Fresh concrete is always much darker than when it is fully cured and dry. Even uncolored concrete. Wait at least 7 to 10 days until the new concrete has hardened and dried. If the concrete is on a wet subgrade or there's underground water, it may stay dark for as long as it's wet.
Although the bulk of the hydration process takes place in the hours and days immediately after the pour, concrete needs 28 days to fully dry. While the slab will harden and lighten in color before 28 days, don't be fooled into thinking it's done hydrating.
The dark gray discoloration is caused by varying degrees of hydration of the cement in the concrete, caused by the varying moisture contents in the localized areas of the total concrete.
If the concrete can cure consistently, the end result is usually a quality concrete product with consistent color and finish. If a foreign object retards the movement of moisture out of the concrete or traps moisture at the surface, a curing differential occurs, resulting in a color shift in the concrete surface.
This problem is called curing differential, caused by different levels of moisture at the surface of concrete during the critical first few days to weeks after pouring concrete. So, uniform curing is key to producing a consistent color concrete surface.
If water is used to cure, a lighter color is likely. Be certain to use curing, sealing, and cure-and-seal products approved for use with colored concrete and follow manufacturer's recommendations for application. Concrete will continue to lighten until it is fully cured.
In its natural state, concrete has a light gray color. However, over the last few decades it has become common to color concrete a variety of different hues. There are many techniques for coloring concrete that produce different strengths of color.
The color of the sand affects the color of the concrete. High-strength concrete with a low proportion of water-cement is darker than low-strength concrete with a high water-cement ratio. proper placement, finishing, and processing timely curing.
What are the causes of concrete discoloration? Concrete discoloration is a change of designated color due to calcium chloride in concrete, cement and additives, improper curing, environmental conditions, and faulty finishing works. What are the drawbacks of a high concentration acid solution on concrete?
This image shows that when a surface is covered by water boundary, the light beams that face the surface, will absorb to it. So there would be less light beams in the area for arriving to our eyes. As a result, we see the material darker.
Excess Water
As the water evaporates to the surface and soaks into the cement that is an ingredient of concrete, it leaves behind darker spots where the cement contains more moisture. These will fade over time as the water eventually soaks into or evaporates out of the slab.
Sealers, particularly solvent-based sealers, will darken concrete. If unevenly applied, it will create light areas where there is less sealer, and darker areas where there's more. If applied by sprayer, it may appear like “stripes”. Uneven roller application may leave darkened roller marks.
Going from a light to a dark color can be achieved with tinted sealers and colored coatings. But to go from dark to light, without making the surface look like it has been painted, often requires application of a micro-thin colored overlay. However, this is a costly fix and will not work over exposed aggregate.
Concrete that is not moist-cured at all dries too rapidly, and reaches less than half its potential design strength. It will also have a greater number of shrinkage cracks.
DO spray new concrete with water. One of the most common methods for curing concrete is to hose it down frequently with water—five to 10 times per day, or as often as you can—for the first seven days. Known as “moist curing,” this allows the moisture in the concrete to evaporate slowly.
Concrete takes 28 days to fully cure. Concrete cure time allows the material to become as strong as possible. While you may be able to open up the freshly cemented area to light foot traffic after a day or two, let the concrete cure for 28 days before you allow any heavy machinery or other large objects on the surface.
Dark, blotchy appearance — When properly laid, concrete should look all the same shade, rather than showing dark blotches here and there. Light discolorations — Discolored concrete can also be seen in occasional patches of lighter than normal concrete in the overall surface.
Mold, black algae, green algae, and lichen can grow on your outdoor hard surfaces and make them appear dirty. Not only does it look messy, but it can be slippery and bring harm to your friends and family. Additionally, some strains can cause damage and be difficult to remove.
It involves wetting the concrete slab often with water (5-7 times per day) for the first 7 days. This method ensures your concrete slab will be extremely strong and durable, because it allows the moisture to evaporate slowly, preventing cracks and shrinks.
When the sealer is applied too heavily, the air displaced through the surface can't escape, and it forms a bubble in the sealer surface. Bubbling of a sealer can also occur if application is done in hot weather, or if the concrete is in direct sun.
The rule of thumb is lighter colors will make a room appear larger and darker colors make it seem smaller. Another side point to this same theory is that light colors show less scuffs, scratches and dirt whereas dark colors show everything. Often this is because light — natural or controlled — reflects off everything.
There are two ways you can take a dark stain and make the final shade lighter. First option would be to dilute the acid stain itself. Second option would be to wash the stain off earlier in the process. In addition a second test patch should be done before completing the project.
Best Colors for Outdoor Concrete Patios
If you want a patio that looks clean and simple, standard gray is a good bet. If you'd like your outdoor concrete patio to fade into your landscape more, a modern rust color can give the patio an earthy-look without drawing the eye to it too closely.
Fresh concrete is always much darker than when it is fully cured and dry. Even uncolored concrete. Wait at least 7 to 10 days until the new concrete has hardened and dried. If the concrete is on a wet subgrade or there's underground water, it may stay dark for as long as it's wet.