LIGHTWEIGHT CONCRETE FOR MODULAR CONSTRUCTION: STRENGTH, DENSITY AND MICROSTRUCTURAL PERFORMANCE AT LABORATORY AND PRODUCTION SCALES

Abstract

The performance of lightweight structural concrete with porous aggregates (LWPA) in precast and modular construction is strongly influenced by aggregate grading and curing conditions; however, the comparative effects of different expanded clay aggregate fractions under production-orientated conditions remain unstudied enough. This study evaluates the influence of 5–8 mm and 5–10 mm expanded clay aggregate fractions on the physical, mechanical, and microstructural properties of LWPA at both the laboratory and production scales. The density, compressive strength, and workability were measured. Following laboratory validation, full-scale wall panels and volumetric blocks were produced and tested under production conditions. Microstructural features were investigated using XRD, SEM, and EDS. The results showed that at 28 days, the concrete produced with the 5–10 mm expanded clay aggregate fraction exhibited a 12.3 to 12.8% higher compressive strength than mixes with the 5–8 mm fraction, depending on the mixture type. The density of the mixtures ranged from 1867 to 1912 kg/m³, meeting LWPA requirements. Microstructural analysis confirmed enhanced hydration and a denser cement matrix in the experimental mixtures. The findings demonstrate that optimized expanded clay aggregate grading provides an effective balance among strength, density, and technological performance, supporting the production of prefabricated wall panels and volumetric blocks for sustainable and modular construction.