Functional Lightweight Concrete Systems for Sustainable Load-Bearing Applications: Experimental Assessment of Perlite-Modified Reinforced Concrete Beams

The increasing demand for sustainable structural materials in the construction industry has intensified the need to develop high-performance and environmentally efficient reinforced concrete systems. In this context, the incorporation of functional material-enhanced concrete systems, including raw lightweight aggregates such as perlite, offers a promising pathway for reducing environmental impact while maintaining adequate structural performance. This study experimentally investigates the flexural behavior of reinforced concrete (RC) beams incorporating raw perlite aggregates within a functional material-enhanced structural framework. A total of four RC beams with identical geometry and reinforcement details were produced, including perlite aggregate beams (P25 and P40) and conventional aggregate beams (C25 and C40), corresponding to compressive strength classes of 25 MPa and 40 MPa. All specimens were tested under monotonic flexural loading conditions. The structural response was evaluated in terms of load–displacement behavior, stiffness degradation, ductility, energy dissipation capacity, moment–curvature response, and failure modes. The results indicate that perlite aggregate beams exhibit reduced stiffness and energy dissipation capacity compared to conventional counterparts at comparable mixture-average compressive-strength levels. However, the high-strength perlite beam (P40) demonstrated comparable flexural capacity and ductility to the normal-strength conventional beam (C25), highlighting its potential for sustainable structural applications. Furthermore, a building-scale environmental assessment based on a representative three-story reinforced concrete structure demonstrates that the use of raw perlite aggregates significantly reduces energy consumption, CO2-equivalent emissions, and water usage. From a functional materials perspective, the findings provide a basis for the future development of multifunctional load-bearing concrete systems, where lightweight aggregate substrates can be combined with protective or performance-enhancing coating technologies to achieve improved durability, environmental resistance, and structural efficiency. This integration could further enhance durability and long-term structural performance in load-bearing applications. © 2026 by the authors.