Chloride-induced deterioration is the most important deterioration phenomenon in reinforced concrete structures in marine environments. When a crack occurs in cover concrete, it may initiate and accelerate corrosion of steel reinforcements embedded in the concrete. The performance of the reinforced concrete structure may subsequently decrease even in the early stage of its service life. With the aim to clarify the mechanism of chloride-induced deterioration, this paper reports the results of experimental investigation on chloride ion transportation in cracked concrete and proposes a simulation model for chloride ion transportation in cracked concrete. The zone affected by cracking was treated as the exposed surface of concrete in the proposed model, where chloride transportation was assumed to be governed by the concentration of the chloride ion solution in the crack. In addition, the effects of the crack width and an apparent diffusion coefficient through the cracks on chloride ion transportation were numerically investigated and the applicability of the proposed model was discussed.
This research is conducted to develop a model to predict the effective diffusion coefficients of substances (D e ) in concrete considering the spatial properties of composite materials. In this model, concrete is assumed to be composed of cement paste, an interfacial transition zone and aggregate, and the spatial properties of each material are considered with random arrangement of each material. D e in concrete is calculated based on the calculation results for the cement paste and interfacial transition zone. The proposed model can appropriately evaluate D e in concrete in previous research. The influence of the spatial properties of each composite material on the dispersion of D e is analytically investigated. The influence of cement particle arrangement is larger than that of fine and coarse aggregate, and the lower W/C , the greater that influence. Moreover, the influence of the interfacial transition zone on chloride ion diffusivity in concrete is also analyzed. This influence was found to be quite large, so that the interfacial transition zone should be taken into account for simulating diffusion in cementitious materials. In this model, the pore structure of cement paste is very simplified. Thus, it is necessary to examine the correspondence of the modeled pore structure and the actual pore structure.
The analytical flow simulation of flesh concrete is a recent challenge to researchers. Due to its heterogeneity, the concrete mix shows neither a perfectly viscous nor perfectly particulate behavior. However, the particulate behavior of fresh concrete flow like arching and blocking in pipes and in complex boundary conditions, is very common. This is further magnified due to high pressure in the case ofshotcreting. For the first time in shotcrete research, authors propose the application of the Distinct Element Method [1] (DEM) to predict particle behavior and amount of rebound loss, and to assess the quality of the shotcrete analytically, Also, the effect of an accelerating agent, the way its effect is modeled, effects of gradual change in shooting pressure, the resulting rebound is shown. The void of the attached concrete is also compared with that of normal cast concrete in an analytical way.
RI~SU MI ~
scite is a Brooklyn-based startup that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.