Sustainable 3D Printable Concrete-Mix Using Copper-Slag (2025-01)¶

This study investigates the feasibility of fully replacing conventional river sand (RS) with copper slag (CS) as fine aggregate in a 3D Printable Concrete (3DPC) mix, emphasizing sustainable construction practices. The performance of 3DPC mixes with copper slag was evaluated through comprehensive rheological and mechanical assessments, including flowability, extrudability, buildability, open time, shape retention, compressive strength, and non-destructive testing for both cast and printed specimens. Results indicate that the CS mix achieves superior buildability, with a static yield stress of 2309.9 Pa compared to 1594.1 Pa for the RS mix. While the dynamic yield stress of the CS mix is 60% higher than that of the RS mix, it exhibits enhanced flowability due to its higher density, reducing the demand for superplasticizers. The CS mix also demonstrates prolonged flowability, smoother filament appearance, and superior mechanical performance, with compressive strength increases of 17%, 26%, and 37% in the X, Y, and Z directions, respectively, compared to the RS mix. The study underscores the potential of copper slag as a sustainable and effective replacement for river sand in 3D concrete printing, achieving enhanced structural performance and sustainability.