Your first step should be flushing and scrubbing the concrete. This involves soaking the concrete in hot water and then scrubbing it forcefully with a hard brush. The goal here is to even out some of the variability in the concrete's moisture and mineral build-up.
Load up a pump sprayer with good ole white vinegar. Spray the whole slab with it. Leave it sit 15-20 mins. Rinse slab off thoroughly. It will all lighten up to that nice fresh poured/cured white concrete look. Might not take it 100% away but it won't be noticeable unless you're staring at it too long.
The best way to fix it is to tear it out and repour with an exposed mix, usually 70 % stone, the rest of the mix is sand and cement. Place it, screed it, making sure there are no holes. If there are, fill them with the mix, not with cream like regular concrete, because the cream will wash out.
Concrete will continue to lighten until it is fully cured. Allow the concrete to cure at least 30 days before inspecting it for color match or appearance.
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.
If there isn't enough water, the crystals can't grow and the concrete doesn't develop the strength it should. If there is enough water, the crystals grow out like tiny rock-hard fingers wrapping around the sand and gravel in the mix and intertwining with one another.
This discoloration is usually removed by high-pressure washing with high-pressure water and, if necessary, chemical cleaning agents. The use of calcium chloride on concrete can discolor the surface.
To repair spalled concrete, start by removing the damaged portions and cleaning the area thoroughly. Then, apply a bonding agent and use a suitable patching material to restore the surface. In cases of significant damage, resurfacing the entire area may be necessary.
Different mix designs are going to be a common culprit. Every component of the concrete – not just the pigment – will affect final color. White cement will result in a lighter shade while gray cement will be shaded darker. The color of sand and/or aggregate will also affect final color.
A common sign of concrete failure is cracks. A few small hairline cracks that aren't actively growing and spreading are not necessarily a big problem. But larger, growing cracks are an issue that can affect your home's water drainage, affect the aesthetics, and damage your concrete's structural integrity.
Some contractors use one or more muriatic acid washes to artificially weather concrete. Others suggest first etching the surface, then washing it with a mixture of carbon black and water. A third alternate is using a diluted black or brown concrete stain to darken the color.
For Removing Mottling (Light Spots): Apply a solution of 12 ounces of sodium hydroxide by weight in 1 gallon of water. Leave on the surface for 24 hours. Rinse the surface thoroughly with clean, clear water and allow to dry.
Assuming that it is structurally sound, the least expensive alternative is to patch it. However, patching it requires some attention to detail or your patch will not last. Fact: Fresh wet concrete does not normally bond well to existing dry concrete.
If you're looking for a way to completely cover or erase imperfections in your concrete floors, your best bet is to have an epoxy applied. Epoxy has come a long way over the years. Today's epoxy floors are far more dimensional and stunning than the epoxy floors of the past.
Through careful grinding or sanding the surface of the dried concrete, you can remove rough patches, uneven areas, or imperfections, gradually achieving a smoother texture. Another approach is patching and filling.
Small variations in concrete moisture are common and typically not objectionable. But modifying mixes in the field, followed by inefficient mixing, can produce a blotchy appearance.
In order to patch concrete, you'll need the patch material or product, a concrete trowel, and a concrete rubbing stone. Mix the patch material if it's not a ready to use product and trowel in into the effected area, smoothing it out as best you can.
To ensure proper curing, there are several key things to ensure optimal results. Spray: To maintain the proper moisture levels, concrete should be sprayed with water frequently. This is known as moist-curing. Most specialists recommend watering the slab 5 to 10 times per day for the first seven days.
Concrete is usually dry enough after 24 to 48 hours to walk on. For concrete to dry and reach its full strength, it typically takes about 28 days per inch of slab thickness. Once conditions are conducive for the concrete to cure at 85-90% relative humidity.
Dry pouring does eliminate the step of mixing the concrete first, but you still have to prepare the subgrade, set up the formwork, and use a screed to level off the dry concrete before spraying it periodically with water, so very little time is saved overall.