## 4 Test Methods  
In this study, various nanocomposites consisting of conventional nanocellulose and CNCs were investigated, and the suitability of CNCs for use in the field of construction was evaluated. The optimal conditions for dispersing CNCs in powder form through magnetic stirring and using high-pressure dispersion to prepare colloidal samples for use in cement-base composites were also analyzed.  
Nanomaterials experience van der Waals attraction, which is the primary reason for the aggregation of their particles. As the particle size decreases, the effect of the van der Waals attraction becomes more pronounced compared to that of the other forces. Sulfuric acid has been used to control the agglomeration of CNCs [11]. However, the direct dispersion of CNCs can be harmful to humans. Further, it can also cause the CNCs to chemically react with the cement. [PERSON] et al. [20] dispersed CNCs using sonication. They observed that the transparency of the dispersion varied with the sonication time. For a quantitative evaluation, they performed rheological measurements on freeze-dried CNC suspensions at 0 minutes, one minute, five minutes, 15 minutes, and 30 minutes. The thus-dispersed CNCs could move freely, in contrast to coagulated CNC suspensions. The total shear stress decreased with an increase in the ultrasonic treatment time. This type of mechanical dispersion allows the inherent properties of CNCs to be combined with those of cement, in contrast to the case for dispersion using chemical additives such as sulfuric acid. In addition, it was found that sonication is safe with respect to humans. Therefore, in this study, CNCs were mechanically dispersed (except for ultrasound dispersion) using a magnetic stirrer and a high-pressure dispersing machine. Figure 1 shows the raw CNCs, which were in the form of a powder, and a CNC suspension prepared using distilled water as the solvent. The physical properties of the CNCs and the dispersion methods used and the corresponding parameters are listed in Tables 3 and 4, respectively. In the case of magnetic stirring, the dispersibility was measured based on the stirring time, whereas for high-pressure dispersion, the dispersibility was measured based on the pressure and number of dispersion passes.  
High-pressure dispersion involves applying a pressure to the sample to be dispersed using a hydraulic system and a pump. The material is passed through a nanocell and is dispersed via the mechanisms of high shear, impact, and cavitation. This process is shown schematically in Figure 2. The high-pressure disperser that was used in this study was operated at pressures ranging from \(206\times 10^{5}\) Pa to \(2757\times 10^{5}\) Pa and at a flow rate of up to \(300\) mL/min. Generally, a pressure of \(1587\times 10^{5}\) Pa is used to disperse nanomaterials through high-pressure dispersion. In this study, high-pressure dispersion was performed at pressures of \(345\times 10^{5}\) Pa, \(1035\times 10^{5}\) Pa, and \(1587\times 10^{5}\) Pa, with one to three dispersion passes. The CNCs used in this study were very soft and in powder form; hence, the maximum pressure was limited to \(1587\times 10^{5}\) Pa, given the possibility of their ionization in water at higher pressures.