal sprinkled all pieces, then paved middle surface, transport materials vehicles transported material is 50t once. Heavy material transport vehicles roll repeatedly. Aggregate is crushed and be taken away easily, and then stick asphalt to produced the phenomenon of sticky wheels, creating a vicious cycle, in order to avoiding such phenomena, the sprinkled of Synchronization gravel seal use of subprogram construction method, example first sprinkled 1km, then to paving asphalt mixtures of the middle surface layer when Synchronization gravel seal is formed fully, after 1-2h; then sprinkled synchronization gravel seal for 1km, to pave the middle surface layer, loop. This method greatly reduces the phenomenon of sticky wheels and controls the quality of synchronization gravel seal very well. it Is the effective way to solve the sticky wheels. On-site construction equipment and gravel spraying results are shown in Figures 1 and 2.



Roll and shape. After spreading synchronization gravel, 16t rubber tire roller is to be used to compact 1 times immediately with a rolling speed in 2 ~ 3 km / h, not watering , u-turning, braking during the roller rolling. You can open traffic after1-2h after during rolling is completed. However, the speed should be limited to not more than 30km / h to prevent the wheels taking away the aggregate.

Constructing and Quality Control
(1) Strictly control the quality specifications of SBS modified asphalt is needed and The temperature of the SBS modified bitumen in Synchronization gravel seal machine is control ed between 170 and 180 ˚C. (2) Asphalt distributors must be heated, insulation, precision measurement devices, spraying out of the asphalt into a uniform mist, not leak spill, into banded, and shall not have accumulated. The amount of modified asphalt is 1.8-2.0kg/m2 ,when necessary, can be used to detect the amount of asphalt spray. The method is to pre-measured asphalt laying the amount on brown paper. (3) To prevent sticky simultaneous gravel seal material, transport vehicles should be eradicated synchronization gravel seal of bridge expansion joints timely (Expansion joints filling material is the sand, when the material transport vehicles through of the sealing layer, gravel and sealing layer are easy to sticking away together, and then stick away sealing layer elsewhere. This can result in a vicious cycle.) If the material transports vehicles sticky debris at wheels, should be to clean up tires before traveling onto the synchronous gravel sea.  

Construction effects testing
Pull-paving machine is used to detect asphalt bond effect of simultaneous gravel seal after paving concrete pavement. Test results are shown in table 5.  

Conclusions
Waterproof adhesive layer has a direct impact on the bridge deck asphalt concrete pavement performance. Synchronization gravel seal waterproof effect is good; adhesion is strong; shear strength is high. Construction is easy to be controlled. It is the flexible waterproof adhesive layer that a single-size gravel and asphalt binder bonded with each other to form an organic whole. Yellow River Bridge uses Synchronous chip seal to enhance the adhesive quality of asphalt concrete pavement and cement the concrete pavement. It can reduce the early disease of bridge pavement effectively and extend the service life. The method of sub-throwing Synchronous chip seal and removal of Synchronous chip seal at the expansion joints timely, is the effective solution to solve transport vehicles sticky wheel phenomenon. The study is of great value in terms of real project application.