Mesoscale finite element modeling of EPS bead size effect on the strength and failure of lightweight concrete

Abstract

The mechanical performance of EPS concrete is strongly influenced by bead content and size, with smaller beads generally enhancing strength. This study develops a continuum mechanics framework that explicitly incorporates mortar, aggregates, and EPS beads. The mortar is modeled using a plastic-damage law, enhanced with a new compressive damage–strain relation and a strain-shifting procedure to reduce mesh sensitivity, while EPS beads are represented by an isotropic crushable foam model calibrated from experiments. A comprehensive set of meso-scale finite element analyses was conducted under both uniaxial compression and three-point bending, enabling prediction of compressive strength and modulus of rupture. The framework reproduces experimental strength–size dependencies, elucidates porosity-driven damage initiation and evolution, and introduces a new mathematical relation linking compressive strength with EPS volume ratio.