How to Fix Old Concrete

Fixing old concrete may mean just re-doing a previous coating or floor system that needs maintenance, or starting over from scratch and reapplying a coating or it may include structural repairs of cracks, spalls and other defects in the concrete itself.

The first step in "fixing" older concrete is to first do an accurate and thorough survey of what conditions currently exist.

A starting point is to measure all the square footage involved (see Measure for help on that). Measuring right away serves two purposes:

  1. You know the exact square feet which later allows you to develop cost estimates for materials and labor, and
  2. Takes you over the whole area so you can inspect it in detail.

A detailed inspection and noting of problems can often give clues as to the cause of the problems you see. Knowing the causes then allows you to avoid them during this "fixing" process.

Sometimes coating or floor covering failures have underlying causes. Sometimes the problem is with the material or product, or the application techniques.

While poor or inadequate products often play a role, the preliminary issues of concrete preparation are probably the most common cause of failures.

Generally speaking, it is good to devote the majority of your time and effort to proper preparation. Your final job is only as good as the surface you put it on. So think...preparation, preparation, preparation.

So, 1st measure.

2nd, a thorough evaluation of existing coating and condition of concrete.

If a coating is peeling or scraping off, it is always better to get rid of it so you have a good substrate for the next step of putting a new product on the floor.

You can use chemical and water means. Applying a cleaner or stripper and washing with water, such as out of a pressure washer. Pretty messy and risks emolsifying old coating and soaking it further down into concrete. Not always a good idea.

Or mechanical means. Grinding with abrasive pads, or grinding machines. Or shot blasting.

Here are a some links with info about renting and using concrete prep equipment to give you an idea of what is possible. Using the right equipment is the key to making a seemingly impossible task--like removing failed coatings from concrete--very realistic for DIYers.

Prepare concrete surfaces for repair

Remove floor coatings with surface grinders

Info on grinding / shot blasting / concrete floor prep

More info will be posted. In the meantime, feel free to call or write for assistance with your project or answers to questions.

 

 

A floor grinder removing an old epoxy coating from a concrete floor.

This can be a virtually dustless process if done correctly by attaching a vacuum to the grinding machine. Notice hose leaving grinder. It attaches to a vacuum positioned out of the way of the work area.

NOTES ON

Acid etching, acid washing

Using a 10% Muriatic Acid wash on concrete is something most people have heard about and assume should always be done.

Not exactly.

Muriatic acid is hydrochloric acid. It often is used to open up the surface of concrete and reduce the alkalinity for coating application.

It reacts on bare concrete but does nothing to remove coatings, or contaminants from concrete.

So if you need to strip or remove a previous coating... do not bother using any acid... they will not remove coatings.

   
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