Muriatic acid to clean oil from concrete

Question: A dump truck left not only a load of topsoil at my home but also left behind an oil stain on my concrete driveway. I also have old stains on my garage floor.

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Try Alternatives First
Precautions
Washing Your Driveway
What is the best way to clean oil off of concrete?
Can muriatic acid damage concrete?
How long should muriatic acid sit on concrete?
Does muriatic acid eat oil?

How can I remove these stains and restore the concrete to its original state? Is there a way I can prevent oil stains from seeping into concrete?

Answer: Motor and hydraulic oils can cause a mess on concrete, brick and blacktop, but you can achieve excellent cleanup results if you act quickly.

Concrete is dense, but water and other liquids can soak into it. The fresh oil stain will be easy to remove. The older oil stains are tougher.

To remove the fresh stain, you will need a scrub brush, liquid dish soap and water. Squirt the soap onto the stain and add water. Scrub vigorously, adding enough water to make a rich lather. Wet down the surrounding concrete to prevent oil released during the cleaning process from causing a secondary stain.

The soap emulsifies the oil and lifts it out of the concrete. If you rinse the driveway, the oil will pollute your yard or street, so blot the dirty soap mixture with paper towels or a dry compound like cat litter and dispose of it in a certified landfill. Some stains require several scrubbings to remove the oil.

Do not use a wire brush to scrub the concrete. It can scratch the finish and result in a permanent scar. Use a nylon bristle scrub brush, which you can purchase at a grocery store.

Use the same method to attack the older stains in your garage. If the concrete finish is smooth, you have a greater chance of success. Smooth steel-troweled concrete is highly resistant to oil stains. Rough concrete finishes absorb oil rapidly.

If the old stains do not respond to the soap and water method, consider using a solvent like kerosene to help lift the stain. I do not like to use solvents, however, because they are dangerous to work with. Fumes from these products can ignite and cause serious harm to you and your home.

If you decide to work with solvents, do so only after consulting with your fire department's fire prevention officer.

Some people have had success lifting oil stains using muriatic acid, but this chemical, even when mixed one part acid to 10 parts water, dissolves some of the cement paste at the surface. Couple this with scrubbing, and you very well may alter the appearance of the concrete once it dries.

Clean concrete can be treated to help minimize the penetration of oil and water that contains dirt and pigments. Some of the best products are clear water and oil repellents that contain silane and siloxane ingredients.

These chemical solids help block the tiny pores in concrete to stop water from entering and soaking into the concrete. The easy-to-apply silane and siloxane products allow the concrete to breathe, which is important for concrete that is subjected to freezing temperatures.

Tim Carter is a licensed contractor. Got a question for him? Call toll free from 10 a.m. to noon today at (888) 737-1450 on his radio call-in show (not broadcast in the Tampa Bay area).

Dirty or stained concrete can be cleaned a number of ways, though some stains won't respond to any cleaners. For these stains, wash your driveway with a diluted muriatic acid solution. When working with any acid, take appropriate precautions, including protective clothing and safety gear.

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Muriatic acid is diluted hydrochloric acid and is a very potent chemical. It cleans concrete by removing the topmost layer of your driveway; use it only as a last resort to clean stains. Before washing your driveway with muriatic acid, try a degreaser on oil stains and a solution of one part bleach to three parts water on mold and mildew. Use vinegar or oxalic acid on rust stains and a pressure washer with an aggressive detergent such as trisodium phosphate for general cleaning. Phosphoric acid is less aggressive than muriatic acid and yields similar results. Fall back on muriatic acid if these methods fail, but first thoroughly rinse your driveway with clean water to remove all traces of chemicals.

Precautions

Some municipalities prohibit draining acid into the sewage system, so consult the local waste-water management agency to stay within the regulations.

Acid can be dangerous to work with, so don appropriate safety gear including acid-rated lung protection, goggles and acid-resistant rubber boots, gloves and coveralls. If you plan to clean the floor of your garage, borrow or rent industrial fans for ventilation. Wet down adjacent lawns to dilute excess acid or make a slurry of baking soda and water to neutralize the acid before it damages your plants.

When mixing acid, slowly add the acid to water to avoid a violent reaction. Because acid reacts with metal, mix muriatic acid in a plastic or glass container.

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. Applying the acid to only the stained parts of your driveway will unevenly discolor the concrete. When the surface is completely covered, scrub stains and spots with a stiff bristled nylon scrub brush. Do not let the acid sit on your driveway for longer than 10 minutes. Neutralize the acid with a generous amount of baking soda or garden lime and rinse the neutralized acid from your driveway.

What is the best way to clean oil off of concrete?

How to Remove Oil Stains from Concrete.

Remove excess oil - Wipe up oil with a rag or use cat litter to absorb it..

Scrub with a paste - Use baking soda or powdered laundry detergent and water to dissolve the oil stain. Rinse with water..

Wash with soap - Dish soap and a scrub brush are often effective on new oil spots..

Can muriatic acid damage 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.

How long should muriatic acid sit on 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. Do not let the floor dry out during this process.