## 3 Results and Discussion
### Mechanical Properties  
Flexural strength could be considered among the most important mechanical property of gypsum boards. Flexural strength is crucial because gypsum boards are often subjected to bending stresses during handling, transportation, and installation. Higher flexural strength ensures that the board can withstand these stresses without breaking or cracking, leading to improved durability and ease of use. On the other hand, the most important mechanical property of cement building components is typically compressive strength. Compressive strength measures the ability of the material to withstand axial loads or forces that tend to compress it. It is a critical property for such structural materials because they are often used in load-bearing applications, such as walls and foundations. High compressive strength ensures that these components can support the loads they are subjected to without crumbling or failing. It provides stability and structural integrity to buildings and other structures constructed using these blocks. While other mechanical properties such as tensile strength, flexural strength, and shear strength are also important, compressive strength is particularly crucial for ensuring the overall stability and safety of structures built with cement building components.  
The results of mechanical testing on gypsum and cement boards with varying OD@CCF contents are presented in Figures 9 and 10, respectively. Analysis of load-deformation data from bending tests on GB/OD@CCF boards (Figure 9) indicates a clear relationship between additive percentage and composite board mechanical properties. At lower concentrations (up to 20%), a positive correlation is observed, indicating that OD@CCF inclusion enhances material strength, likely owing to enhanced interactions between molecules and the effects of reinforcement. However, with increasing OD@CCF content, a decline in mechanical strength is evident, possibly due to possible disturbance of the gypsum structure caused by elevated OD@CCF concentrations. As shown in Figure 9b, the optimal OD@CCF content for gypsum boards is found to be 10%. At this concentration, the modulus of rupture measures at 3.14 MPa, significantly higher than the 2.64 MPa for the reference gypsum board. This suggests that the mechanical strength of the composite board peaks at 10% OD@CCF content in bending tests.  
Figure 9: Curves representing (**a**) load–deformation and (**b**) modulus of rupture extracted from bending tests conducted on gypsum boards with varying loading of OD@CCF additive.  
The results of compression tests on cement boards (CBs) with varying percentages of OD@CCF additive are presented in Figure 10. The corresponding parameters from these tests are outlined in Table S3. A minor reduction in compressive strength is noted with increasing OD@CCF loading, decreasing from 1.09 MPa to 0.96 MPa for 10% and 20% loading, respectively. However, with a higher OD@CCF loading of 30%, this reduction is more pronounced, resulting in a compressive strength of 0.81 MPa.  
In comparing the building boards (GB and CB), the inclusion of OD@CCF boosts the modulus of rupture by approximately 19% for 10% and 20% additive in case of GB, while this value is reduced by 16.6% for higher contents (30%). On the other hand, in case of CB, the compressive modulus reduced by 2.5% for 10% and 20% additive and 41% for 30% additive (Figure S3d).