Specimen geometry effects on lightweight self-compacting concrete made with recycled aggregates—research trend and knowledge gap analysis

This paper examines the effects of specimen size and shape on the performance of self-compacting lightweight recycled aggregate concrete (SCLWRAC). The study delves into the impact of different specimen geometries, such as cubes and cylinders, on the mechanical properties, particularly compressive strength, of SCLWRAC, with larger specimens demonstrating decreased strength, especially when higher recycled aggregate (RA) content is used. The paper also explores the components of self-compacting concrete, lightweight aggregates, and RAs, detailing how these materials interact based on their shape and size. Through scientometric analysis of publications from 2020 to 2026, this review identifies critical gaps in the research, particularly in standardized testing procedures, correction factors for geometry effects, and durability aspects such as chloride penetration and freeze–thaw resistance. The findings highlight the need for more consistent testing protocols, refined prediction models, and further exploration into the microstructural impacts of specimen geometry on the performance of SCLWRAC. Future research should aim to address these gaps to improve the practical application and sustainability of SCLWRAC in structural design.