Concrete, known for its strength and versatility, can also provide a range of aesthetic options.
Once painted, its range of color possibilities is virtually limitless — as long as you choose the right kind. But what happens when the concrete dries? Will the dull grey of freshly poured concrete transform into a splendid work of art?
There is a lot of debate surrounding the colors of concrete as it dries.
Some people say that the color changes as the material cures, while others claim it is simply an optical illusion caused by the way light reflects the surface. So which is it? Does concrete change color as it dries?
Yes! The color of concrete can change as it dries, as the colors are affected by the ingredients and proportions used in the mixture and the finishing techniques employed.
Cement, sand, aggregate, and water contribute to the final hue.
For example, if there’s more cement in the mix than sand or aggregate, the concrete will be a lighter color. Conversely, if there’s more sand or aggregate than cement, the concrete will be darker.
And when water is added to this mixture, it can also affect the color of the finished product. So that’s why you might see different shades of gray or brown depending on how wet the concrete is when it’s being poured.
The Process of Concrete Color Changes As it Dries
The curing process is what causes the colors of concrete to change as it dries. The water in the mixture begins to evaporate, and as it does, the cement starts to harden.
This chemical reaction causes the material to shrink slightly and cause cracking. So during the curing process, you might see a color change from light to dark.
The concrete color changes as it dries, in the same way, paint dries and develops a different hue than when wet or fresh out of the can.
The same is true for concrete. But the color change is most evident when the surface has been finished with a sealant or other protective coating because these coatings can darken over time due to exposure to sunlight, weathering, and wear from foot traffic.
All of which cause oxidation in paint pigments and other substances (including some types of concrete).
Different Factors Affecting Concrete Color Changes
Aside from the ingredients themselves, different factors can also affect the color of concrete as it dries. These factors may include but are not limited to:
Weather Conditions
Temperature, humidity, and air pressure can all play a role in how the concrete dries and changes color.
When the humidity levels and moisture in the air are high, the concrete will dry more slowly and may take on a darker color. Alternatively, if the humidity levels or moisture in the air are low, it will dry faster and take on a lighter tone.
This is because concrete is a porous material and will absorb more moisture when the humidity levels are high and less moisture when they’re low.
Finishing Techniques
The way in which you finish concrete can also affect its color. For example, if you use a sealant on the surface, it will usually be a light color such as white or clear. If you use an anti-slip coating, it will usually be dark in color, such as red or black.
The finishing techniques used on the concrete can also affect its color, mainly if they’re applied after pouring but before drying.
Type of Concrete
The type of concrete used can also affect how quickly it dries and changes color.
Cement-based concretes tend to dry slower than other types like polymer cement mixtures because the cement needs time to hydrate with water before hardening completely.
Pouring Technique
The way in which the concrete is poured can also affect its final color. If it’s poured in a thin layer, it will likely be lighter in color than if it’s poured in a thick layer. And if there are any air pockets in the concrete, it will be lighter in color than if there are none.
How Long Does it Take for Concrete Colors to Change?
The duration of the concrete color change depends on many factors, including but not limited to: how thickly it was poured (a thinner layer will dry faster than a thicker one), whether or not there were any air pockets in the mixture when pouring (air pockets can slow down drying time because they trap moisture inside).
Generally speaking, though, it will usually take between 24 and 48 hours for the concrete to change from its wet state to its dry state. And depending on the finishing techniques used, it may take a few days or weeks for the color to stabilize.
Final Thoughts
Concrete is a versatile material that can be used in many different ways, and the color of concrete can vary depending on the ingredients and techniques used.
It’s essential to remember that how dry the concrete appears is not always an accurate indication of how long it will take for the color to change.
As a general rule of thumb, if you’re using a darker shade than what’s expected, then wait at least 24 hours before applying any finishing techniques such as acid staining or clear coats because these can affect the way light reflects off of concrete surfaces.
If you’re using a lighter shade than what’s expected, then it might be best to allow for up to 48 hours before applying finishing techniques.
This way, any moisture trapped beneath these layers will have time to evaporate and cause discoloration issues with your project over time if left untreated. In some cases, concrete may take as long as two weeks for its full color to develop.
