Continuum microviscoelasticity of cementitious materials: Upscaling technique and first experimental validation

Abstract

We here propose a microviscoelasticity model for upscaling of the viscoelastic behavior of cementitious materials by means of a two-step homogenization scheme. Thanks to the correspondence principle, Laplace-Carson transforms of viscoelastic material properties (bulk and shear relaxation moduli) can be homogenized in the same way as purely elastic material properties. By means of numerical inversion of the Laplace-Carson-transformed (homogenized) relaxation moduli, we obtain time-dependent relaxation moduli of cementitious materials, as function of the viscoelastic properties of hydrates, of the elastic properties of cement, of water, and of aggregates, and of the (aging-dependent) volume fractions of these material phases within the composite material. From these macroscopic (homogenized) relaxation moduli we derive macroscopic creep functions of cementitious materials. The latter are compared to creep tests available in the open literature, as to validate the micromechanical material model. © CIMNE, 2007.