As 3D printing concrete (3DPC) technology continues to advance for automation in the construction industry, the need for environmentally friendly construction materials that reduce carbon emissions is becoming increasingly critical. Ordinary Portland cement (OPC), widely used in traditional construction, is known for its high carbon footprint due to the large amount of CO₂ emitted during its production. To address this issue, our research group is developing a slag-based 3D printable concrete that completely excludes the use of OPC, with the goal of realizing a sustainable, low-carbon construction technology.

Unlike conventional alkali-activated slag (geopolymer) systems, this research focuses on activating slag using calcium oxide (CaO), enabling the material to harden at ambient temperature without the need for high-temperature curing. This approach aims to produce a binder system that ensures both solidification and early strength development under mild conditions. To evaluate the material’s suitability for 3D printing, we are conducting a series of experimental analyses, including rheometer tests to measure time-dependent viscosity and yield stress, direct shear tests to assess interlayer bonding strength, and green strength tests to evaluate the structural stability of freshly printed layers. Through these investigations, we aim to develop a slag-based 3D printable material that meets the requirements for both buildability and structural integrity, contributing to the advancement of eco-friendly and functionally robust 3D printing construction technologies.