Compressive behavior of an idealized EPS lightweight concrete: size effects and failure mode K. Miled a ,R.LeRoy b ,K.Sab a, * , C. Boulay b a LAMI (ENPC/LCPC, Institut Navier), 6 et 8, Avenue Blaise Pascal, Cit e Descartes, Champs-sur-Marne, 77455 Marne-la-Vall ee, France b Laboratoire Centrale des Ponts et Chauss ees, BCC, 58, BD Lefebvre, 75732 Paris cedex 15, France Received 25 February 2003; received in revised form 29 July 2003 Abstract The purpose of this paper is to study size effects and failure mechanism of an idealized lightweight expanded polystyrene (EPS) concrete under compression. Two types of idealized 2D-EPS concrete specimens were obtained by perforating prismatic mortar sheets according to two periodic holes patterns with two diameter sizes. Then, specimens were subjected to standard uniaxial compressive tests. Results show that similar compressive strengths for the two specimens are obtained. Moreover, a specimens tensile failure mode with no cracks localization has been observed, which allows us to conclude that there is no size effect engendered by the quasibrittle behavior of the considered idealized EPS lightweight concrete. To simulate and predict numerically the absence of size effect on the compressive strength, periodic non-linear homogenization finite element calculations, with non-local Mazars damage model, were firstcarriedoutonunitcellsofincreasingsizetodeterminethenumberofunitcellstoformtherepresentativevolume element (RVE) of the considered idealized EPS lightweight concrete structures. Finally, uniaxial compressive tests on the two specimens have been simulated and non-local Mazars model parameters have been fitted to reproduce in a satisfactory manner similar compressive strengths for the two specimens, matching those obtained experimentally. Ó 2003 Elsevier Ltd. All rights reserved. Keywords: EPS lightweight concrete; Periodic microstructure; Compressive behavior; Failure mode; Size effect; Damage localization 1. Introduction The demand for lightweight concrete in many applications of modern construction is increasing, owing to the advantage that lower density results in a significant benefit in terms of creating much more elegant and economical structures. Light- weight aggregates are broadly classified into two types: natural (pumice, diatomite, volcanic cin- ders, etc.) and artificial (perlite, clay, sintered fly ash, expanded shale, etc.). Expanded polystyrene (EPS) beads of very smooth and rounded shape are a type of artificial ultra-lightweight aggregate (density of less than 30 kg/m 3 ). They can be in- corporated in mortar or cement paste to produce low density concretes required for building appli- cations like cladding panels and load-bearing concrete blocks. Also, they can be used as a * Correspondingauthor.Tel.:+33-164-153749;fax:+33-164- 153741. E-mail addresses: miled@lami.enpc.fr (K. Miled), leroy@ lcpc.fr(R.LeRoy),sab@lami.enpc.fr(K.Sab),boulay@lcpc.fr (C. Boulay). 0167-6636/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.mechmat.2003.08.004 Mechanics of Materials 36 (2004) 1031–1046 www.elsevier.com/locate/mechmat