Analysis And Study On Servicelife Of Marine Concrete Based On Long-term Data Accumulation At Home And Abroad

Chloride ion erosion is the main factor affecting the durability of concrete.Predicting the service life of reinforced concrete structures must rely on the long-term data of a large number of exposure stations and actual projects in order to make a practical theoretical analysis.Therefore,it is very important to study the evolution law of chloride ion diffusion parameters during the long-term service of coastal concrete structures.In this paper,through field research and experiments,the durability of concrete at the exposed stations of Dalian Port and Qinhuangdao was studied.Using the long-term data of actual projects and exposure stations at home and abroad,the long-term time-varying law of chloride ion diffusion coefficients of concrete in marine structures was studied.Exposed areas,exposed environments,and types of mineral admixtures in concrete were categorized to study the influencing factors of the chloride ion diffusion coefficient,and chloride ions were studied using the “ChaDuraLife V1.0 Predictive Model of Concrete Structure Life under Chlorine Environment and Computer Software”.The influence of time dependence of diffusion coefficient m on the life of concrete structures.The main conclusions are as follows:(1)On the basis of the 732 sets of data(49 of the Dalian port data,60 of the laboratory data,and 35 data of the Qinhuangdao exposure station)accumulated in this group over the past 20 years,21 countries at home and abroad were collected,including Asia(mainly Japan and South Korea)and Europe(mainly Germany,France,UK,Netherlands,Sweden,etc.),Australia,Iran,the United States,Canada,and various domestic exposure stations,the concrete chloride ion apparent diffusion coefficient data of 2481 groups of concrete exposed for various times in different regions(up to 97 years),systematically studied the different exposed areas on the table The effect of the time-varying law of chloride ion diffusion coefficient.It was found that the apparent diffusion coefficient of chloride ions showed a significant power-function decay relationship with the prolonged exposure time,and the value of the chlorine-diffusion coefficient's time-dependent constant,m,was somewhat different,suggesting that if the exposure time was the same,different exposures.The degree of chloride attack in the area is different.(2)Studying the effect of different exposure environments on the time-varying law of apparent chloride ion diffusion coefficient through a large amount of data at home and abroad.It was found that the time-varying effect of the dry-wet-alternate environmental concrete in the splash and tidal areas is the greatest,while the underwater area is stable.The erosive environment has little effect on the timevariation of the concrete,and a more accurate time-dependent constant m is obtained for each area.(3)The influence of concrete types on the time-varying law was studied,and the difference between the ordinary concrete and mineral admixture concrete m values was compared.It was found that appropriate addition of mineral admixtures can improve the resistance of concrete structures during longterm service.Chloride ion erosion performance,while the same type of concrete according to the exposure environment for more detailed classification study,to determine the more specific under different circumstances,the value of m rules.(4)Using ChaDuraLife V1.0 life model and software,the relationship between the life of concrete structures and the time-varying law was studied,and the influence of different m values on the service life of concrete was compared.The results show that the service life of concrete increases with the increase of m value.Therefore,the reasonable and correct value of m is related to the accuracy of the life analysis of the concrete structure,and even to the economy of the durability measures.(5)The analysis results of the life design of the research group and the European and American design models on the life design of marine concrete structures are compared.It is found that the calculation results of the lifespan of the Duracrete design model in Europe are contrary to the actual situation of marine engineering.The Life-365 design model of the United States is more stringent for the design of marine concrete structures and may lead to unnecessary additional fortification measures and increase project cost.The ChaDuraLife V1.0 life analysis model proposed by this research group considering the dual time-varying boundary conditions and diffusion coefficients is suitable for the life design of marine concrete structures,which is neither harsh nor safe.