Simulation of shrinkage induced cracking in cement composite overlays

A random lattice is used to model moisture transport in cement-based composites. Model geometry, and the scaling of the elemental diffusivity terms, are based on a Voronoi discretization of the material domain. Steady-state and transient potential flow problems are simulated, and compared with theory, to demonstrate model accuracy and objectivity with respect to lattice random geometry. A novel routine is described for computing moisture flux values at the random lattice sites. Stress production, and potential shrinkage crack development, are driven by the associated drying processes. The random lattice modeling of moisture movement is coupled with rigid-body-spring networks (RBSN), which account for elasticity, creep, and fracture properties of the material. The RBSN is based on the same Voronoi discretization of the material as used to model moisture movement. Relative humidity contours, stress contours, and crack plots are produced for a cement composite overlay restrained by a mature concrete substrate. That example is based on a set of simulation results reported in the literature. (C) 2003 Elsevier Ltd. All rights reserved.