Expanded perlite and bio-based residues for circular low-carbon cementitious materials: a systematic review

The transition to circular and low-carbon construction requires materials that combine resource efficiency, thermal performance, mechanical adequacy, and waste valorization. This review synthesizes 139 studies published between 2010 and 2026 on expanded-perlite and bio-based cementitious materials, classified as bio-derived supplementary cementitious materials (SCMs) and ashes, bio-based lightweight aggregates, natural-fiber reinforcement, expanded-perlite aggregate, perlite powder/fines, and hybrid systems. It evaluates how constituent type, replacement level, particle characteristics, binder interactions, curing, moisture condition, density, and pore structure influence compressive strength, thermal conductivity, durability, and environmental performance. The evidence reveals a consistent strength–insulation trade-off: increasing porous lightweight constituents generally reduces density and thermal conductivity but may weaken matrix continuity, increase moisture sensitivity, and lower compressive strength. A selected perlite-powder mortar containing 15% replacement and 2% nanosilica reached 68.3 MPa, while selected bio-derived corn-stalk-ash mortar reached 50.15 MPa at 5% cement replacement. Lime–hemp composites reported thermal conductivity as low as 0.070 W/m·K. Across reviewed datasets, compressive strength generally increased with density, whereas thermal conductivity declined with increasing porosity. The synthesis indicates that no single formulation performs optimally across all criteria; instead, the most favorable systems seek to balance insulation, mechanical adequacy, moisture resistance, and carbon reduction through controlled substitution, particle grading, binder design, and curing. Environmental benefits were most evident when these materials displaced clinker or primary aggregates, while processing energy, transportation, service life, and end-of-life assumptions strongly affected carbon outcomes. Expanded perlite, bio-based residues, and hybrid formulations offer promising pathways for lightweight, thermally efficient, and low-carbon building-envelope applications.