C-D-c-t diagrams for practical design of concrete durability parameters

Bjegović, Dubravka; Krstić, Vedrana; Mikulić, Dunja; Ukrainczyk, Velimir

doi:10.1016/0008-8846(94)00126-j

Cited by 10 publications

(6 citation statements)

References 2 publications

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“…Ele foi produzido para projetar novas estruturas, baseando-se em critérios de durabilidade, ou para calcular a vida útil residual de estruturas existentes, por meio de quatro formas diferentes (diferenciando-se pelas variáveis de entrada e saída). O coeficiente D pode ser calculado por meio de equação, conforme a relação água/ligante (a/l) e o tipo de cimento estudado [41]. Não se teve acesso a esse programa na web e nem maiores informações sobre o modelo no site da instituição; portanto, provavelmente é de uso interno para pesquisa.…”

Section: Coeficiente De Difusão E Concentração Superficial Dependente...unclassified

Modelos preditivos de vida útil de estruturas de concreto sujeitas à iniciação da corrosão de armaduras por cloretos: contribuição ao estado da arte por meio de revisão sistemática da literatura – Parte 2

2022

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RESUMO Vários modelos para predição de vida útil de estruturas de concreto armado simulam o ingresso de agentes agressivos, como os cloretos, geralmente baseados em leis de difusão modificadas ou em propostas de transporte de multi espécies, considerando diversos parâmetros. Sua aplicação pode aprimorar a eficiência e a otimização do projeto e da vida útil em serviço de estruturas em concreto armado. O presente artigo contempla a parte 2 de resultados de uma Revisão Sistemática da Literatura (RSL) com o objetivo de descrever, analisar e classificar os modelos selecionados em determinísticos ou probabilísticos e em empíricos, analíticos e/ou numéricos. Como resultado, observou-se que a maioria dos modelos considerados é baseada na Segunda Lei de Fick, modificada ou não. Além disso, 72% deles são analíticos. Entre os probabilísticos, o método numérico mais utilizado foi a simulação de Monte Carlo. Adicionalmente, outras análises foram realizadas, como os métodos para o cálculo do coeficiente de difusão (D), os teores críticos (Ccr) utilizados, a forma de consideração da não saturação do concreto, fixação de cloretos, fissuras, a direção de penetração dos cloretos, entre outros. Apesar de todos os modelos serem uma simplificação da realidade, trazendo algumas ponderações e limitações, observou-se uma evolução dessas ferramentas para maiores níveis de complexidade.

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Section: Coeficiente De Difusão E Concentração Superficial Dependente...unclassified

Modelos preditivos de vida útil de estruturas de concreto sujeitas à iniciação da corrosão de armaduras por cloretos: contribuição ao estado da arte por meio de revisão sistemática da literatura – Parte 2

2022

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“…Minerals processing makes use of solid-liquid mixing operations in various stages, thus, making it one of the major fields of solid-liquid mixing applications (Ayranci et al, 2010).For efficient interactions of solids and liquids, solid-liquid mixing finds great importance in mineral processing as the slurries contain high solids loading with different mineral compositions. The concrete production industry is another area where mixing plays a vital role (Bjegovic et al, 1995). Guo et al (2014) studied effects of solid-liquid mixing on microstructure of semi solid A356 aluminium alloy.…”

Section: Applicationsmentioning

confidence: 99%

Using tomography and computational fluid dynamics to study the performance of a maxblend impeller for solid-liquid mixing operations

Mishra¹

2021

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A thorough literature review suggests that no comprehensive research work has been done regarding the characterization of the local solid concentrations in a slurry reactor equipped with a Maxblend impeller. The aim of this research work was to assess the mixing performance of a Maxblend impeller in a slurry reactor through electrical resistance tomography (ERT) and computational fluid dynamics (CFD). The mixing efficiency of the Maxblend impeller for solid-liquid mixing operation was compared to those measured for the A200 (an axial-flow impeller) and the Rushton turbine (a radial-flow impeller). The tomography images were employed to assess the particles distribution inside the slurry reactor. The CFD model was created using the Eulerian and Eulerian (E-E) method, standard k-ε turbulence model, and sliding mesh (SM) technique for simulating the two-phase fluid flow, turbulence effects, and stirrer rotation, respectively. The validated CFD model was utilized to obtain the particle concentration profiles and to determine the local particle distributions attained by the Maxblend impeller. The data were utilized to analyze the impacts of various important parameters such as the agitation speed, particle concentration, particle diameter, specific gravity of the particle, and the use of baffles on the mixing efficiency of the Maxblend impeller in terms of the extent of homogeneity and mixing index. The particle distribution in the slurry reactor furnished with a Maxblend impeller was also assessed through clouding height and just suspended agitation speed approaches in this study. The results from this study showed that the assessment of the optimum impeller speed is extremely important to enhance the local mixing quality in the mixing vessel. Experimental tests demonstrated that maximum homogeneity attained by the Maxblend impeller was higher than those for the A200 and Rushton impellers.

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“…Empirical models arrived after 1990's clearly established the relationship and the dependency of chloride diffusion values with time and exposure condition, confirming that the chloride diffusion does not solely depend on the characteristics of the material used for the structures. Ultimately, a power function was arrived at and used by several researchers as given by Equation (3) [32][33][34][35][36].…”

Section: Evolution Of Service Life Prediction Models and Influence Ofmentioning

confidence: 99%

Influence of chloride threshold value in service life prediction of reinforced concrete structures

et al. 2018

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Extensive studies have been reported on the development of service-life prediction of reinforced concrete structures in the last two decades. Service life of a reinforced concrete structure is dependent on the corrosion process, specifically chloride threshold value. Chloride threshold value is a distinctive property and is dependent on several factors such as the supplementary cementitious material used, presence of surface cracks, water to binder ratio, type of steel reinforcement, exposure conditions, measurement methods, etc. Although chloride threshold value is an influential parameter in service-life prediction, a definitive chloride threshold value considering these factors is not reported in the existing literature and standards. Moreover, values adopted in many analytical tools for service life predictions based on the type of steel reinforcement alone are not appropriate and leads to inaccurate calculations. There is a gap in the available literature in understanding the selection of suitable chloride threshold values to be adopted for a specific system. Therefore, it is imperative to study the variation of chloride threshold value with exposure conditions as well as other influencing parameters, to achieve proper service life prediction. In the paper, several influencing parameters on chloride threshold value and its significance on prediction method are comprehensively reviewed. Moreover, suitable recommendations are highlighted for Indian and international standards at the later part of the study.

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C-D-c-t diagrams for practical design of concrete durability parameters

Cited by 10 publications

References 2 publications

Modelos preditivos de vida útil de estruturas de concreto sujeitas à iniciação da corrosão de armaduras por cloretos: contribuição ao estado da arte por meio de revisão sistemática da literatura – Parte 2

Modelos preditivos de vida útil de estruturas de concreto sujeitas à iniciação da corrosão de armaduras por cloretos: contribuição ao estado da arte por meio de revisão sistemática da literatura – Parte 2

Using tomography and computational fluid dynamics to study the performance of a maxblend impeller for solid-liquid mixing operations

Influence of chloride threshold value in service life prediction of reinforced concrete structures

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