Compressive-Strength Analysis of High-Strength Cementitious Composites Mixed with Red and Green Pigments

We estimate the mechanical properties of pigment-containing ultra-high-strength cement composites (UHSCCs) and the pigment-induced changes in their physical properties via thermal and X-ray diffraction analyses. Hydrates in samples are analyzed using thermogravimetry. Additionally, the change in color expression with the UHSCC age is examined via the Commission Internationale de l' eclairage L*a*b* analysis. Correlation analysis is performed to determine linear relationships between experimental factors by calculating R-2. A change in hydrate expression is confirmed as the strength increases with age. The pigment used affects the change in hydrate expression as well as color development. Correlation analysis of the results for all ages reveals that 5% red pigment mixing yields the highest R-2 of 0.9858 in intensity-a*. The case of 10% red pigment mixing yields the lowest R-2 of 0.5229 in intensity-b*. According to the amount of pigment used, we believe that quantitative results can be obtained by considering L* (contrast), rather than the relationship between intensity and color components. The appropriate mixing ratio based on the intensity expression of the red pigment is 3-8%, and the green pigment intensity and strength expression are inversely proportional. Our results can serve as a guideline for the performance development of pigmented cement-based composites.