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As cliché as it may sound, there are two things that architects really like: exposed concrete and the color black. While concrete offers a distinctive rough aesthetic, emphasizing the tones, textures, and surfaces that shape the concrete mixture, the sobriety that the color black provides allows the architect to highlight specific characteristics precisely. Combining the two seems natural. But black pigmented concrete is not as common as we might imagine. Below we talk a little about the black concrete production process and some projects that use it. The concrete pigmentation process is not new. Experiments started in the 1950s, which involved nothing more than adding some type of pigment, in the form of powder or liquid, to concrete aggregates (sand and stone) when they were still dry, in an amount of 2% to 5% of the weight of the cement. The entire mixture becomes pigmented, although only a small part is visible. Specifically for black concrete, iron oxide (Fe3O4) is generally used, found in nature as the mineral magnetite. When added to the concrete mix, the iron oxide particles encompass and coat the cement particles, which are 10 times smaller. That is why the amount of pigment is dosed based on the amount of cement, not sand, gravel, or water. [1] View more View full description
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