Downscaling Based Identification of Nonaging Power-Law Creep of Cement Hydrates

Königsberger, Markus; Hassan, Muhammad; Pichler, Bernhard; Hellmich, Christian

doi:10.1061/(asce)em.1943-7889.0001169

Cited by 55 publications

(42 citation statements)

References 48 publications

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“…This may further explain why the identified parameters do not follow a monotonic trend. Königsberger and colleagues proposed a model which would give the parameters we use based on the cement composition [61]. Previous work by this same author suggest a method to further predict strength [62,63].…”

Section: Model Validationmentioning

confidence: 99%

Microstructural effects in the simulation of creep of concrete

Giorla

Dunant

2018

Cement and Concrete Research

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The influence of the microstructure on the visco-elastic properties of concrete is investigated using finite element simulations at the meso-scale. We first derive a constitutive law for the creep of the cement paste which accounts for both recoverable and permanent deformations, as well as the influence of temperature and internal relative humidity. The model is calibrated on a set of experiments at the cement paste scale, and then validated after upscaling to the concrete scale. The model is then applied to study the influence of the microstructure on the macroscopic creep of concrete. We show that materials with finer particles exhibit less creep, and that the anisotropy of creep can be explained with the shape and orientation of the aggregates. Furthermore, the acceleration of the stress relaxation in the presence of damage is explained by the micro-mechanical interaction between the aggregates, the cement paste, and the micro-cracks.

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Section: Model Validationmentioning

confidence: 99%

Microstructural effects in the simulation of creep of concrete

Giorla

Dunant

2018

Cement and Concrete Research

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“…As for a cylindrical hydrate inclusion oriented in the e 3 direction, the nonzero components of the LC transformed Hill tensors read as [33] …”

Section: Abbreviationsmentioning

confidence: 99%

“…In the third step, the solution, i.e., the homogenized viscoelastic behavior, is back-transformed from the LC space to the time domain. Transformation of the viscoelastic phase properties of the hydrates, given in Equation (5), and of the polymers, given in Equation (7), according to the transformation rule (8), and consideration of the relation (10) yield LC relaxation tensor functions reading as [33]:…”

Section: Homogenization Of the Viscoelastic Properties Of Polymer-modmentioning

confidence: 99%

“…[8,9] The creep tensor functions of hydrates and polymers are introduced as follows. Königsberger et al [33] performed a top-down analysis of more than 500 ultra-short early-age creep tests on conventional cement pastes, with different compositions in terms of different water-to-cement ratios. Very remarkably, the large macroscopic database could be explained based on one universal isochoric creep tensor function of the microscopic hydrates, reading as:…”

Section: Viscoelastic Phase Propertiesmentioning

confidence: 99%

“…In Equation (5), t ref = 1 d = 86,400 s is the reference time; k hyd and µ hyd denote the universal bulk and shear modulus of the hydrates (see Table 1); and µ c,hyd and β hyd are the universal shear creep modulus and the power-law creep exponent of the hydrates, amounting to [33]:…”

Section: Viscoelastic Phase Propertiesmentioning

confidence: 99%

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Viscoelastic Behavior of Polymer-Modified Cement Pastes: Insight from Downscaling Short-Term Macroscopic Creep Tests by Means of Multiscale Modeling

et al. 2018

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Adding polymers to cementitious materials improves their workability and impermeability, but also increases their creep activity. In the present paper, the creep behavior of polymer-modified cement pastes is analyzed based on macroscopic creep tests and a multiscale model. The continuum micromechanics model allows for "downscaling" the results of macroscopic hourly-repeated ultra-short creep experiments to the viscoelastic behavior of micron-sized hydration products and polymer particles. This way, the increased creep activity of polymer-modified cement pastes is traced back to an isochoric power-law-type creep behavior of the polymers. The shear creep modulus of the polymers is found (i) to be two orders of magnitude smaller than that of the hydrates and (ii) to increase considerably with increasing material age. The latter result suggests that the creep activity of the polymers decreases with the self-desiccation-related decrease of the relative humidity inside the air-filled pores of cement paste. Furthermore, its decrease is most likely related to the penetration of cementitious hydrates into compliant polymer agglomerates.

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150 years reliable railway tunnels – Extending the hybrid method for the long‐term safety assessment

Hellmich

Pichler

Heissenberger³

et al. 2020

Geomechanics and Tunnelling

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Quantification of the level of loading of shotcrete supports from measured displacements of NATM‐driven tunnels is common practice in Austria. At construction sites of the Austrian Federal Railways (OeBB), a hybrid method developed at the TU Wien (Vienna University of Technology) has been successfully applied over the last 15 years. Because OeBB tunnels are designed for a lifetime of 150 years, the long‐term reliability of the support structures is of paramount interest. This provides the motivation for the development of hybrid methods applicable during the entire service life of tunnels, including also inner linings and segmental linings. The required extensions are intended to be carried out within a research program. The paper describes the state‐of‐the‐art and projected future developments.

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Downscaling Based Identification of Nonaging Power-Law Creep of Cement Hydrates

Cited by 55 publications

References 48 publications

Microstructural effects in the simulation of creep of concrete

Microstructural effects in the simulation of creep of concrete

Viscoelastic Behavior of Polymer-Modified Cement Pastes: Insight from Downscaling Short-Term Macroscopic Creep Tests by Means of Multiscale Modeling

150 years reliable railway tunnels – Extending the hybrid method for the long‐term safety assessment

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