Development and performance evaluation of resource-efficient expanded perlite composites for sustainable building and smart urban infrastructure

The development of innovative, resource-efficient construction materials is increasingly important for sustainable buildings and the evolving infrastructure needs of smart cities.Expanded perlite (EP) is a lightweight mineral aggregate with potential for non-load-bearing components, but its high porosity creates a strength–density trade-off. This study experimentally investigates the effects of EP particle size, matrix formulation, and low-temperature post-demoulding conditioning on ultra-lightweight cementitious composites. Eighteen formulations were produced using three EP particle-size series designated as S1 = 4.0 mm, S2 = 2.0 mm, and S3 = 0.8 mm, with six matrix formulations (a–f) in each series. Specimens were maintained for 28 days under ambient conditions (Ambient-conditioned) or conditioned for 7 days at 45 °C followed by 21 days under ambient conditions (45 °C-conditioned). Bulk density, compressive strength, peak load, water absorption, and displacement response were evaluated. The developed composites achieved densities ranging from 528 to752 kg/m³. Under ambient conditioning, formulation S3d containing 0.8 mm EP achieved the highest ambient-conditioned compressive strength of 1.904 MPa, with a density of 720 kg/m³ and peak load of 4.76 kN, whereas S3c and S2d provided the lowest-density alternatives. The 45 °C conditioning reduced density but generally decreased compressive strength and post-peak deformation. Strength–density efficiency identified S3d as the highest-efficiency formulation under ambient conditioning and S1d after 45 °C conditioning, indicating that no single formulation was optimal across all performance objectives. These findings demonstrate the critical influence of mineral aggregate particle size, cementitious mix design, and conditioning protocols on the mechanical performance of lightweight construction materials. The study establishes an experimental basis for developing resource-efficient, non-load-bearing building components, with potential applications in sustainable buildings and smart-city infrastructure. Further investigation of thermal performance, durability, and environmental impacts is required to validate their contribution to sustainable urban development.