In a groundbreaking study published in the journal *Buildings* (translated to English), researchers from the Faculty of Civil and Environmental Engineering at the West Pomeranian University of Technology in Szczecin, Poland, have demonstrated the feasibility of using 100% fine recycled concrete aggregates (fRAs) and recycled concrete powder (RCP) in 3D-printed concrete structures. Led by Pawel Sikora, the research offers promising insights into the potential of recycled materials in the construction industry, with significant implications for sustainability and cost-efficiency.
The study, titled “Demonstration of 3D-Printed Concrete Containing Fine Recycled Concrete Aggregates (fCAs) and Recycled Concrete Powder (RCP): Rheology, Early-Age, Shrinkage, Mechanical, and Durability Performance,” explores the properties of cement-based composites incorporating fRAs and RCP. The findings reveal that mixes containing up to 100% fRA as a replacement for natural river sand not only enhance the buildability of the mix but also reduce shrinkage within the first 24 hours of hydration.
“An increase in fRA content enhances the buildability of the mix, as confirmed by green strength tests,” noted Sikora. This is a significant finding, as buildability is a critical factor in the success of 3D-printed concrete structures. However, the study also found that the open time of mixes containing fRA and RCP was shortened, which could impact the printing process.
Despite a reduction in compressive strength (up to 55%) when RCP and fRA were introduced, all mixes—including those with 100% fRA and 10% RCP—exhibited compressive strengths above 30 MPa. This demonstrates their potential suitability for use in the construction industry. “All mixes exhibited compressive strengths above 30 MPa, showing their potential for use in the construction industry,” Sikora explained.
The durability properties of mixes modified with fRA showed a statistically significant reduction in flexural strength after 25 and 50 freeze–thaw cycles. However, cast specimens did not exhibit any notable reduction in mechanical performance after freezing and thawing cycles, indicating that the mixes could be suitable for use in environments with freeze-thaw cycles.
The life cycle assessment (LCA) results further underscore the high potential for using fRA and RCP derived from concrete waste in the additive manufacturing industry. This could lead to significant reductions in the environmental impact of construction, as well as cost savings for the energy sector.
The research by Sikora and his team opens up new possibilities for the use of recycled materials in construction. As the demand for sustainable and cost-effective building materials continues to grow, this study provides a promising direction for future developments in the field. The findings could shape the future of construction, particularly in the energy sector, where the demand for sustainable and cost-effective building materials is high.
This study is a significant step forward in the quest for sustainable construction materials. As the construction industry continues to grapple with the challenges of sustainability and cost-efficiency, the findings of this study offer a promising solution. The use of recycled materials in 3D-printed concrete structures could not only reduce the environmental impact of construction but also lead to significant cost savings. This study is a testament to the power of innovation and the potential of recycled materials in shaping the future of construction.