Slippery Rock Gazette

Bob Murrell 

M3 Technologies

Photos by Bob Murrell

Let’s say you are a stone restoration contractor and you want to branch out with some concrete work. How hard can it be, right? The project described in this article involved the removal of vinyl plank parquet wood, ceramic tile, and multiple layers of carpet adhesives, glue, and thinset. The building is the Barclay House Apartment building right in the heart of the University of Tennessee campus, in the historic Fort Sanders neighborhood, which was listed on the National Register in 1980. Both students and professionals live in this somewhat upscale urban building.

Upon arrival, the floor was an absolute mess, once the vinyl plank was removed. The client wanted the floor to have a “restoration hardware” polished look. That part would be pretty much guaranteed, as there were many divots from previous carpet tack removal and other issues, too. It would be cost prohibitive to remove all of the glues from most of these divots. So, a test was performed using a M3 Heavy Duty 20” machine, running wet, with 6 each 3-inch, 8 segment, 46 grit Magnum metal bond diamonds. Some carpet adhesive stripper and hot water was applied to help soften the many layers of glue and adhesives before running the diamonds wet. 

It was determined after testing that 3 segment 46 grit Magnums would better scrape and grind the layers of adhesives than the 8 segment, due to higher PSI on the 3 segment discs. Even so, the single disc machine was slow going, at best. So, an older HTC 500 machine was brought to the site. 220 vac power was supplied via the range receptacle. Just like with the single disc machine, the HTC would be run wet (dust could not be tolerated in the occupied building) using 40 grit single segment trapezoids (total of 9). This improved production tremendously, probably by a factor of 3-5 times.  

Left: Getting down to the concrete involved lots of scraping with razor blades. Just look at this mess!  Right: Underneath a layer of vinyl plank flooring, the concrete floor was overlaid with multiple layers of different adhesives.

Buckets of slurry, from grinding wet, had to be carried offsite for disposal.

Now, if you noticed, when I said the machine was run wet, this created another issue: wastewater disposal. Cutting concrete wet, and the coatings on top, generates quite a bit of nasty slurry. In hindsight and with an adequate dust extractor, I would suggest doing the first step or two dry, so that the waste disposal is simplified. Bags of concrete dust could be thrown into the onsite dumpster. Of course, this alternate process would need to be tested to confirm both the results and procedure. 

Now, the hardest part of this nightmare was doing the edges. The multiple layers of glue and adhesives went all the way to the wall. Remember, this is an apartment, with two bedrooms with closets, hallways, bathroom, kitchen (with appliances that must be moved out and back in), foyer with closet, and you get the idea. Unlike a large open warehouse, surface prep in a residential environment like this requires massive amounts of labor-intensive hand tool edge work. So, once the coatings on the main floor area were removed with the large planetary machine, everything from about 2 inches to the wall had to be completed by hand, before moving on to the next grit with the floor machine work.

Keep in mind that there were many holes (remember, the carpet tack removal holes) and low areas that still held adhesives. These would show up at the end as to remove these would not be cost effective at all. These low areas were here and there, especially on the bathroom floor. The areas were ground as best possible. Hence the “restoration hardware” look. 

Left: Running the HTC 500 with single segment 40 grits to remove final stubborn patches of adhesive.. Right: Floor after first burnishing with old 1500 rpm machine. Plan is to return with a 2,000 rpm machine and 3,000 dip, after construction is finished, for final polish.

AmeriPolish black dye, solvent–based stain for concrete, was chosen to achieve the effect the client wanted.

After the adhesives were removed from the floor, 50 grit resins were used to transition from the metal bond diamonds. Then the sequence was completed from 120 grit resins, 220 grit resins, and up to 400 grit resins. The edgework was taken to 120 grit just before the floor machines were run at 120 grit.

Once the floor was adequately ground with 90% of the adhesives removed, the staining process began. The client requested a black stain. The AmeriPolish Classic solvent-based penetration dye was used. It was immediately determined that the standard directions (1 bottle of dye to 1 gallon of acetone) was giving a color that was way too dark. So, the dye was double diluted at 1 bottle of dye per two gallons of acetone. This provided the look the client wanted. 

The dye was applied using a sprayer and microfiber applicator. Note: if you use a sprayer with acetone-based dye, it needs to be made for solvents. They are made with solvent-resistant materials, have special seals, and cost more than a regular sprayer. Believe me when I tell you, a regular sprayer will deteriorate and leak in a short amount of time from solvent exposure. Spend the extra amount and get one made for the job. 

Once the dye was applied as evenly and consistently as possible, it was allowed to dry for an hour or so before buffing the floor with a 3,000 grit diamond impregnated pad to remove any excess dye on the surface.

Next, it was time for the concrete guard. This was applied using a microfiber applicator. Four coats were applied, buffing with a 3,000 grit diamond impregnated pad (dip) after the second coat and final fourth coat. The final buffing was accomplished using a 1,500 rpm old burnisher with the 3,000 grit dip. It did OK, but a 2,000 or higher rpm burnisher is really needed for the best and clearest shine possible. Once the baseboards and other things were all put back and all of the other construction work was completed, it was agreed that the concrete contractor would return with the higher speed burnisher and dip to hit the floor one more time for the final pop on the gloss of the guard.

This project was a refresher course for sure! Doing surface prep in a residential setting is some of the hardest work I have seen in my 40 year career. I’m pretty sure the next concrete project will go better. Sure enough, the client has 3 more apartments in the same building, and wants them finished the same way! Oy vey..   

I always recommend doing a test area on any project to confirm both the results and procedure. Also, the best way to help ensure success is by partnering with a good distributor, like BB Industries, that knows the business. They can help with technical support, product purchase decisions, logistics, and other pertinent project information.

Bob Murrell has worked in the natural stone industry for over 40 years and is well known for his expertise in natural stone, tile, and decorative concrete restoration and maintenance. He helped develop some of the main products and processes which revolutionized the industry, and is currently the Director of Operations for M3 Technologies. Send your comments and questions to Bob at attn: publisher@slipperyrockgazette.net .