Proper floor prep – Mechanical prep vs Acid washing

When it comes time to prepare a floor for a coating or resurfacing system a decision must be made as to whether to mechanically prep (grind or shot blast) or chemically prep using an acid wash.  Either way, the end result is to provide a clean, sound surface with a rough texture referred to as a concrete surface profile or CSP.

You may be tired of hearing it, but take care and wear your safety gear…eye protection, respirators, and if you are using acid to chemically prep, gloves. If acid comes in contact with your skin, immediately rinse with fresh water. Refer to the product Safety Data Sheet before using any harmful chemical.

Mechanical surface preparation of a concrete slab:

The two most common methods to mechanical prep a concrete surface are grinding and shot blasting.

Grinding requires the use of floor grinders or polishing machines that spin abrasive pads on the surface of the concrete that will remove coatings, old sealers, adhesives, as well as create a scratch pattern and rough texture to which new material can be applied.  These machines can be used wet or dry and require vacuuming of either the wet slurry or dry concrete dust created during these processes. The tooling you use on your machines will make a significant difference in the time it takes to complete your floor prep, as well as the final quality of the prepped surface. We carry a diverse selection of high-quality tooling available to get you started.

 

 

Shot blasting is a method of surface preparation that uses small beads propelled out of a machine at a high speed. The beads are shot out of the machine, striking the floor and are sucked back into the shot blaster to be reused. This “blasting” creates a sandpaper-like finish that is ideal for a strong adhesion between the existing concrete and new material. Generally, after shot blasting is done the surface is clean and ready for new material with minimal cleanup, thus making shot blasting a very cost-effective floor prep option.

 

 

Chemical Prep:

Chemical floor prep utilizes an acid to etch and burn the surface of the concrete, opening the pores of the concretes cream and creating a rough surface that is ideal for new material adhesion.  This method involves diluting the acid with water and scrubbing the solution into the slab.  The acid will “sizzle” as it reacts with the cement causing it to weaken and eventually dissolve. If muriatic acid is used it will need to be neutralized with baking soda or ammonia and rinsed thoroughly with water (commonly pressure washed). You will also need to protect all plants, grasses, and animals throughout this process. If you’re hesitant to use such a harsh chemical but do not want to sacrifice etching strength try SureCrete’s Super Concrete Renovator or SCR. SCR is an eco-friendly detergent, degreaser, and hydrochloric acid that contains no toxic heavy metals, or ozone-depleting solvents. This acid also does not need to be neutralized, can be rinsed down any drain, and can be used to earn LEED points. Click the link for more information: https://www.surecretedesign.com/product/concrete-cleaner/

 

 

Mechanical floor prep is most commonly favored over chemical for a couple of reasons.  Mechanical floor prep leaves a better surface profile which will increase adhesion between the existing slab and new material. Mechanical prep removes coatings, glues, thin set, etc. without introducing strippers or emulsifiers that may interfere with the bond between the slab and the new material.  Mechanical prep can be done dry which is better when applying coatings that are sensitive to moisture, such as epoxy.

Mechanical prep is not always possible.  There may be a texture that needs to be preserved.  In cases such as this, a chemical stripper to remove old coatings plus a chemical etch is required.  The EPA recently banned all chemicals that contain methylene chloride to be removed from manufacturing and shelves. Currently, most strippers contain this chemical.  We have a new replacement product, FAST STRIP, that is a strong emulsifier, pH neutral, stays wet, contains no solvents, and can be cleaned up with water.  FAST STRIP will remove VCT glue, carpet glue, polyurethane, polyaspartic, water-based epoxy, acrylic, and when diluted FAST STRIP can be used to remove graffiti without damaging the substrate. Emulsified materials can be scrapped up and thrown away with no special treatment. Rinse the surface thoroughly and with clean water. Click on the link for more information: https://selectsurfacesoln.com/cleaning-repair-supplies-in-orlando/

Resurfacing or coating an existing slab can be costly.  Deciding how to prep the concrete properly is the first step to having a successful outcome.  The Select Surface Team is ready and able to help you make that decision.