Concrete creep at variable humidity: constitutive law and mechanism

Bažant, Zdeněk P.; Chern, J. C.

doi:10.1007/bf02473360

Cited by 190 publications

(97 citation statements)

References 36 publications

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“…The increase in creep with decreasing RH is due to the additional strain caused by simultaneous drying and loading. This excess deformation referred to as drying-induced creep (or simply drying creep) was first reported by Pickett [10] when the deformation of a specimen subjected to simultaneous drying and sustained loading was observed to be greater than the sum of the drying shrinkage from a similar specimen with no loading and the creep deformation of another similar specimen which does not dry (sealed specimen) but is loaded. It therefore appears that drying creep is still linked with load-induced shrinkage caused by microcracking effect and the drying gradient developed by the nonuniformity of shrinkage within the concrete specimen thereby subjecting the surface layer to tension which leads to further microcracking (tensile cracking).…”

Section: Basic and Drying Creepmentioning

confidence: 67%

“…It was therefore proposed that microcrack initiation is the origin of basic creep [4,9]. As the puzzle behind the actual mechanism of tensile and compressive creep of concrete is still unresolved, it is, however, generally accepted that they take place in the hydrated cement paste and are caused by the movement of absorbed water within and between the capillary pores and the cement gel pores in the microstructure of concrete [2,6,7,10]. There is currently limited literature comparing experimental tensile and compressive creep data for the same test conditions and the few available are not consistent in their findings [3].…”

Section: Introductionmentioning

confidence: 99%

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Influence of relative humidity on tensile and compressive creep of concrete amended with ground granulated blast-furnace slag

Ambrose

Forth

2018

Nig. J. Tech.

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This paper presents an experimental study on the influence of ambient relative humidity on tensile creep of plain concrete amended with Ground Granulated Blast-furnace Slag and compares it with its influence on compressive creep. Tensile and compressive creep tests were carried out on concrete specimens of 34.49MPa compressive strength and 0.56 water/binder ratio at 51, 68 and 100% relative humidity. The results show a linear relationship between compressive creep and relative humidity; this cannot be said about tensile creep. Tensile creep was observed to be more sensitive to change in ambient humidity than compressive creep. Based on equal applied stress, tensile creep was found to be several times higher than compressive creep and the difference was greater in drying creep than in basic creep. On the basis of equal stress/strength ratio, tensile-to-compressive creep ratio was slightly less than 1 for drying creep and much less for basic creep.

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Section: Basic and Drying Creepmentioning

confidence: 67%

Section: Introductionmentioning

confidence: 99%

Influence of relative humidity on tensile and compressive creep of concrete amended with ground granulated blast-furnace slag

Ambrose

Forth

2018

Nig. J. Tech.

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“…The most used model is probably the stress-induced shrinkage one, proposed by Bažant and Chern [15], which is based on experimental observations. It has been used in this study:…”

Section: Drying Creepmentioning

confidence: 99%

Modelling desiccation shrinkage of large structures

Benboudjema

Torrenti²

2013

EPJ Web of Conferences

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Abstract. Drying of cement-based materials induces drying shrinkage, which may cause prestress loss or/and cracking if strains are (self or externally) restrained. Drying shrinkage is difficult to predict, since it depends on the material mix, mechanical and hygral boundary conditions, geometry ... This paper focuses on the study of size effect on final drying shrinkage, which is not well documented in the literature. In the Eurocode 2 (European code model), a reduction factor is applied for large structure, which is in agreement with experimental data of one campaign (found in the literature). Using numerical simulations, it is shown that a large panel of models, including phenomenological models as physical ones (which takes into account of (aging) creep under capillary pressure (assumed to be the physical mechanism for drying shrinkage)), do not predict size effect on final value of drying shrinkage.

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“…1-The BAZANT model [16], based on the work of Bazant and Chern [19,20] which simulates the creep due to changes of humidity of the material; 2-The GRANGER model, based on the work of Granger [8], that allows adjustment of the evolution of the creep law for uniaxial loading and variable conditions of temperature and humidity; 3-The UMLV model [18], based on the work of Benboudjema [4], developed for simulating creep under biaxial loading and variable conditions of temperature and humidity. The choice of the creep model best suited to the structure is decided after consulting experts, and is based on the characteristics of the studied structures and materials.…”

Section: Epj Web Of Conferencesmentioning

confidence: 99%

Prediction of prestressing losses for long term operation of nuclear reactor buildings

Cornish-Bowden¹,

Thillard²,

Capra³

2011

EPJ Web of Conferences

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Abstract. Prestressed concrete is used in nuclear reactor buildings to guarantee containment and structural integrity in case of an accident. Monitoring and operating experience over 40 years has shown that prestressing losses can be much greater than the design estimation based on the usual standard laws. A method was developed to determine the realistic residual prestress level in structures, in particular for those where no embedded instrumentation was installed, taking into account in situ measurement results rather than design characteristics. The results can enable the owner to justify extending the lifespan while guaranteeing adequate safety and to define and plan adequate maintenance actions.

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Concrete creep at variable humidity: constitutive law and mechanism

Cited by 190 publications

References 36 publications

Influence of relative humidity on tensile and compressive creep of concrete amended with ground granulated blast-furnace slag

Influence of relative humidity on tensile and compressive creep of concrete amended with ground granulated blast-furnace slag

Modelling desiccation shrinkage of large structures

Prediction of prestressing losses for long term operation of nuclear reactor buildings

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