Research On The Effect Of Salt Frost And Chloride Erosion On The Performance Of Concrete Bridges

The rapid development of China's transportation industry has driven the construction of highways and railway bridges.A large number of bridges with reinforced concrete as raw materials have been put into operation.China has a vast territory and the service environment of bridges is also different.With the expansion of the application range of concrete bridges,more and more concrete bridges are affected by the cold environment,and the durability of reinforced concrete bridges is also increasingly prominent.Corrosive ions in the soil cause salt frost and chloride ions erosion to concrete bridges,which pose a threat to the safe use of concrete bridges.Therefore,it is necessary to carry out the research on the influence of salt frost and chloride ion erosion on the performance of concrete bridge in Zhangjiakou.The main work of the thesis includes the following aspects:(1)Site investigation: Make full use of the collected bridge data to conduct on-the-spot investigations of reinforced concrete bridges in the cold region(taking Zhangjiakou as an example),and objectively evaluate the service status of concrete bridges in the Zhangjiakou area.(2)Soil inspection: During the investigation,the soil of the service environment of the bridge was sampled.Determine the grade of soil salinization scientifically through inspection and analysis.(3)Mechanism analysis: According to the survey results,it is clear that chloride ion erosion and freeze-thaw cycles under salt environment are the main factors leading to the concrete bridges in Zhangjiakou area.Combined with the destruction of the bridge,the mechanism of chloride ion erosion and salt freezing is explained through the theoretical analysis system.(4)Experimental research: Conduct the experiment through the control of concrete mix with admixture and mineral admixtures of different types and dosage analysis of its impact on the performance of concrete.Finally,from the perspective of improving concrete resistance to chloride ion erosion and salt resistance,we can draw a reasonable dosage of admixture and mineral admixture.(5)From the aspects of design and construction,specific measures to enhance the performance of concrete bridges in cold regions of Zhangjiakou are proposed.The design not only includes the choice of environmental grade and bridge structure,but also presents the principles and methods of durability design from the aspects of bridge foundation design,bridge support design and bridge drainage design.In the construction area,it concretely expounds the concrete curing problems and the construction joints retention problems.