## 3 Results and Discussion
### Coefficient of Determination Analysis of Strength with TGA and Color Difference
This is because trends of continuous increases and decreases in the intensity expression, TGA (\(\Delta\)m), and color factors appear as the age increases. As observed from the R\({}^{2}\) analysis of specimens at all ages, for specimens P, R10, and G5, which showed an approximately constant intensity expression, the R\({}^{2}\) value for the correlation of strength with TGA (m) exceeded 0.5 at all ages. Among them, specimen P exhibited an R\({}^{2}\) value of 0.8546. In the case of colored samples, a high R\({}^{2}\) was measured at L* for P, a* for R5, L* for R10, and a* for the green series when the intensity was expressed. For the R series, a high correlation with the a* of the red-green series was calculated at a mixing rate of 5%, and the correlation with the brightness (L*) increased as the mixing rate increased. In the G series, the a* of the red-green series had the highest correlation with strength, irrespective of the change in the mixing rate. Therefore, it was possible to determine the correlation of factors partially related to strength expression in the specimens containing red and green pigments at all ages. Here, a* represents red-green color information and b* represents blue-yellow color information in such a manner that the strength is not affected by the pigments. Consequently, it would be effective to analyze the relationship between strength and color to understand the trend of L*, which indicates the brightness. Figure 10 shows the R\({}^{2}\) distributions between strength and the other factors at different ages. The distribution could be compared to the difference between the R\({}^{2}\) of a specific factor and that of the other factors at a certain age, as shown in Figure 9.  
The linear relationships between the experimental characteristics of the prepared HSCCs were identified. The correlation analysis matrices shown in Figures 9 and 10 illustrate the relative experimental trends of HSCCs based on the pigment type and mixing rate and exhibit unique R\({}^{2}\) values. This result could serve as a reference for determining the weight factors during the development of HSCCs in the future. According to previous studies, the strength decreases when pigments absorb some amounts of the mixing water intended for the hydration of unhardened concrete, and this decrease depends on the components and types of pigments used [4]. Furthermore, in the case of red pigments, pigment contents of 4% or 3-6% and 6-8% yield the optimal performance [1; 5]. In general, the green pigment shows a tendency of strength decrease with increasing mixing rate [1]. The results obtained in the present study show a similar trend. Existing studies have demonstrated the strength, fluidity, and slump results of mixing pigments in normal-strength concrete. However, these studies have not considered experimental formulations that could be used to determine the mechanical properties of high-strength concrete-containing pigments. Therefore, in the present study, we performed various analyses to develop an experimental formulation of the HSCCs and to identify correlations between strength and other experimental factors, except for fluidity and slump. Through the TGA estimation of the hydrate produced at different ages as well as the CIELAB analysis of the color development of pigments, we demonstrated that it is possible to verify the correlation distributions of the above factors in the intensity expression. In addition, for concrete structures and finishing materials that employ HSCs, the findings of this study could be used as a reference for determining the trend of strength development based on factors other than fluidity.