Behaviour of cement concrete at high temperature

Hager, Izabela

doi:10.2478/bpasts-2013-0013

Cited by 242 publications

(261 citation statements)

References 19 publications

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“…At high temperatures, various physical (phase expansion, condensation, evaporation and vapor diffusion), chemical (thermo-chemical damage and dehydration) and mechanical (thermo-mechanical damage, spalling and cracking) phenomena take place in concrete that results in deterioration of its properties (Heikal 2000). As temperature is increased, the water on the surface of concrete and the capillary water is lost, and this process is accelerated by the reduced cohesive forces between water molecules due to water expansion (Hager 2013). At a temperature of 105°C, the free water starts evaporating rapidly.…”

Section: Introductionmentioning

confidence: 99%

“…At a temperature of 105°C, the free water starts evaporating rapidly. In the temperature range from 80 to 150°C, dehydration of ettringite takes place followed by the decomposition of gypsum between 150 and 170°C (Hager 2013). When the temperature reaches to 300°C, the chemically bound water starts to evaporate, which in turn decreases the compressive strength of concrete.…”

Section: Introductionmentioning

confidence: 99%

“…When temperature increases beyond 400°C, the concrete strength decreases more rapidly due to the degradation of calcium-silica-hydrate (C-S-H). Second phase of the C-S-H decomposes in the temperature range from 600 to 800°C forming b-C 2 S (Hager 2013). At a temperature of 900°C, the C-S-H breaks down completely.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete

Tufail

Shahzada

Gencturk

et al. 2016

Int J Concr Struct Mater

150

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Although concrete is a noncombustible material, high temperatures such as those experienced during a fire have a negative effect on the mechanical properties. This paper studies the effect of elevated temperatures on the mechanical properties of limestone, quartzite and granite concrete. Samples from three different concrete mixes with limestone, quartzite and granite coarse aggregates were prepared. The test samples were subjected to temperatures ranging from 25 to 650°C for a duration of 2 h. Mechanical properties of concrete including the compressive and tensile strength, modulus of elasticity, and ultimate strain in compression were obtained. Effects of temperature on resistance to degradation, thermal expansion and phase compositions of the aggregates were investigated. The results indicated that the mechanical properties of concrete are largely affected from elevated temperatures and the type of coarse aggregate used. The compressive and split tensile strength, and modulus of elasticity decreased with increasing temperature, while the ultimate strain in compression increased. Concrete made of granite coarse aggregate showed higher mechanical properties at all temperatures, followed by quartzite and limestone concretes. In addition to decomposition of cement paste, the imparity in thermal expansion behavior between cement paste and aggregates, and degradation and phase decomposition (and/or transition) of aggregates under high temperature were considered as main factors impacting the mechanical properties of concrete. The novelty of this research stems from the fact that three different aggregate types are comparatively evaluated, mechanisms are systemically analyzed, and empirical relationships are established to predict the residual compressive and tensile strength, elastic modulus, and ultimate compressive strain for concretes subjected to high temperatures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete

Tufail

Shahzada

Gencturk

et al. 2016

Int J Concr Struct Mater

150

View full text Add to dashboard Cite

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“…Já as alterações físicas são promovidas pelo aparecimento de fissuras e a ocorrência do desplacamento do material. [7,8].…”

Section: Introductionunclassified

Avaliação da resistência residual de lajes alveolares em concreto armado em uma edificação industrial após incêndio

et al. 2017

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RESUMOO concreto, durante exposição a elevadas temperaturas, caracteriza-se pela baixa difusividade térmica e incombustibilidade, resultando em desempenho satisfatório frente ao fogo. Todavia, constatam-se transformações químicas e físicas em seus componentes. A estabilidade do composto relaciona-se com a microestrutura, portanto consegue-se verificar a degradação do material através de técnicas avançadas de análise microestrutural. Neste contexto, o uso de ensaios no material, como a difratometria e fluorescência de raios X, mostrase atraente. Neste artigo, é descrita a inspeção de laje alveolar pré-fabricada de uma edificação industrial, a qual sofreu exposição às altas temperaturas provindas de um incêndio no subsolo da edificação. Avaliou-se o elemento estrutural através de ensaios de caracterização química, em diferentes espessuras da laje de concreto, estimando a temperatura alcançada em cada camada e, consequentemente, a perda de resistência do elemento estrutural. A partir dos resultados, constatou-se a temperatura de, aproximadamente, 700 ºC na superfície da laje e menos de 100 ºC nas camadas mais profundas. Estimou-se a redução na resistência à compressão do concreto na ordem de 25 % na camada de 20 mm e redução praticamente desprezável na região dos fios protendidos, atestando a segurança estrutural da estrutura após o sinistro. Palavras-chave:Concreto. Altas temperaturas. Resistência residual. Difração por raios-x. Fluorescência de raios x. ABSTRACTConcrete, during exposure to elevated temperatures, is characterized by low thermal diffusivity and incombustibility, resulting a satisfactory performance against fire. However, chemical and physical changes occur in its components. The stability of the compound relates to its microstructure, so it is possible to verify the material degradation using advanced techniques of microstructural analyses. In this context, the use of mate-

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“…The primary parameter taken into account while designing concrete compositions is the w/c (w/b) ratio [2][3][4]. According to PN-EN 206, fly ash, silica fume, and ground granulated blast furnace slag can be taken into account in the cement content and water/cement (w/c) ratio, if the suitability of these additions had been established following the k-value concept or equivalent performance concepts (equivalent concrete performance concept ECPC, equivalent performance of combinations concept EPCC).…”

Section: Introductionmentioning

confidence: 99%

Determining equivalent performance for frost durability of concrete containing different amounts of ground granulated blast furnace slag

Wawrzeńczyk

Juszczak

Molendowska

2016

Bulletin of the Polish Academy of Sciences Technical Sciences

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Abstract. This paper deals with the issues pertinent to the design of frost-resistant concretes in exposure class XF3 (high water saturation) when the concretes are made with cements containing ground granulated blast furnace slag (ggbs).The testing programme covered four series of non-air entrained concrete made with cements CEM I, CEM II/A-S, CEM II/B-S and CEM III/A containing 0%, 13%, 28% and 53% ggbs respectively, and two non-air entrained concrete series with the binder made from CEM I and 0 to 55% ggbs. The water-binder (w/b) ratio ranged from 0.25 to 0.55. Frost durability testing was performed using a modified ASTM C666A procedure to determine changes in mass (dm) and beam length (dL). The relationships occurring between the w/b ratio and ggbs content in the binder and the length change (dL) of the specimens were described using curvilinear regression functions, through the analysis of artificial neural networks.Slag-content-dependent critical values of the w/b ratio were determined taking the length change dL = 1.3 mm to be the criterion for the resistance to internal cracking. In the authors' view, this approach can be a good method for checking equivalent performance of concretes made with cements containing mineral additions.

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Behaviour of cement concrete at high temperature

Cited by 242 publications

References 19 publications

Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete

Effect of Elevated Temperature on Mechanical Properties of Limestone, Quartzite and Granite Concrete

Avaliação da resistência residual de lajes alveolares em concreto armado em uma edificação industrial após incêndio

Determining equivalent performance for frost durability of concrete containing different amounts of ground granulated blast furnace slag

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