Novel Lightweight Artificial Aggregate Production: 3D-Printed Aggregate in Lightweight Concrete

This study introduces a novel lightweight artificial aggregate manufactured using fused deposition modeling (FDM) 3D‑printing and evaluates its influence on the fresh, mechanical, physical, and durability performance of lightweight aggregate concrete (LWAC). Three aggregate geometries, spherical, edged, and irregular were fabricated from polylactic acid (PLA), and the optimal printing infill density was determined through a multi-criteria decision-making approach using TOPSIS, considering particle crushing strength (PCS), density, and production cost. The optimized 100% infill density configuration was subsequently employed in LWAC mixtures, in which 3D‑printed aggregates fully replaced natural pumice aggregate. The results demonstrate substantial performance improvements across all mixtures incorporating 3D-printed aggregates (3DPA). The 28-day compressive strength of concrete increased by 15-34% relative to pumice-based LWAC, while all mixtures achieved a density lower than 2000 kg/m3. The water absorption and open porosity decreased by up to 32% and 27%, respectively, owing to the impermeable polymeric shell of the 3DPA. Capillary sorptivity significantly reduced for spherical and edged geometries, while irregular shapes induced slightly higher sorptivity due to geometry-related ITZ heterogeneities. The abrasion resistance improved by as much as 23%, and chloride migration resistance exhibited remarkable enhancement, with spherical and edged aggregate concretes yielding “very low” Dnssm values (