Uncertainty quantification of the mechanical properties of lightweight concrete using micromechanical modelling

Abstract

This paper presents a micromechanical modelling framework for analysing the effects of microstructural uncertainties on the mechanical properties of heterogeneous materials. Specialised to lightweight concrete, the proposed framework addresses numerous microstructural uncertainties including the random size, spatial distribution and volume fraction of lightweight expanded polystyrene (EPS) inclusions, as well as the variation of cement matrix properties. A ”taking-placing” algorithm was used to realistically generate three-dimensional, heterogeneous microstructures of EPS concrete with EPS particles embedded into the cement matrix. The nonlinear behaviour of the cement matrix and EPS particles were taken into account by damage and plasticity material laws. By modelling the size, volume fraction and spatial distribution of EPS particles, as well as the properties of the cement matrix as stochastic parameters, the developed model can quantify the inherent uncertainty of EPS concrete. Extensive Monte Carlo simulations for more than 900 EPS concrete samples were performed for uncertainty quantification using finite element modelling. Enabled by a developed automated workflow, the proposed method can simultaneously perform a large number of computational steps on a single platform. A good agreement between the numerical and experimental results was obtained. The significance of each microstructural uncertainty on the mechanical behaviour of EPS concrete was examined in detail. In addition, the effect of particle size on EPS concrete was investigated. While this study focuses on the uncertainty quantification of EPS concrete, the proposed method can be applicable to a wide range of heterogeneous materials.