As a last resort, apply muriatic acid. Muriatic acid can work wonders on filthy concrete. However, it shouldn't be used on penetrating sealers since it can damage these finishes. It might also damage some acrylic sealers, so test a small area if you're not sure.
Washing Your Driveway
Use a solution of one part muriatic acid to ten parts water to clean your driveway. Dilute the muriatic acid and pour it into a plastic watering can. Wet your driveway with water, then start at the highest part of the driveway and sprinkle acid over the full driveway surface.
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.
Cleaning concrete with muriatic acid can be a highly effective solution if used correctly, providing ultra-bright white concrete and removal of many types of stains. In one application, you can remove rust stains, oil stains, algae, and paint splatter with a quick chemical application followed by pressure washing.
One of the most common methods of removing stubborn dirt and stains on outdoor concrete floors is by using muriatic acid. Muriatic acid is one of the most common substances when it comes to household cleaning and disinfection.
Muriatic acid will dissolve most materials such as metals, plastics (with exceptions), and finishes, which is why it is so effective in removing asphalt. A solution of muriatic acid diluted with water is applied to the surface, allowed to foam up, and rinsed away with water.
The most common acids used to clean concrete and bricks are hydrochloric acid (muriatic) or phosphoric acid. For many years it has been the standard cleaning method to prepare concrete for coatings installations, to remove stains of any type from concrete and to remove concrete slurry or efflorescence from bricks.
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).
While it corrodes almost anything it touches, this is not true of concrete. The acid works well on concrete and on many masonry projects because it neutralizes alkalinity. The surface becomes “etched” and clean, which allows for the proper adhesion of a new coating.
Only use muriatic acid after removing all other acids. It's vital that it's not mixed with other types of acid. Doing so will result in dangerous reactions. These acids will dissolve concrete but they will also damage pipes if used incorrectly.
When diluting it, pour the acid into the water, not the other way around. 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.
Muriatic acid may damage concrete surfaces, so be careful when pouring it on sidewalks or driveways; new concrete typically does not need to be cleaned at all before applying staining agents. If you do pour some on these surfaces, rinse off with lots of water as soon as possible.
When pavers, concrete or bricks lose their original beauty and dirt becomes embedded in the surface and before you seal your patio or driveway for the first time, it is necessary to acid wash your product. PREMIER-ACID-WASH makes this process simple and easy with clear instructions to follow.
No, you can't pour muriatic acid outside.
Doing so would kill plants and harm the soil, and the acid could leach into groundwater.
If the pH is below 6.0, residual acid remains in the concrete pores and must be neutralized. A neutralizing solution of two pounds of sodium carbonate (aka baking soda) in five gallons of water or a strong ammonia solution will usually neutralize the concrete in one application.
Add 1 part of 33% hydrochloric acid to 2 parts water to make a 10% solution. Always add acid to water and wear eye protection, acid proof gloves and all other appropriate protective equipment. 4. Apply liberally to cover the floor using a large watering can.
You can buy a commercial detergent at the local hardware store but we found a few household items will also do the trick. Washing Soda: Add ½ cup of washing soda to 4 litres of hot water. No washing soda? Just sprinkle powdered dishwashing detergent over the entire driveway.
But that's not all; chlorine bleach can also be used for cleaning the concrete driveway. Of course, you should dilute it with equal parts of water or a 1:1 ratio. With the mixture ready, spray it on the driveway, allowing it to sit for 10 minutes. Then, use a stiff brush before rinsing with clean water.
concrete can deteriorate. Freezing of trapped water, the effects of sea water, even certain bacteria and fungi can damage it. Particularly damaging to concrete are acids.
Generally, the best concrete mix for your driveway should have a compressive strength of at least 3500 psi to 4000 psi, a cement-water ratio of around 0.50 to improve the concrete's longevity, and aggregates no larger than 1-inch in size with a slump of 4 to 5 inches.