How to Remove Concrete Coatings

2020-02-03

Technology has created concrete coatings that are meant to last. This makes removal time-consuming and difficult, but not impossible. There are several techniques you can choose from to take off a coat of sealant, paint or epoxy from a concrete surface.

Stripping It Down

There are two basic methods for removing concrete coatings: mechanical and chemical. Mechanical methods include grinding, sandblasting and sanding. These methods are time-consuming, create a lot of dust and can possibly damage the concrete. They allow you to avoid the use of chemicals, however, and can smooth out a rough or uneven surface. Chemical strippers create a reaction that causes the coating to release from the concrete surface so that it can be wiped or scrubbed away. Chemicals are less labor-intensive, but pose serious health hazards if handled or disposed of improperly. Adequate ventilation is also necessary. Chemical stripping options include biochemical, solvent and caustic. Each works in a slightly different way to achieve the same results. Although some are touted as being less harmful to the environment, all pose serious risks, such as severe burns, if proper safety precautions aren't used.

Here are three ways to remove concrete coatings.

1.     Acid etching – low cost, fast and effective

How to clean concrete before sealing using acid etching requires caution  due to the possible health problems and the damage it may do to plants, clothing or nearby equipment. This article will describe the basic process, but you must follow the safety instructions given to you by the seller of the product or as indicated on the label. Being tidy and careful is the key to using acid successfully.

Hydrochloric acid which is mainly sold for brick cleaning will attack the lime in the concrete and dissolve the bond. When it is used to clean a concrete floor, driveway or pavement it is quickly neutralized or mostly neutralized on contact or when the fizzing has stopped so it only acts on the surface. Usually a mix of 10 parts of water to one part of acid will be strong enough to remove the polish from the surface.

If you wear correct protective clothing, gloves and eye protection and take care not to splash, the best way to apply the acid is with a long handled paint roller with a deep pile cover. Apply it liberally and slowly enough to prevent a spray.

After applying the acid/water mix and before it dries thoroughly water jet clean the concrete by blasting it with 3,000 psi close to the concrete with a fan jet, rinsing is not good enough to remove the surface particles and a rotary jet (like a lawnmower) is the best way. When the concrete is dry apply the first coat of paint.

2.     Shot blasting – hire a professional

This is better left to the experts who know what power of machine to use, what size shot and how fast each pass should blast the surface. These machines throw small steel balls at the concrete within a sealed chamber by passing the shot through a fast-spinning paddle wheel. The shot hits the surface, breaks it open and then bounces back up the return chamber to be recycled while a vacuum system separates and removes the dust and grit. Shot blasting can open the surface more than intended and leave deeper grooves where the blasting overlaps so it is not ideal for home applications.

3.     Concrete grinder – the best DIY

These devices come in all shapes and power sizes as well as wheel configurations, from small hand held angle grinders with a dust extraction shroud and diamond grinding wheel to sit-down versions large walk-behind machines that have multiple wheels underneath. For driveways that need only the edges opened at the surface an angle grinder set up as a concrete grinder is ideal. It will grind dry and the dust collector will remove all the dust as you work. For larger areas more than the edges a sit down grinder (see video below) or stand up grinder using an angle grinder as the motor source will be faster and easier. There is a dust extraction shroud that even gets into the corners and most have edging features to grind against walls.

They work by using a spinning wheel in contact with the concrete that has diamond segments welded to the wheel. As these diamonds come in contact with the concrete they wear away and grind off the top surface. The dust extraction shroud contains all the dust and the dust collector removes it without airborne particles. DTS Diamonds supplies PCD tools and Metal tooling specially for removal of concrete coating.

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