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Meso-scale modeling of chloride diffusion in concrete with consideration of effects of time and temperature 被引量:4
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作者 Li-cheng WANG tamon ueda 《Water Science and Engineering》 EI CAS 2009年第3期58-70,共13页
A meso-scale truss network model was developed to predict chloride diffusion in concrete. The model regards concrete as a three-phase composite of mortar matrix, coarse aggregates, and the interfacial transition zone ... A meso-scale truss network model was developed to predict chloride diffusion in concrete. The model regards concrete as a three-phase composite of mortar matrix, coarse aggregates, and the interfacial transition zone (ITZ) between the mortar matrix and the aggregates. The diffusion coefficient of chloride in the mortar and the ITZ can be analytically determined with only the water-to-cement ratio and volume fraction of fine aggregates. Fick's second law of diffusion was used as the governing equation for chloride diffusion in a homogenous medium (e.g., mortar); it was discretized and applied to the truss network model. The solution procedure of the truss network model based on the diffusion law and the meso-scale composite structure of concrete is outlined. Additionally, the dependence of the diffusion coefficient of chloride in the mortar and the ITZ on exposure duration and temperature is taken into account to illustrate their effect on chloride diffusion coefficient. The numerical results show that the exposure duration and environmental temperature play important roles in the diffusion rate of chloride ions in concrete. It is also concluded that the meso-scale truss network model can be applied to chloride transport analysis of damaged (or cracked) concrete. 展开更多
关键词 meso-scale modeling CONCRETE chloride diffusion truss network model
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Material Mechanical Properties Necessary for the Structural Intervention of Concrete Structures
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作者 tamon ueda 《Engineering》 SCIE EI 2019年第6期1131-1138,共8页
Structural intervention involves the restoration and/or upgrading of the mechanical performances of structures. In addition to concrete and steel, which are typical materials for concrete structures, various ber-reinf... Structural intervention involves the restoration and/or upgrading of the mechanical performances of structures. In addition to concrete and steel, which are typical materials for concrete structures, various ber-reinforced polymers (FRPs), cementitious materials with bers, polymers, and adhesives are often applied for structural intervention. In order to predict structural performance, it is necessary to develop a generic method that is applicable to not only to steel, but also to other materials. Such a generic model could provide information on the mechanical properties required to improve the structural performance. External bonding, which is a typical scheme for structural intervention, is not applied for new structures. It is necessary to clarify material properties and structural details in order to achieve better bonding strength at the interface between the substrate concrete and an externally bonded material. This paper presents the mechanical properties of substrate concrete and relevant intervention material for the fol- lowing purposes: ① to achieve better shear strength and ultimate deformation of a member after struc- tural intervention;and ② to achieve better debonding strength for external bonding. This paper concludes that some of the mechanical properties and structural details for intervention materials that are necessary for improvement in mechanical performance in structures with structural intervention are new, and differ from those of structures without intervention. For example, high strength and stiff- ness are important properties for materials in structures without structural intervention, whereas high fracturing strain and low stiffness are important properties for structural intervention materials. 展开更多
关键词 Structural intervention High fracturing strain No yielding Low stiffness ROUGHNESS Fiber-reinforced polymer Polymers
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