## 2 Materials and Methods
### Applied PLA Materials (Filaments)  
First of all, the authors should mention that the applied and considered materials were chosen for the following reasons:  
* ABS was chosen as a benchmark material due to its widespread use in 3D printing for engineering, high impact resistance, stiffness, and recyclability;
* PLA was investigated as a dynamic and eco-friendly alternative to ABS, with superior printability and lower environmental impact;
* ABS, despite its ordinary use, presents challenges in 3D printing, while PLA composites have shown significant advancements in recent years;
* The inclusion of both ABS and PLA allows for a comparative analysis of their properties, environmental impact, and printing requirements;
* The study emphasizes sustainability and material optimization, aligning with the goal of advancing eco-friendly construction methods;* While PLA offers environmental benefits, its limitations in specific applications are acknowledged, highlighting the need for balanced material selection in 3D-printed concrete reinforcement. During the tests, five different types of PLA material were used. High-impact PLA provides a higher impact resistance to the structure than PETG (polyethylene terephthalate glycol) materials and has a similar flexibility to polypropylene (PP). Engineering PLA was selected because the heat resistance of printed objects is exceptionally high, withstanding temperatures of up to 120 \({}^{\circ}\)C, which can be achieved without the need for post-heat treatment. This makes it much more resistant to external influences than other PLA materials. It also has high tensile and compressive strength and extremely high stiffness. The next material to be selected was electrical ESD (electrostatic discharge) PLA, which is a fiber-printed object that does not charge electrostatically due to special carbon and chemical additives. In addition, dust and fine dirt do not adhere to the surface of the objects. It provides a surface resistivity of the order of megaohms, but this depends mainly on the size and shape of the printed object. Furthermore, if printed at a higher temperature, it will provide a lower surface resistance. The surface resistance also depends on the print orientation, with a higher value in the \(Z\) direction and a lower value in the \(XY\) direction. The following material is slightly different from the other ones. While other materials are generally used in the automotive and electronics industries, gypsum PLA is the preferred product for modeling due to its high formability. Objects printed with gypsum PLA are very easy to shape, as they can be cut and filed with a sharp tool, making it easier to machine the object afterward. Painting is also easy, even with water-based paints. The last material used for sample and reinforcement production was ABS (acrylonitrile butadiene styrene), a widely used thermoplastic in the automotive, electronics, and engineering industries, valued for its high impact resistance and stiffness. While more challenging to print than PLA, ABS offers low shrinkage and allows for fast, precise processing in 3D printing, making it well suited for research. Its behavior in concrete--for instance, its  
Figure 1: Flowchart of the measurements and methods. solubility in NaOH solution simulating the pH of concrete--provides valuable insights for developing sustainable and innovative reinforcement strategies. These qualities make ABS an ideal choice for this study, aimed at exploring new reinforcement solutions. The casting molds were made from generic PLA, as they were designed to be single-use and needed to be quick and easy to dismantle. A total of six different materials were used during 3D printing, of which generic PLA was used only for the mold, and the other five materials were used for the test specimens. Furthermore, its solubility in NaOH solutions offers critical insights into its interaction with concrete media, contributing to sustainable and alternative reinforcement strategies.