Investigating lightweight recycled brick aggregate concrete incorporating EPS beads: Application to masonry units

Construction and demolition (C&D) waste, including burnt clay bricks and concrete, combined with nondegradable industrial waste such as expanded polystyrene (EPS), presents a significant global disposal challenge. Recycling C&D waste into concrete aggregates offers a sustainable solution, while incorporating EPS in lightweight concrete production supports eco-friendly construction. This study focuses on developing lightweight recycled brick aggregate concrete (LRBAC) using recycled brick aggregate (RBA) and EPS beads, specifically designed for partition walls in seismic structures, where reduced weight enhances structural performance. To minimize the carbon footprint, cement was partially replaced with fly ash at 33%, 50%, and 67%. Coconut fibers (15 mm length) were added to mitigate the reduction in mechanical properties caused by EPS and cement replacement. Used cooking oil (UCO) was employed as a sustainable alternative to commercial superplasticizers, and its impact on mechanical and durability properties was assessed. Key properties, including density, modulus of elasticity (MOE), compressive strength, and modulus of rupture (MOR), were evaluated in accordance with ASTM C129 standards for lightweight masonry units. Durability was assessed through water absorption tests and exposure to severe weathering, including cyclic ponding in 5% sulfuric acid and supersaturated brine solutions. The results show that despite that EPS beads addition and exposure to harsh weathering decreased the mechanical and durability properties, LRBAC specimens satisfied the ASTM C129 criteria for lightweight concrete masonry units. Moreover, LRBAC incorporating EPS and FA are less costly and have lower carbon footprint, highlighting the benefit of using C&D and industrial waste for production of sustainable lightweight concrete for masonry units.