The effects of chemical attacks on physical and mechanical properties of concrete produced under cold weather conditions

Çullu, Mustafa; Arslan, Metin

doi:10.1016/j.conbuildmat.2014.01.072

Cited by 21 publications

(10 citation statements)

References 12 publications

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“…The physical/chemical interaction of sulfate attack is a complicated process and depends on many parameters, including concentration of sulfate ions, ambient temperature, amount of cement/mineral additives, water to cement ratio, diffusivity and/or permeability of concrete, and presence of supplementary pozzolanic admixtures [2,38,44]. Some effective methods that can eliminate negative effects of sulfate attack are presented as: 1) Mineral additions: The incorporation of ground granulated blast furnace slag into the cement is beneficial for the enhancement of diminution of expansion for concrete structure stored in sulfate solutions since slag will consume calcium hydroxide to some degree and lead to diminution of the gypsum and ettringite [45].…”

Section: Deterioration Caused By Sulfate Attackmentioning

confidence: 99%

Recent durability studies on concrete structure

Tang

Yao

Andrade

2015

Cement and Concrete Research

449

121

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Section: Deterioration Caused By Sulfate Attackmentioning

confidence: 99%

Recent durability studies on concrete structure

Tang

Yao

Andrade

2015

Cement and Concrete Research

449

121

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“…The formation of caustic alkalis was observed for mixes containing sodium nitrite and potash due to their reaction with Portland cement, thus excluding their application when reactive silica aggregates are used [1,28]. Concretes containing 1 wt% of an antifreeze admixture consisting of 30 wt% of calcium nitrate and 5 wt% of hydroxyethylamine reached a 28-day compressive strength between 28.42 MPa and 17.28 MPa while cured for 48 h at temperatures of 0 °C and −20 °C, respectively, followed by 26 days of water curing at room temperature [46,48]. Despite the favorable strength, the hardened concrete specimens exposed to corrosive environments of H2SO4 or NaCl with a 5% concentration for a period of 90 days at freezing temperatures showed detrimental effects.…”

Section: Opc-based Concretesmentioning

confidence: 99%

A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

et al. 2020

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Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

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“…Porém, como esse composto possui caráter expansivo, a medida que os volumes dos vazios não tiverem espaço suficiente para comportar os cristais de etringita, haverá uma expansão das fissuras já existentes até levar a perda das propriedades mecânicas, como observado no 30 | P á g i n a decréscimo dos valores de resistência à tração aos 90 dias, e perda da rigidez da pasta de cimento hidratada [11][12][13][14].…”

Section: Metodologiaunclassified

“…Os produtos liberados reagem com os compostos do cimento hidratado, gerando compostos com caráter expansivo, os quais ocasionam tensões internas no material, causando fissuração e degradação da estrutura, com redução nas propriedades mecânicas e perda da rigidez do concreto [12][13][14].…”

Section: Introductionunclassified

Efeito da adição de nanomagnetita (Fe3O4) em pastas de cimento Portland sujeitas ao ataque interno por sulfatos (ISA)

Pinkoski

Oliveira

Bragança

et al. 2017

Simpósio Paranaense De Patologia Das Construções

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Resumo: A vida útil de estruturas de concreto utilizadas na construção civil deve sempre ser prolongada, independentemente do ambiente em que estão contidas, mantendo as suas características, quando submetidas as solicitações mecânicas e frente aos agentes agressivos. Com uma grande presença de agentes que possibilitam a ocorrência de degradação, torna-se carente a interface de recuperação e manutenção dessas estruturas. As adições surgem como uma proposta para melhorar as propriedades do concreto e minimizar os efeitos nocivos aos quais as obras estão sujeitas. Nesta ocasião, foram testados seis traços diferentes de pastas de cimento, com e sem contaminação por pirita, com a adição de nanomagnetita em diferentes teores (de 0,5% a 1,0%) pela técnica de microscopia eletrônica de varredura (MEV) e pelo ensaio de resistência à tração por compressão axial. Com o aumento do teor de nanomagnetita na mistura, foi possível verificar uma microestrutura mais densa assim como um incremento da resistência mecânica (de cerca de 50% aos 7 dias) e a mitigação dos efeitos de degradação causados pelo presença do sulfeto mineral.Palavras-chave: Pasta de cimento, Pirita, Sulfato, nano-Fe3O4. Abstract:The life cycle of concrete structures used on civil construction must be always extended, regardless of the environment in which they are contained, keeping their characteristics while maintaining its ones, when submitted to the mechanical requests and against the aggressive agents. With a large presence of agents that allow the occurrence of degradation, the retrieval and maintenance interface of these structures becomes lacking. The additions are a proposal to improve these properties of concrete and minimize the harmful effects to which the works are subject. At this occasion, different traces of cement paste were tested, with and without pyrite contamination, with the addition of nanomagnetite in different percentages by scanning electron microscopy (SEM) technique and tensile strength by axial compression test. By increasing nanomagnetite percentage in the mixture, it was possible to verify a denser microstructure, as well as an enhance of the mechanical resistance and the mitigation of the degradation effects caused by the contaminant.

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The effects of chemical attacks on physical and mechanical properties of concrete produced under cold weather conditions

Cited by 21 publications

References 12 publications

Recent durability studies on concrete structure

Recent durability studies on concrete structure

A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Efeito da adição de nanomagnetita (Fe3O4) em pastas de cimento Portland sujeitas ao ataque interno por sulfatos (ISA)

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