Study On The Influence Of Concrete Cracks Upon The Chloride Ion Erosion

Abstract:The chloride ion corrosion is the main factor of influencing durability of concrete, while the appearance of concrete crack, not only aggravated the chloride ions invasion process, but also damaged the integrity of the whole structure. It’s of great theoretical and practical value on engineering to study the effect of cracks on the chloride ion erosion, and then to predict the cracking of concrete durability life and take corresponding measures to improve its service life.Relying on the National Natural Science Fundation (No:51278495): research about the influences of concrete cracking condition on its internal reinforcement corrosion, The thesis takes reinforced concrete slab under continuous load crack condition as research object, focuses on the influences of permeability of concrete structure and rebar corrosion rate caused by chloride ion erosion. Its key researches are as follows:(1)The thesis has analyzed the transmission mechanism of chloride ion in the cracking of concrete and the influence principle of reinforcement corrosion caused by the chloride ion. In allusion to the shortages of the study on influence durability of reinforced concrete structures under chloride ion erosion, the thesis carries out a chlorine salt immersion test under continuous load of reinforced concrete slab cracking conditions.(2) This paper gives a detailed analysis on chlorine ion concentration of each section of the test specimens and analyzed the influence of water cement ratio, crack width and the erosion of time change the influence of permeability of concrete on Permeability of concrete, gets the diffusion regularity of chloride ion in cracking in concrete, establishes a chloride ion diffusion model which takes into account crack, water cement ratio, time and some other factors. The diffusion model in this paper was proved to have great practicability and applicability through engineering a example.(3) Through the analysis of the cracking concrete transverse crack area steel corrosion current density over time, the paper gets the influence law of reinforcement corrosion that the water to cement ratio, cover thickness and crack width on reinforcement corrosion. The steel corrosion rate test model is established and verified. Relevant conclusions in this paper can provide reference for engineering.