Effect of copper slag as fine aggregate on the fresh properties of 3D printable concrete.

This research explores the potential of using copper slag as a substitute for river sand in 3D printable concrete (3DPC), aiming to enhance sustainability in construction. The research evaluates three different concrete mixes: a reference mix with river sand (RS-BM) and two mixes with full replacement of copper slag by volume (CS-VR) and by weight (CS-WR). The key aspects analyzed include fresh properties such as rheology, flowability, extrudability, open time, and buildability. The results show that CS-VR mixes maintain desirable flow and slump characteristics, with consistent printability and stability similar to those of RS-BM. The CS-VR exhibited the longest open time and superior buildability, with minimal shape deformation. The rheological analyses reveal that the Modified Bingham model best represents the dynamic yield stress (DYS) for the mixes. The CS-WR consistently shows the highest DYS values, indicating robust printability and structural integrity. The viscosity analysis across shear rates illustrates shear-thinning behavior in all mixes, with RS-BM exhibiting higher initial viscosity compared to CS-VR and CS-WR. This study concludes that copper slag-based mixes (CS-VR and CS-WR) offer potential benefits over 3D printable river sand mixes in terms of material performance and environmental impact.