Reusing recycled waste materials in buildings is gaining more and moreattention for what it offers economic, environmental, and energy benefits;and many researchers are nowadays working on producing new sustainableconstruction materials incorporating recycled wastes. In this scope, thiswork uses an experimental approach aiming at understanding the effect ofincorporating Expanded Polystyrene (EPS) beads in concrete and proposingthermally improved concrete mixtures for the production of hollow blocksin Lebanese constructions by substituting fine aggregates with recycledproducts such as EPS in order to promote their insulating properties. Threedifferent diameters of EPS beads (2 mm ~ 3 mm, 3 mm ~ 4 mm and 4 mm ~5 mm) are studied with different volumetric ratios (20%, 40%, 60% and80%) in order to investigate the effect of EPS on the thermal properties ofconcrete. The results showed that the only the percentage of incorporatedEPS beads impacted the thermal performance of the concrete mixtureswhile the EPS diameters have a negligible effect on the thermal propertiesof the concrete samples.