Research And Application Of Rapid Repairing Materials For Bridge Expansion Joints

In recent decades,China's highway industry has developed rapidly,along with the continuous growth of new highway mileage,the development of highway maintenance materials and technology has attracted more and more attention,and the maintenance of bridge expansion joints has always been a difficult problem to solve.The construction time of conventional cement concrete repair materials is longer,which results in the decrease of road traffic efficiency,and the service life of fast-hardening concrete and modified asphalt concrete is shorter after maintenance.In view of the causes of damage and service conditions of expansion joints at present,this paper puts forward a rapid repair material for expansion joints.By compounding polymer and high-quality aggregate in fast-hardening concrete,the excellent large deformation and cracking resistance of polymer materials are utilized to improve the impact deformation performance of concrete materials,and at the same time to improve the interfacial bonding performance of concrete,which can meet the requirements of rapid repair,at the same time,has the following advantages:Good function of expansion joint.The main research contents include the following aspects:Firstly,by investigating the types and status quo of expansion joints of some expressways and secondary highways in Gansu Province,the failure forms of expansion joints are summarized,and the causes of their diseases are analyzed.It is shown that the destruction of anchored concrete is the main form of bridge expansion joints in Gansu Province.Secondly,according to the construction requirements and open traffic time requirements,referring to the relevant literature at home and abroad,the index of rapid repair materials for bridge expansion joints is put forward,and the selection of repair materials and test methods is carried out according to this standard.Various factors affecting the properties of rapid repair materials for expansion joints are expounded in terms of cement,stabilizer,polymer and various additives.The composition and mix design of cementitious materials are determined.The setting time,dry shrinkage,crack resistance and strength of repair materials with different polymer content are studied.The results show that polymer modified cement mortar and other water are effective.Mud mortar has better dry shrinkage resistance than mortar,and the dry shrinkage resistance increases with the increase of polymer content.Compared with other cement mortars,the addition of polymer reduces the compression-fracture ratio of cement mortar,improves the flexibility and crack resistance of cement mortar,and decreases with the increase of polymer content.Thirdly,freeze-thaw test,dry-wet cycling test in chloride solution and electric flux test were used to analyze the influence of different polymer content on the durability of concrete,such as frost resistance and chloride ion corrosion resistance,through strength,mass loss and chloride ion diffusion rate.The results showed that the compressive strength and flexural strength loss of concrete were obvious with the addition of 4%polymer.Under the condition of Salt-Freeze coupling,the addition of chloride salt aggravates the degree of freeze-thaw damage.In terms of chloride ion resistance of polymer mortar,the bending strength,compressive strength and bonding strength of the specimens cycling in chloride solution all decreased,while the addition of 4%⁶%polymer could reduce the loss rate of precursor to the greatest extent,and with the increase of polymer content from 0%to 6%,the chloride ion diffusion coefficient decreased from 13.3*10^-8to 6.6*10^-8m²/s.Finally,based on a large number of test data and combined with practical construction cases,the economic and social benefits of rapid repair materials for expansion joints are analyzed,and the relevant conclusions in the paper are summarized.It is found that the direct economic benefits of using quick repair materials for bridge expansion joints are 383 yuan/m higher than that of traditional maintenance technology,but the maintenance efficiency of bridge expansion joints is improved and the vehicle is improved.In the long run,the service life of the bridge expansion joint repair system is 3-5 times longer than that of the traditional bridge expansion joint repair system,and the later maintenance cost is less.