# 3D-Printed Lightweight Foamed Concrete with Dispersed Reinforcement
## 3 Results and Discussions  
### Consistency and Flow Table Test  
The consistency, stability, and buildability of the mixture are critical parameters in the 3D printing process, particularly when utilizing foamed fiber-reinforced concrete. Stability ensures that the mixture retains its shape following the application of successive layers, while buildability refers to the material's ability to maintain its geometry without deformation or settling during the printing process. This section analyzes the macroscopic changes in the structure of foamed fiber-reinforced concrete through macro-photographic observations taken at various time intervals after mixture preparation. These observations provide valuable insights into the influence of time on the material's stability and formability under conditions representative of large-scale 3D printing. Such findings are instrumental in optimizing the mixture composition to achieve the desired performance for automated construction processes. Using the developed mixture design scheme, all mixtures were prepared, with a portion cast into molds for comparative analysis of flexural strength, while the remainder was subjected to 3D printing trials. Following preparation, the mixtures underwent flow table consistency tests conducted at three intervals: immediately after preparation, 20 min after preparation, and 40 min after preparation. The flow test results, obtained in accordance with the PN-EN 1015-3 standard, are summarized in Table 5. In cases where the mixture exhibited suitable consistency immediately after preparation, subsequent flow measurements were omitted, and the material was directly used in the extrusion process. Conversely, when the flow was excessively high, the mixture was allowed to stabilize until the appropriate consistency was achieved before proceeding with printing. The tests revealed significant differences in water demand between various materials, such as slag and fly ash. Similar variations were observed depending on the amount of foam incorporated into the mixtures. The results of the flow table test, conducted in accordance with the PN-EN 1015-3 standard, demonstrated a gradual decrease in flow diameter over time after the preparation of the mixture. This phenomenon was particularly pronounced in fiber-free mixtures, indicating a reduction in fluidity as time progressed. The type of additive used also significantly influenced the flow characteristics. Mixtures containing fly ash (FA) exhibited higher flow values compared to those incorporating bottom slag (SL), with the latter showing a stronger tendency to limit flow. This behavior can be attributed to differences in density and water absorption properties between fly ash and bottom slag. The incorporation of fibers into the mixtures notably reduced their flowability. The lowest flow diameter values were observed in mixtures containing polypropylene (PP) fibers, particularly at a concentration of 1% by weight. For instance, the B1/FA/PP1 sample exhibited a flow diameter of only 155 mm, the lowest recorded among all tested samples. A lower fiber concentration (0.5% by weight) improved the flowability of the mixture; however, the flow values remained significantly lower than those of the fiber-free mixtures. Mixtures with excessively high flow, such as B1/FA and B1/SL at the initial stage, required a waiting period of 20-40 min before printing could commence, allowing the mixture's consistency to stabilize. In contrast, mixtures containing fibers, due to their more compact structure, required less waiting time, although their reduced flowability often hindered the proper extrusion process.