Modelling of heated concrete

Khoury, G. A.; Majorana, C. E.; Pesavento, Francesco; Schrefler, Bernhard A.

doi:10.1680/macr.54.2.77.40895

Cited by 48 publications

(56 citation statements)

References 18 publications

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“…The integrity and load-bearing capacity of the structure may be imperilled. Furthermore, the explosive thermal spalling of concrete during fire occurs mostly without advance notice [9,10,18,24]. It should also be noted that the presence of loading during heating influences the strength of concrete since the failure mode is generally thermal spalling when concrete is exposed to high temperature [25].…”

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confidence: 99%

Retained properties of concrete exposed to high temperatures: Size effect

Arıöz

2009

Fire and Materials

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SUMMARYConcrete as a construction material is likely exposed to high temperatures during fire. The retained properties of concrete after such exposures are still of great importance in terms of the serviceability of structures. This paper presents the effects of high temperatures on the physical, mechanical, and microstructural properties of concrete. Specimens with different sizes were exposed to high temperatures ranging from 200 to 1200 • C. The compressive strength, splitting tensile strength, ultrasonic pulse velocity, and rebound numbers of the specimens were determined. The microstructures of the specimens were examined by scanning electron microscope (SEM) analyses. The test results indicated that the retained compressive strength of concrete considerably decreased with increase in temperature. The effect of specimen size on the retained compressive strength was not pronounced. The retained splitting tensile strength of concrete remarkably reduced as the temperature was increased. The specimen size played an important role on the retained splitting tensile strength of concrete up to 400 • C. The test results revealed that ultrasonic pulse velocity (UPV) test can be successfully used in order to check the uniformity of fire-damaged structures. The rebound numbers decreased with increase in exposure temperature. SEM studies on specimens exposed to 800 • C revealed significant changes in the microstructure of the concrete.

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confidence: 99%

Retained properties of concrete exposed to high temperatures: Size effect

Arıöz

2009

Fire and Materials

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“…Figure 3 provides a comparison of the models given in Table 1, the proposed relationship and the experimental results of Anderberg and Thelandersson (1976) and Khoury et al (2002). The elastic modulus of concrete typically loses 10-20% of its original elastic modulus when heated to 3008C and 70-80% at 8008C.…”

Section: Prestressed Elastic Modulus Of Concrete At Elevated Temperatmentioning

confidence: 96%

Prestressed concrete thermal behaviour

Aslani

2013

Magazine of Concrete Research

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The structural fire safety capacity of concrete is very complicated because concrete materials have considerable variations. Constitutive relationships for prestressed normal-strength concrete (NSC) and high-strength concrete (HSC) subjected to fire are needed to provide efficient modelling and to meet specific fire-performance criteria of the behaviour for prestressed concrete structures exposed to fire. In this paper, formulations for estimating the parameters affecting the behaviour of unconfined prestressed concrete at high temperatures are proposed. These formulations include residual compression strength, initial modulus of elasticity, peak strain, thermal strain, transient creep strain and the compressive stress-strain relationship at elevated temperatures. The proposed constitutive relationships are verified with available experimental data and existing models. The proposed relationships are general and rational, and show good agreement with the experimental data. More tests are needed to further verify and improve the proposed constitutive relationships.

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“…There is a contradiction in the literature about the nature and types of the decomposition products of C-S-H gel which decomposes over a wide range temperature (about from 105˚C to 1000˚C [29]) as a result of its amorphous nature. Zhang and Ye calculated the activation energy (Ea) of the dehydration of C-S-H and portlandite by Arrhenius equation from TGA/DTG results.…”

Section: ) Estimation Of the Dehydration Mechanisms And Kinetics Formentioning

confidence: 99%

Effect of High Temperatures on the Microstructure of Cement Paste

Tantawy¹

2017

MSCE

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The microstructural and compositional changes within the cement paste exposed to high temperatures were monitored by XRD, FTIR, TGA/DTA and SEM techniques to understand the nature of decomposition of C-S-H gel and the associated physicomechanical properties of thermally damaged cement paste. OPC paste (w/c ratio 0.27) was hydrated for 28 days then fired up to 750˚C for 2 hours (heating rate 10˚C/min). The relative mass percent of calcium hydrates and portlandite was estimated by calculations derived from TGA results. Beyond 450˚C, the percentage of portlandite sharply diminishes and C-S-H progressively decomposes into C 2 S and C 3 S until complete loss of calcium hydrates content occurs at 750˚C. An increase of the total porosity, severe loss in mechanical strength and propagation of harmful cracks occurs. The thermal shock as a result of cooling of the heated cement paste and the rehydration of lime enhance the propagation of harmful cracks.

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Modelling of heated concrete

Cited by 48 publications

References 18 publications

Retained properties of concrete exposed to high temperatures: Size effect

Retained properties of concrete exposed to high temperatures: Size effect

Prestressed concrete thermal behaviour

Effect of High Temperatures on the Microstructure of Cement Paste

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