Development of green 3D printable cementitious composites using multi-response optimisation method

3D printing is a new but one of the most sustainable and revolutionary manufacturing technologies for the construction sector. The printability relies on fresh properties; hence, effective mix design requires a systematic optimisation approach. This paper, for the first time, develops a green and 3D printable cementitious composite (3DP-CC) employing the Taguchi-based TOPSIS optimisation method, and a high volume of ground granulated blast furnace slag (GGBFS) is used, in replacement of cement, which has been commonly used in 3DP-CC. The developed optimisation material design method and 3D printing materials consider nine performance criteria encompassing fresh and mechanical properties and sustainability aspects, including flowability, buildability, mini-slump, deformation, weighted mini-slump, 1-day and 28-day compressive strength, flexural strength, and CO 2 emission rate. Three factors, each with three control levels, are analysed, including GGBFS content (50 %, 60 %, 70 %), superplasticiser (SP) dosage (4, 5, 6 L/m³ of mortar), and viscosity modifying agent (VMA) dosage (4, 8, 12 L/m³ of mortar). The mix, with 60 % GGBFS content, SP dosage and VMA dosage of 5 L/m³ and 8 L/m³ is determined to be the optimal mix via using the devised optimisation method, and the optimal mix design is validated by 3D printing, demonstrating favourable printability performance. • Optimized mix design developed for sustainable 3D printable cementitious composite. • High-volume GGBFS replacement (60 %) substantially reduces reliance on cement. • 3D printability validated via fresh, mechanical, and direct printing performance tests. • TOPSIS-based Taguchi method applied for the first time to optimize 3D printable mix design.