In the quest to reduce the construction industry’s carbon footprint, researchers have turned to an unlikely ally: waste from the welding process. A recent study published in *Construction Materials* (translated as *Building Materials*) explores the potential of using submerged arc welding (SAW) slag as a precursor for low-carbon geopolymeric materials, particularly in 3D printing applications. The research, led by Fernando Fernández from the Department of Sustainable Construction at the Centro Tecnológico de la Construcción (CTCON) in Murcia, Spain, offers promising insights into sustainable construction materials.
Geopolymers, known for their low carbon footprint, are gaining traction in the construction industry. However, their production often relies on materials like fly ash or blast furnace slag, which are not always readily available or sustainable. Fernández and his team investigated the use of SAW slag, a byproduct of the welding process, as a partial replacement for ground granulated blast furnace slag (GGBFS) in geopolymer production.
The study found that increasing the molarity of potassium hydroxide (KOH) used in the geopolymer mixture delayed setting times, with the longest delays observed at 10 M and 12 M. However, the highest compressive strength—48.5 MPa at 28 days—was achieved at 8 M. Higher molarities led to strength losses due to excessive precursor dissolution and increased porosity.
Fernández explained, “The optimal balance between setting time and compressive strength is crucial for the practical application of these materials. Our findings suggest that an 8 M KOH solution provides the best compromise.”
The research also revealed that replacing GGBFS with SAW slag increased setting times due to the higher Al₂O₃ and MgO content in GGBFS, which slowed down the geopolymerization process. The optimized formulation, containing 20% SAW slag and activated with 8 M KOH at a water-to-binder ratio of 0.29, exhibited good workability, extrudability, and shape retention. This mixture performed best in 3D printing trials, demonstrating strong layer adhesion and no segregation, although minor edge irregularities were observed.
Fernández highlighted the commercial potential of this research: “By utilizing SAW slag, we can reduce the reliance on traditional precursors and contribute to a more sustainable construction industry. This is particularly relevant for the energy sector, where the demand for sustainable and durable construction materials is growing.”
The study suggests that SAW slag is a promising sustainable material for 3D-printed geopolymers. Further optimization of printing parameters is needed to enhance surface quality, but the findings open new avenues for sustainable construction practices. As the construction industry continues to seek eco-friendly solutions, this research could pave the way for innovative applications of industrial byproducts in building materials.
Fernández’s work, published in *Construction Materials*, underscores the importance of interdisciplinary research in driving sustainable innovation. By leveraging waste materials and advanced manufacturing techniques, the construction industry can move towards a more sustainable and resilient future.