Tensile basic creep of early-age concrete under constant load

Østergaard, Lennart; Lange, David A.; Altoubat, Salah; Stang, Henrik

doi:10.1016/s0008-8846(01)00691-3

Cited by 133 publications

(28 citation statements)

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“…The early-age behavior of cement-based materials has been experimentally studied for decades. Several signifi-Email address: thanh-tung.nguyen@uni.lu (Thanh-Tung Nguyen ) cant contributions in this area can be found, e.g., in [4], where the author developed a restrained shrinkage test methodology to characterize the early-age mechanical behaviors; Kolver et al [5] and Østergaard et al [6] studied the tensile creep of concrete at early-age; or another interesting work proposed by Lura et al [7] to investigate the effects of curing temperature and type of cement on the shrinkage properties. The phenomena of autogenous shrinkage induced cracking are considered in [8] for high-performance concrete, in [9] for slag cement concretes, and in [10][11][12][13] for fiber reinforced concrete.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical analysis of early age behavior in non-reinforced concrete

Nguyen

Weiler

Waldmann

2019

Construction and Building Materials

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An approach combining numerical simulations and experimental techniques is proposed to investigate the early-age properties of non-reinforced concrete. Both thermo-mechanical and fracture behaviors are studied, providing a deep insight into the hydration process. This work makes an important step in understanding the effects of hydration on the performance of cement-based materials. More specifically, in the first part, the shrinkage and fracture properties of a non-reinforced concrete have been experimentally considered, along with the characterization of several material parameters. The experimental results exhibit a high risk of early-age cracking for this kind of concrete. Especially, the fracture phenomena are complex, including multi-evolution-stages, initiation, propagation, stop-growing, and re-growing. In the second part, the computational modeling based on the phase field method of failure mechanism is applied to simulate the thermal, mechanical and fracture behavior due to early-age hydration. A detailed discussion on the identification of model/material parameters and the construction of numerical model including the boundary conditions is given. We provide the following comparison between predictions of the numerical simulation with the experimental observations. An excellent predictive capability of the computational model is noted. More importantly, this work demonstrates the performance of the proposed approach, which requires only a few tests to identify the model inputs. Most of the chemo-thermal parameters can be theoretically determined based on the concrete mix and the chemical/mineral compositions of the cement.

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Section: Introductionmentioning

confidence: 99%

Experimental and numerical analysis of early age behavior in non-reinforced concrete

Nguyen

Weiler

Waldmann

2019

Construction and Building Materials

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“…In other words, the time required to achieve a certain level of a desired property is perceived as the early age (Mehta and Monteiro, 2006). Table 1 summarises the early-age period as considered by different researchers (Altoubat, 2002;Bissonnette and Pigeon, 1995;Brooks and Megat-Johari, 2001;Holt, 2001;Holt and Leivo, 2004;Kahouadji et al, 1997;Khan, 1995;Kovler et al, 1999;Mehta and Monteiro, 2006;Nassif et al, 2003;Oluokun et al,1991a;Østergaard et al, 2001;Pane and Hansen, 2002;Rilem, 1981;Wongtanakitcharoen and Naaman, 2007). Generally, the early age is the first few hours or days after casting concrete that are characterised by two main processes: setting (progressive loss of fluidity) and hardening (gaining strength).…”

Section: Introductionmentioning

confidence: 99%

Early-age properties of concrete: overview of fundamental concepts and state-of-the-art research

Nehdi

Soliman

2011

Proceedings of the Institution of Civil Engineers - Constructio

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The long-term performance of concrete structures is affected to a large extent by the properties and behaviour of concrete at early age. However, the fundamental mechanisms affecting the early-age behaviour of concrete have not yet been fully understood. This is due to the various highly interrelated factors influencing it, and the complexity of testing techniques needed for its investigation. With modern developments in concrete technology, it has become essential to evaluate the influence of these interrelated factors and their implications for the service life of concrete structures. Thus, a more fundamental approach for investigating the early-age behaviour of concrete, along with more reliable testing techniques, is required. This paper provides a critical overview of research on the mechanisms that affect the properties of concrete and its performance at early age. It provides useful, concise and coherent information on the behaviour of concrete at early age, which should enhance the understanding of the implications of such behaviour on the service life performance of concrete structures. Notationreal compliance function k, n relation coefficients k d thermal diffusivity (m 2 /s) T a average concrete temperature during the time interval Dt T 0 datum temperature v(r)Poison's ratio at a degree of hydration r Dt time interval e autogenous (t, t9) autogenous shrinkage strain at time t e total (t, t9) total strain of a concrete specimen measured from the basic creep test at time t caused by an amount of constant stress applied at age t9 k thermal conductivity (W/(m.K)) r bulk density (kg/m 3 ) s total applied stress s c concrete strength

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“…Since Freyssinet highlighted the creep of concrete in France in 1912, regardless of Hatt's findings in the United States in 1907 [3], the phenomenon has been extensively studied, as shown by the numerous publications on this topic (see [4][5][6][7][8][9][10] for example).However, due to the difficulties of performing a tensile test on cement-based materials [11], particularly for fixing of the samples to the loading device [12] and measuring the values of the strains, which are too small for most extensometers to cope with, the majority of experimental studies on concrete creep have dealt with compressive creep. When experiments involve tensile creep of cement-based materials, the tests are usually limited to early age behavior [11,[13][14][15][16][17][18][19][20][21][22][23]. However, as the tests are performed a short time after casting, the coupling between creep and the effects of hydration (strength gain, shrinkage, etc.)…”

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confidence: 99%

Basic creep of concrete under compression, tension and bending

Ranaivomanana

Multon

Turatsinze

2013

Construction and Building Materials

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Investigations on concrete creep are often limited to the compression behavior due to the difficulty of performing tensile tests on cement-based materials. This paper describes the experimental setup developed to achieve direct tensile and bending concrete creep. The precautions taken to obtain relevant data are described. For comparison, tensile, flexural and compressive basic creep test were conducted in parallel. Although the approach is still controversial, the basic creep strain was determined by subtracting the shrinkage strain and instantaneous strain from the total strain. Results available for specimens subjected to 50% of the strength in tension or in compression are presented. The final discussion compares the basic creep under the different types of loading.Because of its poor strain capacity and low tensile strength, concrete is brittle and highly sensitive to cracking. In most cases, cracks can significantly reduce the lifetime of a structure by allowing the ingress of aggressive agents. Cracks have various origins, which are all associated with the existence of extensions: effect of external loading, physicochemical pathologies leading to the formation of new expansive products (Alkali-Aggregate Reaction -AAR, Delayed Ettringite Formation -DEF, corrosion). A non-uniform state of deformation associated with thermal or hydric gradients or restrained strain in bonded cement-based overlays induce built-in tensile stresses which can also initiate cracking. The heterogeneity of concrete also plays an important role in the mechanism of crack formation. Even if a specimen is tested in compression, the first damage that occurs at the paste-aggregate interface is the consequence of tensile stresses resulting from the differences between the two phase moduli (for paste and aggregate) and from the interfacial transition zone (ITZ) [1], which has limited mechanical performance. According to Liners [2], the application of a compressive preload on a specimen can generate damage in tension, resulting in a significant drop in the tensile strength of up to 50% depending on the level and the duration of loading application. Therefore, in order to predict the risk of cracking in concrete elements, it is important to focus on the mechanical properties of concrete in tension, and particularly on its delayed behavior, the effects of which (cracking or stress relaxation) are not yet well understood. Since Freyssinet highlighted the creep of concrete in France in 1912, regardless of Hatt's findings in the United States in 1907 [3], the phenomenon has been extensively studied, as shown by the numerous publications on this topic (see [4][5][6][7][8][9][10] for example).However, due to the difficulties of performing a tensile test on cement-based materials [11], particularly for fixing of the samples to the loading device [12] and measuring the values of the strains, which are too small for most extensometers to cope with, the majority of experimental studies on concrete creep have dealt with compressive creep. When experimen...

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Tensile basic creep of early-age concrete under constant load

Cited by 133 publications

References 4 publications

Experimental and numerical analysis of early age behavior in non-reinforced concrete

Experimental and numerical analysis of early age behavior in non-reinforced concrete

Early-age properties of concrete: overview of fundamental concepts and state-of-the-art research

Basic creep of concrete under compression, tension and bending

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