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Creep of concrete: re-conciliation of rheological chain models and recent micromechanics approaches

Concrete creep is often described by rheological chain models, i.e. Maxwell or Kelvin-Voigt chains. The parameters involved in the later are normally back-computed from fitting creep tests. On the other hand, micromechanics models aim at relating the macroscopic creep properties to the intrinsic properties of hydrates. The present contribution wishes to reconcile this seemingly distant worlds, based on recently discovered formal analogies between the chain models on the one hand, and micromechanical models on the other: These analogies concern shear stresses and strains acting on the rheological models, and those acting on a micromechanical representative volume element consisting of an elastic solid matrix with embedded viscous interfaces, whereby the respective viscosity arises from layered polar fluids absorbed at these interfaces. The Kelvin-Voigt parameters appear as being much simpler and more intuitively related to the micromechanical quantities, when compared to the Maxwell parameters. More specifically, rheological spring parameters are always related to the shear stiffness of the elastic solid matrix, while they may additionally depend on the Poisson’s ratio of the elastic solid matrix, and on the interface density. On the other hand, dashpot viscosities are always related to interface viscosities, interface radii, and interface densities; and they may even depend on the Poisson’s ratio of the elastic solid matrix.

Author(s):

Mehran Shahidi    
Vienna University of Technology, Austria; Christian Doppler Laboratory, University of Natural Resources and Life Sciences Vienna, Austria
Austria

Roman Wendner    
Christian Doppler Laboratory, University of Natural Resources and Life Sciences Vienna, Austria
Austria

Bernhard Pichler    
Vienna University of Technology, Austria
Austria

Christian Hellmich    
Vienna University of Technology, Austria
Austria