Pigment dosage in cement, mortar and concrete.

How to Properly Dose Pigments in Cement, Mortar, and Concrete

Coloring cement with powder pigments is a well-established technique in architecture and construction. It is essential to apply the correct dosage in each case to achieve the desired shade. In this article, we explain how to properly dose pigment when mixing it with pure cement, concrete, or mortar.

What is pigment dosage and why is it so important?

The pigment acts on the cement content of the mixture, so it’s important to know the exact amount of cement in order to calculate the right pigment dosage. The pigment ratio will determine the color intensity (softer or stronger) of the final product.
(For example, for a 4% dosage, you would add 4 kg of pigment for every 100 kg of cement.)

Dosage for:

1. Pure Cement:

Dosage: A standard dosage ranges from 2% to 5%.
Color Intensity: You can obtain many different shades from the same pigment reference. A higher dosage results in deeper, more vibrant tones; lower dosages produce lighter, softer shades.
Recommendation: If you are aiming for very intense or dark tones, dosage can go up to 8%. However, note that beyond this percentage, color saturation is typically reached.
White Cement: Lower dosages are usually sufficient since you’re starting from a white base, resulting in cleaner, pastel colors.

2. Mortar (sand and cement):

Dosage: Typically between 0.5% and 1% of the total mortar weight.
Considerations: The type and color of the sand can influence the final result. We recommend testing a sample with the specific mortar mix to be used.
Note: Pigment acts on the cement content in the mortar. Depending on the mix, the mortar may contain more or less cement, so it’s important to consider this when adjusting pigment dosage.

3. Concrete (aggregates, sand, and cement):

Dosage: Between 2% and 5% of the cement weight. In ready-mix trucks, a common dosage is 10 kg/m³.
Applications: Pavements, architectural elements, walls, urban furniture.
Considerations: Pigment dosage should always be based on the amount of cement in the mix. For correct dosing, it is essential to know the type of concrete and the amount of cement per m³.

Factors That Affect the Final Color

Several factors can influence the aesthetic outcome of pigmented concrete:

Cement Type: White cements produce brighter colors; grey cements tend to dull the shades.
Curing: Proper curing and consistent hydration are key for even color.
Aggregates / Sand: These can alter the perception of the final color.
Water-to-Cement Ratio: More water generally lightens the color.

Technical Tips for Ensuring Uniformity

Always dose pigment based on the weight of the cement, not the total volume.
Use precision scales for small quantities.
It is advisable to perform preliminary tests using the same materials and proportions as the actual project.

Which Pigment Should You Choose?

SC Pigments® are premium-quality inorganic pigments specifically formulated for mixing with cement, mortar, and concrete. They comply with the UNE-EN 12878:2005 standard, ensuring durability and resistance to UV rays.

If you’re unsure how to dose pigment correctly for your mix, feel free to contact our technical team—we’re here to help.

The Deepest Black Pigment

Achieving the deepest black possible is a challenge. In this article, we first analyze the most advanced black pigments in the industry, such as Vantablack and MIT’s Blackest Black, and then focus on specific and technical options for using black pigment in concrete for modern construction.

Advanced Deep Black Pigments

Among the most notable advancements in black pigments are Vantablack and the pigment developed by MIT—revolutionary materials in terms of darkness and light absorption. However, these pigments were primarily designed for space missions and scientific and technological applications.

These materials can absorb more than 99.95% of visible light, eliminating virtually any reflection. They are composed of carbon nanotubes and are not considered traditional pigments but rather advanced coatings that require specific application conditions.

The Deepest Black in the Art World

In the art world, contemporary artist Anish Kapoor obtained exclusive rights to use the Vantablack pigment in his projects, making him the only artist authorized to work with this black pigment.

Vantablack in Architecture

Vantablack was originally developed for space missions and scientific applications, but it also caught the attention of the architectural world. This led to the creation of the Hyundai Pavilion, designed by British architect Asif Khan for the 2018 Winter Olympics in South Korea. This pavilion is coated with Vantablack and is considered the darkest building in the world, creating the illusion of a deep void or a portal to outer space.

Regarding Vantablack’s application in architecture, it is important to note that this material is not a traditional pigment. Its application requires specific conditions and advanced techniques, which significantly limit its use in conventional architectural projects.

Black Pigment in Concrete: Innovation and Limitations

For concrete, there are several black pigment options that vary in intensity, durability, and ease of application. The most commonly used option is iron oxide black (SC Pigments References 51, 53, 55). These pigments are UV-resistant and ensure complete color stability for both interior and exterior applications. Iron oxide pigments are ideal for achieving gray tones, which can be lighter or darker depending on the dosage applied. However, when a project requires a more intense black, this pigment needs to be enhanced with another type of pigment.

To achieve very dark tones in concrete, carbon black can be used—the most intense and opaque black pigment available, capable of producing deep black shades.

The Solution for Deep Black in Concrete

Our Intense Black 5990 pigment is an ultrafine formula that incorporates carbon black, enabling blacks that cannot be achieved with iron oxide pigments. To ensure optimal color results, we recommend prior consultation, as its application may require more precise control to achieve the desired shade.

Find more technical information on SC Pigments’ iron oxide black pigments and the Intense Black 5990 pigment at this link.

How does the type of material affect the color?

We have conducted an example by pigmenting different materials using the same color reference and the same dosage based on the weight of the cement to analyze the factors that must be considered to achieve the desired color with cement, mortar, and concrete.

1 · Type of Cement

Different types of cement can interact differently with pigments and affect the final color. White cement produces cleaner and brighter colors compared to gray cement, due to its lighter base. Gray cement will always slightly darken the final tone, depending on the shade of the base gray.

2 · Dosage

The pigment dosage is related to the amount of cement in the mix. Depending on the dosage, the color will be more intense or softer. In this case, the pigment dosage relative to the cement is the same in all samples, but for example, mortar, which contains much more sand, significantly lightens the final tone.

3 · Aggregates

Depending on the type of aggregates used in the mix, the final result can be slightly lighter or darker. It is important to choose the appropriate aggregates for each specific application to achieve the desired material performance.

4 · Water

Maintaining an appropriate water-to-cement ratio is crucial for achieving consistent color results.

5 · Curing and Environmental Conditions

Factors such as temperature and humidity during the curing process can influence how the final color develops and sets in pigmented cement.

All these factors must be considered to achieve the desired color tone. In the image, we can see all the color tests performed with different materials using the same pigment reference, and clear color differences are noticeable. For any inquiries about pigmentation in cement, mortar, and concrete, feel free to contact Serra Ciments, and we will guide you through all these aspects to achieve the best color result for your project.

Origins of Iron Oxides

Iron oxides have been used since prehistoric times. Prehistoric humans collected minerals from the earth, crushed and pulverized them to obtain powder, and then mixed the powder with different substances to create organic pigments for use as paints. These pigments were applied to various surfaces, including cave walls, to create rock art and decoration.

One of the main components in these paints is the mineral hematite, which is composed of ferric oxide, with the formula Fe2O3.

Organic pigments found in nature tend to be less stable than synthetic ones, as they are sensitive to UV light, which can cause discoloration or fading over time.

In contrast, inorganic pigments, designed to improve properties and durability, are resistant to light, adverse environmental conditions, and the alkalis in cement. For this reason, they are preferred for applications requiring high stability and durability, such as in construction and exterior painting.

When choosing pigments to mix with cement, mortar, and concrete, it is important to select those specifically designed for construction applications. SC Pigments’ inorganic pigments are formulated to ensure color stability and compatibility with cementitious materials.