Experimental and microstructural study of the compressive strength of concrete samples containing low volumes of expanded polystyrene beads

The partial replacement of aggregates with expanded polystyrene (EPS) beads is a common technique to produce lightweight concretes. Much research have been already conducted on the compressive strength of EPS concretes containing high volumes of EPS beads. In the current study, however, specimens with low EPS volume contents are also examined. The results show that all the strength versus EPS volume content graphs initiate with a nearly plateau region. The length of this plateau region is found to be an increasing function of W/C ratio. It is also observed that the replacement of redundant water with the EPS beads initially improves strength but the trend is reversed beyond a critical volume content. Finally, the new empirical findings are interpreted and justified based on the underlying microstructural failure mechanisms. The results of this study can lay fresh grounds for the development of more realistic micromechanical and numerical models for EPS concrete.