The Experts below are selected from a list of 72 Experts worldwide ranked by ideXlab platform
Sanghun Han - One of the best experts on this subject based on the ideXlab platform.
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microscopic influence of temperature on carbonation for Marine Concrete Structure
Journal of Korean Society of Coastal and Ocean Engineers, 2010Co-Authors: Sanghun HanAbstract:Some recent researches reported that high temperature rising decreases the carbonation depth of Concrete, which is contrary to the previous research results. Carbonation has been known as a reaction between calcium hydroxide and carbon dioxide. But a few researches showed that the other cement hydrates as well as calcium hydroxide react with carbon dioxide. This paper investigates the influence of temperature on carbonation and the variation of and by carbonation. In order to estimate the carbonation depth and the quantities of reactant and product of carbonation reaction, phenolphthalein testing and thermagravimetric analyzer test were conducted. The measurement of carbonation depth with temperature showed that the temperature increase from to C in carbonation environment makes the carbonation depth larger, but the increase from to has a small influence on the carbonation depth. Comparing calcium hydroxide and calcium carbonate with temperature, the quantity of of specimen carbonated at is greater than that of specimen carbonated at and the quantity of of specimen carbonated at is similar to that of specimen carbonated at . This observation shows that there is the optimum temperature increasing carbonation depth and the optimum temperature is close to .
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reliability analysis of chloride ion penetration based on level ii method for Marine Concrete Structure
Journal of the Korea institute for structural maintenance and inspection, 2008Co-Authors: Sanghun HanAbstract:Due to uncertainty of numerous variables in durability model, a probalistic approach is increasing. Monte Carlo simulation (Level III method) is an easily accessible method, but requires a lot of repeated operations. This paper evaluated the effectiveness of First Order Second Moment method (Level II method), which is more convenient and time saving method than MCS, to predict the corrosion initiation in harbor Concrete Structure. Mean Value First Order Second Moment method (MV FOSM) and Advanced First Order Second Moment method (AFOSM) are applied to the error function solution of Fick's second law modeling chloride diffusion. Reliability index and failure probability based on MV FOSM and AFOSM are compared with the results by MCS. The comparison showed that AFOSM and MCS predict the similar reliability index and MV FOSM underestimates the probability of corrosion initiation by chloride attack. Also, the sensitivity of variables in durability model to corrosion initiation probability was evaluated on the basis of AFOSM. The results showed that AFOSM is a simple and efficient method to estimate the probability of corrosion initiation in harbor Structures.
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analysis of chloride ion penetraion for Marine Concrete Structure with cyclic humidity environment
Ocean and Polar Research, 2004Co-Authors: Sanghun HanAbstract:The diffusion model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion model provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in situ analysis of chloride ion penetration for Marine Concrete Structures must be performed considering the cyclic humidity condition and the long term sorption.
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analysis of chloride ion penetration of Marine Concrete Structure
Journal of Korean Society of Coastal and Ocean Engineers, 2003Co-Authors: Sanghun Han, Useon Park, Donghyeon KimAbstract:The estimation functions were proposed for calculating diffusion coefficient, chloride binding, andevaporable water. The program estimating chloride ion penetration was developed on the basis of these functionsand the effects of humidity, curing temperature, water-cement ratio, and on chloride penetration were analyzed.The relative humidity increases the depth of chloride ion penetration and the trend becomes greater with aging.On the contrary, the influence of curing temperature on chloride ion penetraton decreases with aging. By the way,the rise of in cement increases total chloride concentration on the surface as the bound chloride concentra-tion increases but it decreases total chloride concentration on the inner part as the difusion velocity of frechloride decreases. The fal of water-cement ratio decreases the chloride penetration depth rapidly. Therefore, thereduction of water-cement ratio may be the most effective method for reducing of the stel corrosion by chloridepenetration.
Cccc Fourth - One of the best experts on this subject based on the ideXlab platform.
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The State of the Art of Durability Monitoring and Its Applications in Marine Concrete Structure
Guangdong Chemical Industry, 2013Co-Authors: Cccc FourthAbstract:The state of the art,technical characteristics,and applications of durability monitoring for Marine Concrete Structures were surveyed in the paper.The trend in development of the durability monitoring techniques was forecasted.It would provide references for the development of the durability monitoring technique.
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detection and assessment of Marine Concrete Structure based on prediction of durability service life
Port & Waterway Engineering, 2008Co-Authors: Haung Junzhe, Cccc FourthAbstract:Detection and assessment were carried out to the reinforced Concrete Structures′ durability based on relevant stipulations in the Detection and Assessment of Harbor and Marine Structures promulgated by the Ministry of Communications.The results conform to the actual situation,and can reflect the real working conditions of the wharf.
Jaejin Choi - One of the best experts on this subject based on the ideXlab platform.
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relationship between chloride diffusivity and the fundamental properties of Concrete
Journal of Korean Society of Hazard Mitigation, 2009Co-Authors: Doo-sun Choi, Jaejin ChoiAbstract:Marine Concrete Structure is exposed to salt injury and deteriorated by steel corrosion due to chloride ions diffusion. It, therefore, is very important to estimate the chloride diffusivity in Concrete. In this paper the compressive strength and permeable pore volume of Concrete are measured and the diffusion coefficient and penetration depth of chloride ions in Concrete were investigated to estimate the chloride diffusivity efficiently. To correlate these results each other, regression analysis was done. The results showed a good linear relation between chloride diffusivity and the fundamental properties of Concrete and the chloride diffusivity of Concrete with water-cement ratios of were about .
Yang Haichen - One of the best experts on this subject based on the ideXlab platform.
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exposure test on surface coating of Marine Concrete Structure in north china
China Harbour Engineering, 2014Co-Authors: Yang HaichenAbstract:Surface coating specimens that made according to coating system for Concrete Structure of Qingdao Bay Bridge were carried out exposure test. The anticorrosion performance and chloride ions resistance to seawater for surface coating had been analyzed in the frozen north sea environment. The research shows that surface coating has good protection and coating quality after 5 years, and the adhesive strength with Concrete surface is more than 2.5 MPa. Although the distance of 1 mm to 3 mm from Concrete surface penetrated a small amount of chloride ions, the chloride ions concentration reduced about 4 to 7 times comparing with the same depth of untreated Concrete. Surface coating can effectively reduce the chloride ion erosion and improve the service life of the Marine Concrete Structure.
Ling Ling Zhang - One of the best experts on this subject based on the ideXlab platform.
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Prediction of Chloride Diffusion in Concrete Structure Using Meshless Methods
Advances in Materials Science and Engineering, 2016Co-Authors: Ling Yao, Li Xiaolu, Ling Zhang, Ling Ling ZhangAbstract:Degradation of RC Structures due to chloride penetration followed by reinforcement corrosion is a serious problem in civil engineering. The numerical simulation methods at present mainly involve finite element methods (FEM), which are based on mesh generation. In this study, element-free Galerkin (EFG) and meshless weighted least squares (MWLS) methods are used to solve the problem of simulation of chloride diffusion in Concrete. The range of a scaling parameter is presented using numerical examples based on meshless methods. One- and two-dimensional numerical examples validated the effectiveness and accuracy of the two meshless methods by comparing results obtained by MWLS with results computed by EFG and FEM and results calculated by an analytical method. A good agreement is obtained among MWLS and EFG numerical simulations and the experimental data obtained from an existing Marine Concrete Structure. These results indicate that MWLS and EFG are reliable meshless methods that can be used for the prediction of chloride ingress in Concrete Structures.