Abstract

Additive manufacturing has enabled the widespread adoption of 3D printable concrete (3DPC) mixtures in the

construction industry due to their significant advantages over conventional methods. Compared to traditional formwork

systems, 3DPC offers faster production times, reduced labor demands, improved workplace safety and enhanced design

flexibility. However, the absence of coarse aggregates and the high proportion of fine materials and binders in these

mixtures often result in inferior drying-shrinkage performance. Furthermore, the elevated binder content compromises

their sustainability and economic viability relative to traditional concrete. To address these limitations, recent studies have

explored the incorporation of fibers, pozzolanic materials, and industrial byproducts to enhance dimensional stability,

ecological balance, and cost efficiency. In this study, blast furnace slag (BFS) was used as a partial replacement for cement

at 0%, 25, 50 and 75% of the total binder volume to mitigate the environmental impact of 3DPC mixtures.

Additionally, straight steel fibers sourced from waste tires, with lengths of 5, 10 and 15 mm, were incorporated at volumetric

ratios of 0%, 0.5% and 1% to improve drying-shrinkage resistance. A total of 27 experimental mixtures, including a control

mix, were prepared with a constant water-to-binder ratio of 0.4 and a maximum aggregate particle size of 2 mm. The flow

performance of these mixtures was evaluated, revealing a pronounced influence of the BFS substitution rate on flowability.

It was determined that the water-reducing admixture requirement of the mixtures decreased with increasing blast furnace

slag utilization ratio.