Micromechanical Modeling of Concrete Creep at Early Age
Lev Khazanovich
Department of Civil Engineering, University of Minnesota
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Abstract
Characterization of early age behavior of concrete is an important factor in modeling of long-term behavior of concrete pavements. The presentation deals with three-dimensional micromechanical modeling of concrete creep at early age. In this formulation, concrete is treated as a two-phase composite material consisting of an aging matrix (cement paste) and elastic inclusions (aggregates). The aging matrix uniaxial creep behavior is described by Bazant’s solidification theory, which models aging by volume growth of non-aging viscoelastic products of cement hydration. The bulk modulus of the matrix is assumed to be time-independent.
Time-translation non-invariant behavior of the aging matrix complicates determination of effective properties of the composite material. To overcome this challenge, continuous integral operators are approximated by operators acting in finite-dimensional spaces. A transformation converting the viscoelastic boundary value problem (BVP) to a series of independent elastic BVPs is introduced. This along with the Mori-Tanaka scheme was adapted for determining the effective shear and bulk creep operators of the composite material, resulting in rational functions of operators.