How to Prep Your Concrete Floor for a Cementitious Overlay

How to Prep Your Concrete Floor for a Cementitious Overlay

A cementitious overlay can turn any old concrete flooring into a shiny, clean, durable surface. Epoxy flooring offers many benefits including resistance to wear and tear, strength against chemical spills, and an impressive lifespan. If you’ve decided to add a cementitious overlay to your current cement flooring, it’s important to understand how to properly prepare the concrete base flooring.

Depending on the condition, your concrete flooring will require a variety of preparation before the cementitious overlay can be done. So, the first step in determining any problems or concerns with your existing flooring is conducting a visual examination.

A visual examination simply involves walking along the floor to note any differences or concerns with cleanliness, condition, and surface grade. You should be aware of any oily substances or dirt and debris that need to be removed prior to the epoxy coating being installed. If a weak layer of cement is found, it’s crucial that it’s removed in order for the coating to properly bond.

Additionally, it’s important to determine the moisture content and vapor transmission. This is essential in order to maintain the structural quality of the flooring base. Moisture and vapor can destroy certain polymers within polymer cement overlays and also can expand and remove top coatings.

A calcium chloride test is required in order to test for moisture within the concrete. This test can take between 60 and 72 hours, depending on the size of the area. This test produces a measurement of the pounds of vapor passing through a 1,000-square-foot area within 24 hours. Results may vary, but three pounds or less is considered safe.

Luckily, there are plenty of products on the market that can help solve any moisture problems, and an epoxy flooring contractor will be able to give you recommendations on what will work best.

Once you’ve thoroughly assessed the slab’s condition, including cracks and moisture content, and have fixed any issues, the next step is to clean. In order to have a secure bond between the concrete slab and the cementitious overlay, the slab needs to be clean and free of things like dust, oil, paint, and any other contaminants.

Depending on the level of dirtiness, your cleaning method may be as simple as vigorously scrubbing the surface and applying a commercial cleaner. After the surface is washed with a pressure washer and allowed to dry, it should be good to go.

While preparing the concrete slab may seem time-consuming, it’s a vital step in ensuring your overlay bonds well and lasts as long as possible.


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