The effect of expanded polystyrene synthetic particles on the fracture parameters, brittleness and mechanical properties of concrete

•Results showed with increase of EPS volume the fracture toughness decreases.•Size effect curve showed concrete brittleness increases with increase of EPS volume.•The effect of EPS volume on mechanical properties was studied. Expanded polystyrene (EPS) concrete is known as a lightweight and environmentally-friendly material with suitable properties for energy absorption which is made by partial or full replacement of the natural stone materials with man-made non-absorbent grains. In recent years, depending on the concrete density and strength requirements, EPS concrete is used extensively in different structural elements. In this study, the mechanical properties and fracture parameters of lightweight EPS concrete with different EPS volume percentages (0%, 10%, 20%, 30%, and 40%) and two water-to-cement ratios (0.4 and 0.5) are evaluated. The results of the experiments showed that the apparent density, tensile strength, compressive strength, elasticity modulus and ultrasonic waves velocity of EPS concrete decrease when the volume fraction of EPS increases. Furthermore, the results of the fracture tests showed that with increase of the volume fraction of EPS aggregates from 0% to 40%, (a) the fracture toughness reduces, (b) the reference length, a∞∗,in BEM method as a ductility index which is explained by the change in the fracture dimension increases, (c) the behavior of the specimens approaches strength criterion based on the size effect plot. Finally, based on the experimental results, new empirical models are proposed for the prediction of mechanical properties and fracture toughness of EPS concrete as a function of apparent density of plain concrete.