## 1 Introduction  
Unique building spaces have been developed over the years [1], and the construction of such buildings requires unique materials such as colored concrete. However, the addition of excessive amounts of pigments for coloration may degrade the workability and compression performance of concrete [2; 3; 4] because the pigments absorb the water required for cement hydration. Because the particle size of inorganic pigments is generally smaller than that of cement, the specific surface area of pigment particles in contact with moisture is larger, and the addition of excessive amounts of pigments can deteriorate the mechanical properties of concrete [5; 6]. Therefore, to minimize the reduction in strength or performance when pigments are added to concrete, white cement is typically used for color development. Various concrete products, such as precast concrete (PC), that can be customized with distinct colors have emerged in the construction industry [7]. Existing colored concrete products are evaluated based on three factors: brightness, saturation, and hue. The quantification of hues is necessary to standardize colored concrete products [8; 9]. Colored concrete,mainly produced by mixing pigments or using colored materials, is widely used in interior and exterior spaces. Its usability has been low because of its high cost and color durability caused by the mixing of pigments. Nevertheless, the demand for colored concrete is increasing with the increasing interest in designability [10]. Fine pozzolanic materials, such as ultra-high-strength concrete and ultra-high-performance concrete (UHPC), have been developed for use in interior and exterior finishing materials [11; 12; 13; 14; 15]. High-strength and high-toughness UHPC products can be used to realize shapes and colors in various environments because of the maximum hydration reaction induced by the initial steam-curing process. High-purity UHPC and binders with large specific surface areas increase the strength of conventional concrete because of the fast pozzolanic reaction of silica fume [16]. [PERSON] et al. revealed that mixing concrete with nano-silica increases its mechanical strength [17]. [PERSON] et al. found that materials with a large specific surface area can be added to UHPC to increase the internal density or prepare high-strength concrete specimens with a low water content [18]. Fe\({}_{2}\)O\({}_{3}\), a reddish-brown iron oxide, has been used as a nanoscale pigment. The addition of reddish-brown marble powder containing Fe\({}_{2}\)O\({}_{3}\) enhances the compressive strength in most curing periods as the pigment content decreases. [PERSON] and [PERSON] reported that the mechanical properties of concrete containing Fe\({}_{2}\)O\({}_{3}\) were enhanced because of an increase in the nanoparticle content. Strength tends to increase when a moderate amount of pigment is added. However, when pigments are added in large quantities, the mechanical properties are affected because the moisture content in the material decreases [19; 20; 21; 22]. Colored concrete can be used as an alternative material in challenging architectural designs and applications for multi-purpose features, including aesthetic elements. However, the mechanical properties of such materials need to be enhanced further [20]. Therefore, the properties of colored concrete with improved durability and color development must be evaluated for satisfying consumer demands resulting from an increase in the diversity of PC products. However, existing studies have not examined the hydration properties of pigment-added concrete. In this study, various analyses were performed to confirm the hydration properties of concrete containing pigments. To this end, colored ultra-high-strength cementitious composites (C-UHSCCs) mixed with red and green inorganic pigments were fabricated, and their strengths were measured according to their age and hydration state.