Influência do tempo máximo de mistura e transporte especificado pela ABNT NBR 7212:2012 na resistência a compressão de concretos usinados

Barboza, Lucas da Silva; Gonçalves, Eliseu Cunha; Santos, Tarcila Malena Souza dos; Sartorti, Artur Lenz

doi:10.18256/2358-6508.2017.v4i2.2075

Cited by 3 publications

(4 citation statements)

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“…The increase in the water/cement ratio (w/c) modifies the mechanical properties of the concrete, causing the formation of voids that decrease the mechanical strength. When there is an excess of water added to the mixture, it may not meet the pre-established parameters for application (BARBOZA, et. al., 2017).…”

Section: Technological Control Of Concrete and Its Barriersmentioning

confidence: 99%

Manual on risks associated with lack of knowledge and lack of standardization in the use of ready-mixed concrete in construction sites: A useful tool for the user

Oliveira,

Souza Junior

et al. 2024

Navigating Through the Knowledge of Education

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Ready-mixed concrete is a product that has been widely applied in civil constructions, as they offer some advantages such as reducing the execution time of the work and better-quality control in the concrete manufacturing processes have better quality. Its choice is based on properties such as compressive strength (fck), water/cement factor (w/c), minimum cement consumption per m³ (kg/m³), slump, durability, setting time, among others. To obtain the desired properties for the machined concrete, there is a need for technological control, which covers everything from the choice of component materials to the stages of thickening and curing the concrete. There are standardized procedures for both the concrete company and the professionals involved with the application of ready-mixed concrete. With the growth of the city of Poços de Caldas in recent years, there is a tendency to increase the occurrences related to failures during concreting in small and medium-sized works, in line with the lack of professionals with knowledge and experience that provide better technological control. These possibilities can cause insecurity for future residents, with the appearance of pathologies and even accidents. In view of the above, this work aimed to prepare a practical guidance manual for the general population, with emphasis on the owners who hire the services of the concrete company and the technical managers, to guide them on the actions, control, and responsibilities during the receipt/use of machined concrete.

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Section: Technological Control Of Concrete and Its Barriersmentioning

confidence: 99%

Manual on risks associated with lack of knowledge and lack of standardization in the use of ready-mixed concrete in construction sites: A useful tool for the user

Oliveira,

Souza Junior

et al. 2024

Navigating Through the Knowledge of Education

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show abstract

“…Ou seja, o aditivo é ideal para manter-se na consistência desejada sem que prejudique a resistência característica do concreto. Essas evidências também foram verificadas por [27].…”

Section: Discussõesunclassified

“…Diversas pesquisas sobre o uso de aditivos redutores de água em materiais cimentícios analisam as vantagens e as desvantagens de sua utilização nos concretos [5,8,27]. Os aditivos redutores podem ser utilizados em substituição à água para correção do abatimento ao longo do tempo [11,30].…”

Section: Introductionunclassified

Estudo das propriedades do concreto convencional com aditivo ou adição de água para correção de consistência

2020

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RESUMO A fluidez e a plasticidade do concreto devem ser mantidas durante o deslocamento até a obra, impedindo possíveis modificações nas propriedades. Quando há alterações, devem ser corrigidas com água ou aditivos plastificantes. Portanto, esse artigo tem como objetivo avaliar as propriedades de fluidez e resistência característica do concreto. Para isso, produziram-se concretos com fck de 25MPa e consistência S50. A análise dos resultados deu-se a partir de três experimentos realizados, sendo um sem a correção do Slump Test, o segundo com as verificações de consistência nos tempos de 60, 120 e 150 minutos, logo após o preparo da mistura. Já o terceiro, a verificação consiste no concreto com as mesmas verificações que o segundo, mas, com a adição do aditivo plastificante. Os resultados obtidos apontam que no traço de referência houve minimização da consistência em 64% ao decorrer dos 150 minutos. A média da resistência à compressão reduziu ao longo do tempo, ao passo que se adicionava água. Logo, a resistência característica caiu em média 7,25% com relação ao concreto sem a correção do Slump. No entanto, para o concreto com aditivo, a resistência média teve um aumento de 16,52% durante os 150 minutos. Isso remete ao fato de que o uso de aditivos nos percentuais analisados favorece ao ganho de resistência do concreto. Por outro lado, ao adicionarmos água, o concreto perde resistência. Logo, o uso de água para correção da fluidez não é o ideal, uma vez que altera a resistência final do concreto.

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“…Admixtures may also be employed in order to provide special properties to the product [1,2]. Homogeneity and cohesion that provide workability and the required resistance to the material are factors directly associated to materials dosage and mixture [3,5]. Thus, seeking for better practicality, economy and quality in constructions through rationalized processes, most concrete consumed in Brazil comes from plants with dosage centrals [5,7].…”

Section: Introductionmentioning

confidence: 99%

Influence of Water Addition to Correct the Slump in Compressive Strength of Concrete Produced in Sinop - Brazil

Almeida¹,

Scariot²,

Nunes³

et al. 2018

ijme

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The combination of hot weather typical factors, such as high temperature and low relative humidity of the air, associated with the delay in concrete application due to lack of planning in concreting, are some causes of slump loss in this material. Depending on the type of work and the adopted execution methods, this loss may make both placement and compaction more difficult. Thus, consistency correction through water addition or other plasticizer additives are common. In this context, this research aimed to analyze the variations of slump loss in concrete through time and the consequences of water addition in the mixture. Therefore, it was performed a study with trace of characteristic resistance to compression correspondent to 35 MPa, analyzing 70 test specimens in a total of seven subsequent periods, from 0 min (after preparation) and 180 min. The specimens were molded according to ABNT NBR 5738 (2015) Brazilian standard and submitted to compression test after 28 days being cured, according to ABNT NBR 5739 (2018) Brazilian standard. Results showed that after 180 min, water addition caused a 68,60% increase in water to cement ratio and a 59,20% loss of resistance to compression. In summary, water addition to slump correction was observed to be an extremely harmful practice to concrete and it should be avoided or minimized.

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Influência do tempo máximo de mistura e transporte especificado pela ABNT NBR 7212:2012 na resistência a compressão de concretos usinados

Cited by 3 publications

References 0 publications

Manual on risks associated with lack of knowledge and lack of standardization in the use of ready-mixed concrete in construction sites: A useful tool for the user

Manual on risks associated with lack of knowledge and lack of standardization in the use of ready-mixed concrete in construction sites: A useful tool for the user

Estudo das propriedades do concreto convencional com aditivo ou adição de água para correção de consistência

Influence of Water Addition to Correct the Slump in Compressive Strength of Concrete Produced in Sinop - Brazil

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