# 3D-Printed Lightweight Foamed Concrete with Dispersed Reinforcement
## 3 Results and Discussions
### Water Absorption
Faster printing speeds or insufficient extrusion pressure can result in incomplete filling of gaps between layers, increasing porosity and water absorption, particularly in the vertical orientation. Figures 15 and 16 present the water absorption behavior over time, analyzed in both vertical and horizontal orientations, for molded and 3D-printed samples. Molded samples exhibit generally uniform and stable water absorption patterns, characterized by lower initial absorption rates. This behavior reflects a compact and homogeneous internal structure resulting from the mold casting process, which restricts water penetration. In horizontal orientations, water absorption patterns are similarly stable, with smaller differences between individual samples compared to 3D-printed specimens. The latter demonstrates higher variability in water absorption, which can be attributed to imperfections in the printing process and inconsistencies in layer arrangement. Printed samples tend to absorb water more rapidly, especially during the initial testing phase. For instance, the molded B1/FA/CO1 sample in a vertical orientation records a water absorption coefficient of 4.2 kg/m\({}^{2}\) after 1 h and 26.5 kg/m\({}^{2}\) after 6 h. In contrast, the 3D-printed equivalent under identical conditions exhibits absorption values of 12.6 kg/m\({}^{2}\) and 29.4 kg/m\({}^{2}\), respectively--nearly three times faster during the initial phase. A similar trend is observed in horizontal orientations. For example, the molded B1/FA/B1 sample absorbs 18.8 kg/m\({}^{2}\) after 1 h, while the 3D-printed counterpart absorbs 20.9 kg/m\({}^{2}\), representing an approximately 11% higher initial absorption. However, after extended exposure (7 days), the water absorption of molded and printed samples converges, with minimal differences. The vertical B1/FA/CO1 molded sample shows a final absorption  
Figure 15: The water absorption coefficient for printed samples: (**a,c**) samples containing 1% fiber content, (**b,d**) samples containing 0.5% fiber content. of 52.1 kg/m\({}^{2}\) compared to 52.6 kg/m\({}^{2}\) for the 3D-printed sample, indicating that the total water-holding capacity of 3D-printed samples may be slightly lower due to their higher density and reduced void volume. Both molded and printed samples display significantly lower water absorption coefficients at lower fiber concentrations (0.5%) than at higher concentrations (1%). For example, the printed vertical B1/FA/CO05 sample (0.5% coconut fibers) absorbs 9.6 kg/m\({}^{2}\) initially, rising to 37.6 kg/m\({}^{2}\) after 7 days. In comparison, the B1/FA/CO1 sample (1% coconut fibers) absorbs water more rapidly, with slightly higher final values. A similar pattern is evident with basalt fiber samples: the printed B1/SL/B05 sample (0.5% basalt fibers) absorbs 7.2 kg/m\({}^{2}\) initially and 23.8 kg/m\({}^{2}\) after 7 days, while the B1/SL/B1 sample (1% basalt fibers) absorbs 13.5 kg/m\({}^{2}\) initially and 39.0 kg/m\({}^{2}\) after the same period. Molded samples follow comparable trends, with final absorption values slightly lower than their printed counterparts. Horizontal sample placement typically results in higher initial water absorption than vertical placement, regardless of the production method. Samples containing hydrophilic fibers, such as merino wool, exhibit markedly higher initial water absorption. For instance, the printed vertical B1/FA/M05 sample absorbs 42.8 kg/m\({}^{2}\) within the first hour, significantly exceeding the B1/FA/PP05 sample (15.1 kg/m\({}^{2}\)). After 12 h, the values increase to 51.1 kg/m\({}^{2}\) and 26.1 kg/m\({}^{2}\), respectively. By the end of the 7-day testing period, the final  
Figure 16: The water absorption coefficient for molded samples: (**a,c**) samples containing 1% fiber content, (**b,d**) samples containing 0.5% fiber content. absorption for the B1/FA/M05 sample reaches 60.6 kg/m\({}^{2}\), compared to 34.4 kg/m\({}^{2}\) for the polypropylene-reinforced sample.