Durability Reaserach Of Reinforced Concrete Under The Western Environment

With implementation of'the western development" strategy and"the Belt and Road Initiatives" strategy,the western region has a great develop in China.The scale of important infrastructure construction has a great expand in the western region.In the western region of China,the typical brine soil environment that harmful ions such as chloride ion,sulfate ion,magnesium ion and bicarbonate ion overproof seriously and climatic environment of large temperature difference betweenday and night make reinforced concrete structureservice in the harsh environment,and has seriously corrosion damage when far from the theoretical design service life.In this paper,the damaging process and the degradationlaw of reinforced concrete service in the western region under some harsh environmentsingle or couple effects such as brine,drying-wetting cycles,and stray current were researched,and service life prediction model of reinforced concrete structure was build.This provide scientifical theory for Enhancing Durability,Assessing Security,Predicting Servicelife and Quality Controling of reinforced concrete structure of the western engineering.In this paper,the influence law of some factors such as concrete strength(C30,C50),rebar type(smooth,protuberance),protection layer thickness(10mm,20mm),and corrosioninhibitor on durability of reinforced concrete under the western harsh environment was researched systematically by some test methods such as Linear PolarizationResistance,ElectrochemicalImpedance Spectroscopy,Precipitation-Potentiometric.The results show that,(1).Under the western harsh environment,All the factors have prominentinfluence on durability of reinforced concrete.The sequence of influence about above factors was concrete strength>protection layer thickness>rebar type>corrosioninhibitor under brine effect only.Under brine and drying-wetting cycles coupling effects,the sequence of influence was same,but degree of that have increased,it means drying-wetting cycles effect accelerate the damaging process.Under stray current and brine coupling effects,allthe specimens' corrosion resistance were reduced by orders of magnitudesas and depicted sharp reduction in the initialstage,the plain rebars' corrosion resistance is 2.5 times than ribbed rebars in concrete,corrosioninhibitorcan improves corrosion resistance up to 50%.(2).After brine soil environment corrosion,the chloride ion content in concrete around the rebar show a regulardistribution,concrete strength and protection layer thickness have a great influence on distribution of chloride ion content,rebar type and corrosioninhibitor have a weak influence on that,and the weak influence appear in the later stage.1.2%-1.5%can be got as the critical concentration of the chloride ion in concrete when rebar corrosion take place by mass data.(3).The transformationlaw of micro-structure of concrete and rebarhas in-situ observe by X-CT during rapid corrosion process,and pitting phenomenon appeared at 4 hour,corrosion pits and corrosion products appeared at 24 hour.(4).Based on numericalmethods,the service life prediction model of reinforced concrete under the western harsh environmentwas established in this paper,which showed a better applicability based on verification results of some cases.