Study on the influence of EPS particles on the multi-dimensional properties of recycled lightweight aggregate concrete

Against the backdrop of the global surge in solid waste, severe electromagnetic pollution, growing demand for energy conservation, and the "dual carbon goals" (carbon peaking and carbon neutrality), fully exploring the functional utilization of construction and demolition waste (CDW) has become a current research focus. To this end, this study prepared recycled lightweight aggregate concrete using recycled concrete powder (RCP, replacing 20 % by weight of cement), three types of recycled expanded polystyrene (EPS) particles with different sizes and dosages (diameters: 0.5–1 mm, 1–2 mm, and 2–4 mm; dosages: 15–45 vol%), and 9 % nano-ferric tetroxide (Nano-Fe₃O 4 ) as raw materials. With reference to relevant national standards, indicators including its dry bulk density, mechanical properties, electromagnetic wave absorption performance, and durability were tested, and the influence of EPS particles on the properties of concrete and its mechanism was explored. The results show that the addition of EPS particles reduces the water absorption rate, apparent porosity, and dry bulk density of concrete, while improving its electromagnetic wave absorption and thermal insulation performance. Although the drying shrinkage, mechanical properties, and frost resistance decrease, they still meet the strength requirements for components. Specifically, when the dosage of EPS particles with a diameter of 2–4 mm is 30 % by volume, the sample exhibits the optimal comprehensive performance: it possesses good mechanical properties (41.28 MPa), excellent electromagnetic wave absorption performance (minimum reflection loss RL = −33.66 dB, effective bandwidth of 10.17 GHz), and superior thermal insulation performance (thermal conductivity of 0.1144 W/(m·K)). The recycled lightweight aggregate concrete prepared in this study features a high proportion of solid waste utilization, excellent electromagnetic wave absorption, and thermal insulation performance. It can provide a reference for the resource utilization and functional development of construction and demolition waste. • Systematically studied how EPS particle size and content affect the workability and physical properties of lightweight aggregate concrete. • Revealed the mechanism of EPS particle characteristics on the mechanical properties and durability of lightweight aggregate concrete. • Clarified the link between EPS parameters, thermal conductivity and wave absorption performance of the composites. • Provided a reliable theoretical basis for component design and performance optimization of high-performance EPS lightweight aggregate concrete.