Expansion joint is an important part of bridge structure，under the effect of concrete shrinkage, temperature changes,live load, the settlement of bridge pier and creep,bridge span structure will produce deformation so that make the bridge beam produce the displacement.In order to apply this kind of displacement and maintain the vehicles driving smoothly on the bridge,which must be between the ends of the bridge deck and the beam end and the abutment back wall set up between the transverse expansion joints.Once the bridge expansion joint is damaged,Will lead to jump car safety, noise,leaking and shorten the service life of the bridge.And there is relationship in the process of quality control between the quality and construction of the bridge construction joint.
The types of bridge expansion joint
1.steel Plate type expansion joint
There are two forms of steel plate type expansion joint:One is the zinc iron u-shaped expansion joint,It is used for pavement,Low cost, convenient construction;Second is the lap plate expansion joints,it has a certain strength and can bear big wheel load.But the durability, driving, shock absorption is poor.
2.Packed type expansion joint
This kind of expansion joint expansion amount is small,about 0 to 25 mm,the materials used are felt and asphalt,this kind of expansion joint construction process is simple,low cost,more commonly found in small span bridge.The expansion joint filler will be squeezed out under the heat condition,and at the cold extrusion of packing can't recover.And because the water proofing property is damaged due to sand sundry occupy the gap,At the same time can cause steel corrosion board.Use fixed number of year is shorter.
3.Geotextile expansion joints
Geotextile expansion joints are zinc iron modified u-shaped expansion joint,with economy, the construction the advantages of simplicity and driving comfort,theoretically superior to other types of expansion joints.
4.Plate rubber expansion joint
Because of the rubber material of transgender and shock absorption,its waterproof performance and reduce noise performance is better.At the same time, due to its construction technology is simple, and can meet the needs of the general bridge expansion amount,so the plate rubber expansion joint are more widely applicable scope.
Construction process and method of bridge expansion joint
1、The bridge expansion joint construction preparation
In front of the bridge expansion joint construction，it is need for a series of preparations for construction.For the bridge deck,now in order to ensure the quality of construction control is simple and can achieve high,general requirements of expansion joint construction are in after the completion of the bridge deck black pavement continuous paving.In view of the expansion joints,before the construction must be to check the quality of expansion joint,production factory in strict accordance with the requirements of the methods for loading and unloading, placement and transport.for generating the bending and torsion of expansion joints cannot be used.In view of the bridge expansion joint construction with concrete,must choose high quality cement and aggregate.And through the indicators test qualified,under normal circumstances the strength of the concrete to a level higher than of the beam body.when it need can be mixed with a certain amount of admixture;According to installation location value under the condition of different temperatures may have different values,required to install location value must satisfy the highest temperature expansion joint with a minimum width and must be left to spare,the lowest temperature cannot exceed driving requires the largest gap.
2、Construction process and method of bridge expansion joint
In front of the bridge expansion joint construction related preparation work，The following is the bridge expansion joint construction。Generally speaking,bridge expansion joint construction is divided into four steps:Slot, installation, pouring and curing of concrete.