The Influence Of Freeze-thaw Cycles And Chloride Ion Erosion On Concrete Damage Mechanism

As is known to all，the marine structure damage is extremely serious in the north coldarea，and the two major influencing factors are the freezing and thawing cycle and thechlorine ion erosion. Freeze-thaw cycles and chloride ion erosion of mutual promotion andprogression result the ocean structures often useful life of less than the required earlydestruction. Therefore，marine concrete structures in the freeze-thaw environment safety anddurability issues must be resolved，and study of the concrete damage mechanism subjected tofreeze-thaw cycles and chloride ion erosion has theoretical research value and practicalengineering significance.In this paper，four kinds of freezing and thawing medium (fresh water，0.5，1.0and2.0times the artificial seawater) are adopted，carrying out a concrete freeze-thaw cycle testresearch in four medium and reached the change rule of the appearance changes, mass lossand relative dynamic modulus of elasticity and the cube compressive strength subject tofreezing and thawing of concrete specimen. In addition，cube compressive strength data werefitted to establish the relationship of the cube compressive strength and freeze-thaw cycles.By experiment to research in the content of chlorine ion in concrete specimen，according tothe Fick’s second law，the chloride ion diffusion coefficient was obtained. The test resultsshow that the concrete internal chloride ion concentration decreases with increasing depth，thechloride ion diffusion coefficient increases with increasing depth，and increase the trendgradually slows. According to the principle of concrete damage，and a correspondencerelationship between the elastic modulus and dynamic elastic modulus are established，therelationship four freeze-thaw medium the damage factor relative dynamic modulus ofelasticity loss rate relationship is established also. According to the chloride ion diffusioncoefficient in different depth and freezing and thawing cycle times，the establishment of adifferent depth the chloride ion diffusion coefficient and freezing and thawing cycle timesrelationship，combined damage factor and relative dynamic modulus of elasticity of therelationship，the relationship of the chloride ion diffusion coefficient and freeze-thaw cycles，and come to the relationship of the injury factor and the chloride ion diffusion coefficient.The concrete damage equation subjected to comprehensive effects of freeze-thaw cyclesand chloride ion diffusion could be more suitable to analyze the concrete structure in the cold region of the coast, which was enriched and developed the theory of concrete durability. Topredict the service life of concrete structures and the residual life also has the very vitalsignificance.