Unfortunately cleaning is not a one-size-fits-all process for pavers. For example, masons will use muriatic acid on clay brick to remove mortar. However, muriatic acid could do serious damage to a concrete paver.
Generally, interior pavers that have been grouted and sealed just need to be swept, mopped, and spot-cleaned as needed with a gentle, non-acidic multipurpose cleaning solution, such as Enviro Klean All Surface Cleaner or Light Duty Concrete Cleaner.
Dilute white vinegar with water in a bucket, at Walmart (a 50:50 solution is fine), and apply this natural, eco-friendly cleaning solution to the paving slabs with a firm brush and rinse thoroughly.
Muriatic Acid is a very harsh and corrosive chemical that can quickly and permanently damage your stone.
Over time, it can destroy concrete as the acid weakens its structure. This will cause scaling, pitting, peeling, and cracking. If the acid wash gets into the soil, it will evaporate on the surface but remain beneath the surface (just like it does with concrete).
Scrub the acid solution: Once the solution is applied, lightly scrub it into the concrete with a push broom or long handled scrub brush. This helps to create a uniform etch of the concrete. Let the solution sit from 2 – 15 minutes while it continues to fizz and bubble.
To clean and etch concrete, mix one part muriatic acid to 10 parts water. Brush or spray the acid solution on the concrete, wait eight to 10 minutes, then neutralize the acid by spraying the surface with a mixture of one cup of ammonia in one gallon of water.
The reason you are seeing yellow spots on your muriatic acid cleaned pavers is because some of the aggregates used in making the pavers are now exposed. The reason for this is that muriatic acid attacks the pigments used to color the cement that is part of the concrete mix.
Don't pour muriatic acid down drains without neutralizing it, as this can cause corrosion and environmental damage.
Precautions to Take Before Using Muriatic Acid
Get the Proper Safety Gear: This acid will cause burns to the skin and eyes, and its vapors can even damage your respiratory tract.
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.
A dish soap, like Dawn, is a safe place to start. The surfactants in dish soaps are designed to remove oil and grease, they're gentle enough to be used without issue on your pavers. In a bowl or bucket, mix the soap with water and pour it onto the stain and agitate. Rinse and repeat if needed.
Yes, you can pressure wash your pavers. But while using a pressure washer at a basic level is simple, ignorant and inexperienced users can easily damage their pavers by using a stream that's too powerful, by holding the wand too close to the pavers, or by falling into any number of other rookie mistakes.
Mild detergent and water. If your pavers aren't too dirty, this can be a quick and easy way to clean them without any fancy equipment. Mix some mild dish soap with water in a bucket to create suds, then use a brush or a sponge to scrub the surface of the pavers.
Use a brick/block paver cleaner, or an acidic vinegar solution to clean the haze. Wash the surface with a pressure washer (medium pressure of 1600-2000 PSI ) to effectively get rid of haze without removing joint sand.
Like any strong acid, muriatic acid can irritate your skin (prolonged exposure can even cause burns). Gloves will help you avoid direct contact. If you do get muriatic acid on your skin, wash the area with clean water right away (it's a good idea to keep a garden hose or a bucket of clean water nearby).
And never ever mix muriatic acid with other cleaning products. Carefully apply that solution to any mold or hard surface and let it sit for about 10 minutes, then rinse it thoroughly with water.
Carbon dioxide (CO2)
oz. of 31.45% HCl. It takes 3.9 lbs of CO2 to equal 1 gallon of muriatic acid's pH impact, but CO2 will not reduce alkalinity. Carbon dioxide (CO2) is perhaps the purest, safest pH reducer on the planet.
Acids and acid-based cleaners can, and all-too-often do, cause devastating damage to the appearance of some types of paving. However, being wise after-the-fact is all too easy.
The calcium carbonate creates the whitish haze on the surface of the concrete pavers. As the moisture evaporates off the surface of the pavers, the whitish haze becomes more pronounced. And as naturally as the efflorescence appeared, it will fade.
A common problem that often arises with newly installed pavers is the appearance of a white haze that won't seem to come off. The most likely cause of this is a naturally occurring phenomenon called efflorescence.
Muriatic acid will quickly liquify most metallics, consisting of iron, copper, and light weight aluminum. It can easily additionally diffuse cement, rock, mortar, as well as grout. Additionally, muriatic acid will take out blemishes from rugs as well as cloth.
Muriatic acid is strong enough to etch concrete, but it can also cause severe injury and/or damage property when used improperly. Always wear protective clothing, rubber gloves, boots and goggles or a face shield when handling acid. Avoid breathing acid vapors.
Any concrete that is not properly neutralized will begin decomposing immediately. It may take time for the damage to reach the surface where you can see it, but it is happening and is usually irrepairable.