Rapid testing method for segregation resistance of self-compacting concrete

Bui, Van Khoa; Montgomery, Denis; Hinczak, I; Turner, Kenneth A.

doi:10.1016/s0008-8846(02)00811-6

Cited by 85 publications

(34 citation statements)

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“…Qualitativa é por inspeção visual após o ensaio de espalhamento do concreto, que consiste em verificar a existência de anel de exsudação e uma maior concentração de agregado graúdo na região central do concreto espalhado [43]. De forma quantitativa, pode-se citar os ensaios de coluna de segregação [45], settlement column [46], penetration apparatus [47], segregation probe [48], flow trough [49] e sieve stability [43]. CUSSIGH [50] afirma que o ensaio de coluna de segregação é o mais adequado para se notar diferenças entre diferentes misturas de CAA o que é corroborado pelo grande uso desse ensaio em várias normas internacionais.…”

Section: Aspectos Relevantes De Autoadensabilidade E De Reologia De Aunclassified

Avaliação dos parâmetros de autoadensabilidade e de reologia do concreto autoadensável

2017

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RESUMOO concreto autoadensável é de complexa obtenção, por isso exige-se um estudo minucioso da mistura e do seu comportamento no estado fresco. De acordo com os requisitos de autoadensabilidade exigidos pela norma brasileira ABNT NBR 15823-1, decidiu-se obter parâmetros de autoadensabilidade e de reologia por meio de estudos em argamassas e, posteriormente, estudos em concretos. Os parâmetros decorrentes da avaliação das argamassas foram obtidos por meio dos seguintes ensaios: mini-slump, mini-funil e caracterização reológica por meio do reômetro da marca Rheotest N4.1. Os parâmetros provenientes da avaliação dos concretos foram obtidos por meio dos ensaios e modelos matemáticos: slump flow, T500, funil V, anel J, caixa L, caixa U, tubo de segregação, parâmetros reológicos estimados por meio de equações matemáticas propostas por Sedran e De Larrard. Com esses parâmetros, foi possível parametrizar ou mapear os concretos autoadensáveis com vistas na norma NBR 15823, bem como foi feita uma avaliação do emprego da classificação dessa norma para o concreto autoadensável. Constatou-se, por exemplo, que o ensaio T500 não apresentou resultados consistentes de viscosidade plástica aparente quando comparados com os resultados do ensaio de Funil V para esta mesma característica. Verificou-se que os ensaios que avaliam habilidade passante, tais como, caixa L e anel J não demonstraram uma boa relação entre seus resultados, assim podendo comprometer a classificação do concreto como autoadensável. Por fim, de maneira geral, observou-se uma importante relação dos parâmetros de autoadensabilidade e de reologia de argamassas e de concretos e, além disso, despertou-se no sentido de melhor avaliar a autoadensabilidade do concreto diante de algumas inconsistências nos resultados de alguns ensaios.Palavras-chave: concreto autoadensável, argamassa, habilidade passante, capacidade passante, resistência à segregação. ABSTRACTThe design of self-compacting concrete is complex, so it requires a thorough study of the mixture and their behavior in the fresh state. According to workability requirements required by the Brazilian standard NBR 15823-1, we decided to get workability parameters and rheology through studies in mortars, and later studies in concrete. The parameters resulting from the evaluation of the mortars were obtained by means of the following tests: mini-slump, mini funnel and rheological characterization using the rheometer of Rheotest N4.1 brand. The parameters resulting from the evaluation of concrete were obtained through the tests and mathematical models: slump flow, T500, V funnel, J ring, L box, U box, segregation tube, rheological parameters estimated by mathematical equations proposed by Sedran and De Larrard. From these parameters, it was possible to parameterize or map the self-compacting concrete according NBR 15823-1, and an assessment was made of the use of this classification standard for self-compacting concrete. It was found, for example, that the T500 test results showed no apparent consistent plastic viscos...

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Section: Aspectos Relevantes De Autoadensabilidade E De Reologia De Aunclassified

Avaliação dos parâmetros de autoadensabilidade e de reologia do concreto autoadensável

2017

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“…Numerous L-boxes of widely different dimensions have been tried. Bui et al; The common experience of researchers in regards to robustness of selfconsolidating concrete (SCC) has been that when mixing, the overall margins in production are smaller. It has been observed (Emborg, 2000;Nishizaki et al, 1999) that SCC is more sensitive to any deviation from target recipe and from mixing techniques than ordinary concrete.…”

Section: L-box Testmentioning

confidence: 99%

“…Numerous L-boxes of widely different dimensions have been tried. Bui et al; The physical and chemical properties and the amounts of concrete ingredients affect the rheological behavior, stability, flowability and segregation resistance of SCC (Tattersall, 1991). Typically SCC is designed in such a way that all the required properties are met with optimal usage of constituent materials.…”

Section: L-box Testmentioning

confidence: 99%

Dowel Bar Retrofit Mix Design and Specification

Deshpande¹,

Olek²

2008

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JOINT TRANSPORTATION RESEARCH PROGRAMThe Joint Transportation Research Program serves as a vehicle for INDOT collaboration with higher education institutions and industry in Indiana to facilitate innovation that results in continuous improvement in the planning, design, construchttps://engineering.purdue.edu/JTRP/index_html Supplementary NotesPrepared in cooperation with the Indiana Department of Transportation and Federal Highway Administration. AbstractThe focus of this project was on identifying critical properties that control long term performance of repair concrete, especially rapid setting materials extended using pea gravel (maximum size aggregate 9.5 mm).In the first phase of this project, four commercial rapid setting materials (CRSMs) were selected and development of mixture proportions in terms of optimum pea gravel content and water content was performed. Optimized mixtures were further evaluated at three different initial temperature conditions. The properties evaluated included workability, setting time, rate of compressive strength developed, slant shear bond strength, freeze thaw resistance, air void system characteristics of hardened concrete, drying shrinkage and cracking potential. It was observed that some of the CRSMs evaluated did not meet requirements of ASTM C 928. All, except one, CRSMs tested exhibited low resistance to freezing and thawing but all had high resistance to cracking.In the second phase of the project, rapid setting self consolidating concrete (RSSCC) was developed using ternary blend of cementitious materials, high range water reducer (HRWR) and accelerators. Slump flow, visual stability index (VSI), compressive strength at various ages and the power consumption values for the mortar mixer indicated that a five minutes mixing sequence involving a 2Step addition of HRWR produces stable RSSCC mixture. The results of various tests carried out indicate that it is possible to develop a small aggregate size based self consolidating repair concrete that achieves a compressive strength of 19 MPa at the end of 6 hrs, has good bond characteristics and excellent freezing and thawing durability (DF>90%).The sensitivity of RSSCC to aggregate characteristics and production variables was also evaluated. Specifically, the influence of aggregate gradation and aggregate moisture content using different types of mixers and re mixing after a period of rest was evaluated. It was observed that variation in aggregate moisture content and aggregate gradation resulted in noticeable changes in fresh concrete properties such as the slump flow, stability and V funnel flow values. While changes in moisture content and gradation of aggregates had an impact on the early (6 h) compressive strength, the compressive strength at the end of 24 hours was not significantly affected. Key Wordsdowel bars, rapid setting repair materials, self consolidating concrete, durability Distribution StatementNo restrictions. This document is available to the public through the National Technical Information Service, Spri...

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“…Dentro del primer grupo hay muchos tipos (6,10,11,12,13), algunos de los cuales se basan en establecer la resistencia a la segregación en función de las propiedades reológicas del material. No obstante, los resultados que se obtienen con estos últimos son algo contradictorios, alcanzándose buenas correlaciones en unos casos (14) y malas en otros (7,15,16).…”

Section: Introductionunclassified

“…Ante la necesidad de evaluar con criterios objetivos la resistencia a la segregación de un HAC, uno de los planteamientos más comúnmente establecidos es estudiar la variación de árido grueso con la altura. Para ello se han ideado numerosos ensayos, donde las diferencias más importantes entre unos y otros estriban fundamentalmente en la forma y dimensiones de los moldes empleados (7,12,14,16,17,18).…”

Section: Introductionunclassified

Homogeneidad de los hormigones autocompactantes

2007

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RESUMENEn este trabajo se estudia la homogeneidad de los hormigones autocompactantes en piezas hormigonadas verticalmente, determinando su resistencia a la segregación y la uniformidad de su estructura porosa, dado que la pér-dida de estabilidad de una mezcla puede conducir a una distribución no uniforme de sus propiedades. Para ello se han fabricado dos tipos de hormigones, uno autocompactante y otro tradicional vibrado, con diferentes relaciones a/c y distintos tipos de cemento. Los resultados ponen de manifiesto que los hormigones autocompactantes presentan una buena resistencia a la segregación, aunque algo menor que la registrada en los hormigones tradicionales. A pesar de ello, su estructura porosa tiende a ser ligeramente más uniforme, debido probablemente a un menor sangrado. Asimismo, presentan una mayor densidad aparente, una menor porosidad y un menor tamaño medio de poro, lo que les confiere mejores prestaciones frente a la penetración de agua bajo presión. Ahora bien, para diá-metros de poro superiores aproximadamente a 0,5 µm, la distribución de tamaños de poro es similar a la de los hormigones tradicionales, dando lugar a una absorción también similar.Palabras clave: hormigón autocompactante, segregación, porosidad, absorción, permeabilidad. SUMMARYConcrete instability may lead to the non-uniform distribution of its properties. The homogeneity of self-consolidating concrete in vertically cast members was therefore explored in this study, analyzing both resistance to segregation and pore structure uniformity. To this end, two series of concretes were prepared, self-consolidating and traditional vibrated materials, with different w/c ratios and types of cement. The results showed that selfconsolidating concretes exhibit high resistance to segregation, albeit slightly lower than found in the traditional mixtures. The pore structure in the former, however, tended to be slightly more uniform, probably as a result of less intense bleeding. Such concretes are also characterized by greater bulk density, lower porosity and smaller mean pore size, which translates into a higher resistance to pressurized water. For pore diameters of over about 0.5 µm, however, the pore size distribution was found to be similar to the distribution in traditional concretes, with similar absorption rates. Key yw wor rds: self-consolidating concrete, segregation, porosity, absorption, permeability. Persona de contacto/Corresponding author: mvalcuen@csa.upv.es INTRODUCCIÓNEl hormigón autocompactante (HAC) puede definirse como aquel que es capaz de fluir en el interior del encofrado, pasando entre las armaduras y consolidándose úni-camente bajo la acción de su propio peso, sin necesidad de compactación y sin presentar segregación o exudación.Una de las dificultades que plantea la fabricación de este tipo de hormigones es la estabilidad de la mezcla, pues a medida que aumenta la fluidez del material, su resistencia a la segregación disminuye, y puede dar lugar durante el vertido a bloqueos de los áridos al pasar por zonas congestio...

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Rapid testing method for segregation resistance of self-compacting concrete

Cited by 85 publications

References 1 publication

Avaliação dos parâmetros de autoadensabilidade e de reologia do concreto autoadensável

Avaliação dos parâmetros de autoadensabilidade e de reologia do concreto autoadensável

Dowel Bar Retrofit Mix Design and Specification

Homogeneidad de los hormigones autocompactantes

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