One cup of bleach mixed with a gallon of water should do the trick. Simply combine the bleach and water in a spray bottle and apply directly to the pavers.
Use Vinegar or Bleach
If you are going to try this approach to remove mold or algae, first try a mixture of white vinegar and water to spray down the area and kill the mold.
Scrub with Bleach and Water
Common household cleaners shouldn't be used on natural stone surfaces, but household bleach is an exception when you need to scrub away mold as a practical and effective solution.
Similar to cleaning pavers with muriatic acid, avoid an intense concentration of bleach, as it can damage the pavers.
White vinegar is good for cleaning pavers, though it's also acidic enough to erode the stones' surface. Diluted vinegar can be used safely to clean paving stones, though it should be used sparingly and infrequently to protect your paving from damage.
Natural Mold Cleaner
A bleach solution also works to kill mold. Mix one cup of bleach in a gallon of water, apply to the surface and don't rinse. Mix a 50/50 solution of ammonia and water. Spray on the surface, wait two to three hours, then rinse.
It's essential to only use cleaners which are appropriate for natural stone surfaces. This means avoiding using vinegar. Stones like limestone, marble, or travertine will react to vinegar because it's an acidic cleaner with harsh effects. It can even lead to burning or etching to occur on the surface of the stone.
Mold generally looks slimy or fuzzy, tends to have a raised texture, and can come in a rainbow of colors, including deep green and black. Mildew is powdery, looks white or gray, always appears flat, and grows on surfaces.
Water and mild dish soap is a popular cleaning solution because it's easy to find at home and it won't damage brick, but it will tackle stains. The BIA recommends using hot water for surface cleaning with a detergent. White vinegar and water, another common household cleaner, can also be used on mildew.
The simplest answer is no, it is best to avoid bleach when cleaning any type of natural stone. Many home cleaning products, particularly bleach and vinegar, are too harsh or acidic to be on natural stone. These cleaners strip down the stone and leave it in a weak, damaged state.
To clean paver slabs, you can use a detergent, such as Dawn, or a vinegar-water solution that is gentle enough to effectively clean without causing damage to your concrete pavers.
There are useful tools for cleaning paving stones, such as joint scrapers, sweepers, and pressure washers. In addition, pavers can be cleaned with a small pickaxe, broom, and garden hose.
OxiClean is a powerful concrete cleaner that works well on various materials, including pavement and grout. This concentrated solution provides excellent cleaning without leaving residue.
Clean stone surfaces with warm water and a mild soap such as a clear Dawn Liquid Soap. Do not use products that contain lemon, vinegar or other acids on marble or limestone. Rinse the surface thoroughly after washing with the soap solution and dry with a soft cloth. Change the rinse water frequently.
On granite, sandstone, slate, or quartzite, you can use a 1/2 teaspoon of hydrogen peroxide or a few drops of ammonia directly on the stain and remove it with a damp cloth. Use your normal cleaning solution on marble, limestone, onyx, or travertine.
Basic Cleaning Routine
First, sweep or dry mop your pavers. This eliminates dirt and debris so that scrubbing them is easier. Then carefully wash your stone pavers using a pH-balanced neutral cleaner and warm water. A sponge or sponge mop is an excellent tool for this job.
Cleaning vinegar contains about 6% acetic acid. While vinegar will kill the mold, it is slow acting, and the discoloration and stains from the mold may remain and require additional scrubbing with another household cleaner.
To Prevent Mold Growth in Your Home
Keep humidity levels in your home as low as you can—no higher than 50%–all day long. An air conditioner or dehumidifier will help you keep the level low. You can buy a meter to check your home's humidity at a home improvement store.
Warm water and mild antibacterial dish detergent is effective on mildew. Mix a solution of white vinegar diluted with water to clean up light mildew stains. Spray full strength vinegar to eliminate heavy accumulations of mildew.
Leave the white vinegar for 1 hour or so to let the vinegar work its way into the paver slabs. Spray the surface with soap and water, then scrub off. Rinse with warm water, then let dry. You may repeat the process if there are stains left.
On the other hand, baking soda is useful because it is slightly abrasive, which is excellent for the rough surfaces of paving slabs. When it is mixed with water, it can dissolve dirt and grease, and like vinegar, you'll only need a brush or broom when cleaning.
Although bleach is great at the whitening effect, you can use peroxide to achieve this. Hydrogen peroxide is an oxygenated bleach. It is safe for plants, so when you rinse this solution, it won't harm anything. It works together with the dish soap and baking soda to remove dirt and whiten dirty concrete.