Study On The Chloride Permeability Of Carbonated Concrete

With the high-speed development of society, the durability problem of concretestructure under horrible environment has been attention increasingly by human being.Nuclear power plant which is the special concrete structure has been stricter on itsdurability. However nuclear power plants of coastal area have been influence by all kindsof elements, such as carbonization and chloride ion erosion which is main point ofconcrete reinforcement corrosion. In environment of marine atmosphere, coupling ofcarbonization and chloride ion erosion increased degradation of nuclear power plant’sconcrete structure performance. Therefore, development research which is law ofchloride ion erosion from main concrete structure of nuclear power plant under marineatmosphere is quite important.The paper simulates the concrete structure of nuclear power plant among coastalmarine atmosphere situation, adopt Salt solution soaking and accelerated carbonationalternating wet-dry method, otherwise embed galvanized pipelines alternating reservedhole and pipelines of concrete structure by nuclear power plant in concrete sample, andproceed there wet-dry tests under three different cycle laws between concrete with orwithout pipelines, that measure its carbonation depth, chloride ion content, relativedynamic modulus and compressive strength.The results show that:(1) The diffusion law of chloride ion can be divided into threezones which called convection, diffusion and stable section by condition of concretesurface in by extension for concrete with or without pipelines; free chloride ion contentand total chloride ion content both exist linear relationship of concrete structure, namelyCt KCfand K is coefficient;(2) According to increasing times of wet-dry cycle forconcrete with or without pipelines, convection section of concrete structure elongate,carbonization depth of concrete structure increase, the value of coefficient K decrease;(3)The influence of carbonization to concrete focus on diffusion zone for concrete with orwithout pipeline, that either increase the peak value of diffusion coefficient from chlorideion, decrease chloride ion binding capacity of the concrete; or carbonization let micro concrete structure more densification, compressive strength will improve and relativedynamic modulus enlarge;(4) Carbonization binding capacity of concrete withoutpipeline is stronger than concrete with pipeline that coefficient K is greater than concretewith pipeline, but free chloride ion content of concrete with pipeline is a little more thanconcrete without pipeline.