## 3 Results and Discussion
### Characterization of Fiber-Cement Nanohybrids
#### 3.2.3 Crystallographic Analyses (XRD)  
The fact that no significant Ca(OH)\({}_{2}\) consumption or carbonation took place was also confirmed by the XRD analyses executed indicatively on F.PC60 LS40 PVA3 SP2 and the 1% nC3 and nC4 addition at day 28, as shown in Figure 10.  
Figure 9: Differential mass loss of fiber–cement nanohybrids based on F.PC60 LS40 PVA3 SP2 between 100–200 \({}^{\circ}\)C at (**A**) day 28, (**B**) day 56, and (**C**) day 90.  
Having completed the flexural strength tests, the thermal gravimetric and the crystallographic analyses, it can be observed that the nC2 and nC3 modified fiber pastes showed improved flexural performance; however, the difficulty of compaction of such pastes incorporating fibers and nMt can lead to increased clustering of the various particles, leading to greater strength variations. Improvements could firstly involve the nMt production method. Maybe less organic modifier should have been used for nC2 [19]. Carbon seemed to be applying a critical barrier by covering the platelets, possibly not allowing them to react as intended as stated in literature [19]. It is also possible that the excess of the organomodifier had a physical effect, as well, making the platelets re-agglomerate rather than keeping them apart. In future research, advanced ball milling techniques for the production of OMMT with anionic or non-ionic surfactants without any added water can be employed for better intercalation and thermal properties [50].  
Moreover, PVA fiber content could be reduced to 1%. This would also make the nMt's in the samples be more homogeneously dispersed. Future research could include studies of fresh properties, including consistency tests in order to optimize the formulation design with respect to the fiber and superplasticizer content.  
Possibly, both OMMT's (nC2 and nC4) were primarily intercalated rather than exfoliated. If they were fully exfoliated they may have performed better, as the charge would have made the platelets repulse each other and they; therefore, would have been individually available for reactions. In other words, their significant surface area would have been better utilized. Particularly in the case of the powder nMt, nC4, the platelets may have re-agglomerated within the hydrating paste. All results; therefore, suggest that nMt's should be better employed in aqueous dispersions if to be used in cementitious formulations. Adding to this, according to literature, montmorillonite K-10, on which nC4 is based, is produced via calcination [51], which is a CO2 intensive process. The above results indicate that there should be a shift towards non-thermally treated montmorillonite, as the calcined ones do not offer such enhancement that can counteract the damage to the environment.  
The inorganic nC3 dispersion was proven to contribute to flexural strength enhancement through the pozzolanic reaction. However, further research is required with respect to impermeability characteristics of pastes modified with nC3, as a tendency to adsorb water was observed in pastes containing only _PC_ and _LS_. Pastes containing _PC_, _LS_, and FA, showed enhanced performance by  
Figure 10: XRD pattern of fiber–cement nanohybrids based on F.PC60 LS40 PVA3 SP2 at day 28—effect of nMt type.  
adsorbing less water than the reference paste, but further research is required with respect to later age performance.