Bare concrete floors not only have a past, they now have a brighter future. Finished concrete floors without coverings or coatings are becoming more and more polular for two reasons: first, new products and techniques that improve its finished appearance; and second, dollars and cents.

Do you dare to go bare?
- Philip Smith, P.E., FACI, ASTM

Costing a typical vinyl floor covering
Consider that a bare, hardened concrete floor has a very long life cycle (normally lasting 30 years or more) and requires comparatively little maintenance. Vinyl floor coverings, on the other hand, require continual expenditures on maintenance and normally have a much shorter useful life expectancy of ten years or less.

Let's compare some actual costs and projections based on estimates provided by the National Terrazzo Institute and recent issues of Concrete Construction magazine. The average initial cost of vinyl composition tile (VCT) for a 10,000 square foot floor is approximately $1.50 per square foot, or $15,000. Annual maintenance costs stemming from nightly mopping, regular wax maintenance, removal and replacement are estimated to add no less than $1.00 per square foot per year. That makes the total per year maintenance costs in this example at least $10,000. If this floor is like so many others, within ten years the old VCT will be removed and replaced at a cost of approximately $25,000, or $2.50 per square foot. At that time, the normal maintenance cycle (and its costs) begins again.

In contrast, the initial installed cost to chemically harden and densify a new concrete floor is approximately $.30 per square foot, or $3,000 for a 10,000 square foot floor. Installation of our chemical hardener and densifier, L&M SEAL HARD, is normally a single, one-time cost for the total 30-year life cycle of the floor. In worst case situations on floors that experience high volume of traffic, it can be repeated between 10 and 20 years with minimum preparation. Hardened concrete floors do not need to be waxed to look good, but they do benefit from a regular schedule of washing with mild cleaner/conditioners and water. Cleaning frequency depends upon the conditions and activity of the facility. Annual costs to maintain a chemically hardened floor range from $.25 to $.50 per square foot. In our example, this would equal a total annual upkeep cost of no more than $5,000.

Using a life cycle of 30 years, in this example the total cost of a VCT floor is approximately $ 375,000. For a SEAL HARD floor it would be approximately $153,000. By selecting a SEAL HARD floor instead of VCT, the savings on a relatively small, 10,000 square foot floor over 30 years would be nearly a quarter-million dollars!

Factor in the size of larger floor areas and it reminds you of what Senator Everett Dirksen once said: "A billon here and a billon there, and after a while it becomes real money." Well, the senator was right. It is real money! No wonder many national retail chains are rushing to change over vinyl composition floors to this low cost alternative.

Now that you know the why, let me give you the how.
New Concrete:
In recent years the concrete industry has introduced new equipment and techniques for placing and finishing concrete that make it shine like highly polished marble. The surface of a concrete floor can be chemically hardened and sealed days (or even weeks) after the placement of the concrete. This chemical process produces a concrete surface that polishes and resists wear. It is very durable. With the passage of time, a well-maintained hardened concrete surface takes on and keeps an attractive, durable sheen, requiring minimal maintenance effort and cost.

How does this happen? Fresh concrete becomes a hardened mass through a process known as hydration. Hydration is the chemical reaction between water and Portland cement. During hydration, calcium silicate hydrate (CSH) is produced. CSH is the crystalline formation that gives cement paste its strength, durability and abrasion resistance.

Hydration also produces calcium hydroxide, a hydration by-product also commonly known as "free lime." Free lime is a comparatively soft, weak material. Calcium carbonate, another bad actor, also occurs in concrete over time as a result of carbonation. Both calcium hydroxide and calcium carbonate deteriorate easily and detract from the long-term durability of concrete. Unlike CSH, their presence in concrete is undesirable.

All concrete surfaces contain varying amounts of microscopic particles of free lime and calcium carbonate. As concrete wears, these microscopic, soft particles yield to abrasion and leave what are known as "micro-pits." Over time, micro-pits erode into increasingly larger areas, in much the same way that a small pothole in a highway becomes larger.

So what's the answer? Chemically convert the microscopic soft particles into very hard CSH. Then the concrete surface will be uniformly hardened so micro-pitting is greatly diminished. Treated surfaces become more uniformly hard, and under the influence of normal use will now instead resist wear and become polished.

L&M's SEAL HARD does just this. This chemical hardener and densifier chemically reacts with weak calcium hydroxide and calcium carbonate compounds in the concrete surface to form beneficial calcium silicate hydrate (CSH), contributing to a concrete floor's long-term durability. The CSH produced by the SEAL HARD's chemical reaction with calcium compounds produces essentially the same beneficial crystal formation that is produced by proper hydration of Portland cement.

As a result, SEAL HARD has been proven over the years to be an effective and low cost way to protect new concrete floors.

It's never too late to have a bare concrete floor!
Old Concrete:
Today, you can improve the appearance and functionality of concrete surfaces after the fact. Our FGS PermaShine process does just that. It restores worn out concrete floors to an aesthetically pleasing and very functional work platform. FGS PermaShine floors will yield many additional years of service and require only minimal maintenance.

Preparation steps of the FGS PermaShine system remove some of the old surface on the concrete floor by diamond grinding, quickly removing floor coverings or coatings, including vinyl composition tile, epoxy and urethane coatings, leaving a bare concrete surface. These steps also remove micro-pitted sections, and level uneven surface elevations.

Once the bare concrete surface is exposed the polishing steps begin, bringing the floor to a luster ranging from low to a very high shine, depending upon the desired use and appearance of the floor. During a meeting with the owner a sample area may be prepared. At this time the degree of luster and the amount of aggregate that may be exposed during the grinding process are determined. This allows the owner to quickly see what the finished floor will look like. (Typically, they're impressed. Very impressed.)

Historically, diamond grinding and polishing of concrete floors has been performed as a wet process. With recent improvements in dry, dust-free procedures, L&M has adopted a patented dry process. The wet grinding process, which has its historical roots in terrazzo floor installation, creates a messy, mud-like slurry residue on the surface of the floor. This slurry is difficult to remove and may interfere with operational activities in adjacent areas.

The dry process, on the other hand, is much cleaner. With the use of high performance vacuum equipment, our FGS PermaShine process eliminates virtually all airborne dust caused by the grinding or polishing steps. In addition, there is virtually no impact on adjacent work areas. Stock does not have to be removed from shelves. Customers and workmen can even remain in areas adjacent to the area being polished. Floor downtime is also greatly reduced. In approximately an hour after completion, your floor is ready to be returned to full service.

As Paul Harvey might say, "Now, for the rest of the story!"
Once the concrete floor has been polished to the desired luster level under the FGS PermaShine process, the surface is then chemically hardened and densified. This is a crucial step. If this step is omitted or improperly executed, the polished shine will soon disappear. The floor will begin to show wear again, and the investment in upgrading your floor will soon become only a memory. Chemically hardening and densifying a polished concrete surface is an important step designed to restore the original hard finish provided when it was installed with a tight, hard-troweled concrete surface.

A tightly-troweled floor is a floor that has been physically hardened. During the troweling process the microscopic particles of hydrating cement are actually pushed closer together. By having the particles of cement physically closer together as the cement hydrates, the CSH crystals will also be closer to each other once hydration is complete. Troweling increases concrete's surface durability and strength, but only in the area that is referred to as the near surface wear zone (normally a depth of 1/8 to 1/4 inch). Over time, with use and then during the grinding and polishing process, this top wear zone surface is partially removed, exposing less dense, lower strength concrete underneath.

After the visually transforming steps of grinding and polishing are completed, the surface of the floor, while appearing very shiny, is also very open and porous.

In order to protect the surface of a newly polished concrete floor, it must be chemically hardened. L&M's product, FGS Hardener Plus, hardens polished concrete in the same way as SEAL HARD. It chemically reacts with calcium hydroxide and calcium carbonate to form strong, durable calcium silicate hydrate (CSH). Over time this chemical process essentially provides the same end result as hard troweling by enriching the surface of the concrete with CSH crystals.

It is worth noting again that CSH is the crystalline formation that gives concrete its strength and wear resistance. FGS PermaShine does that better than any other process on the market as it, in effect, chemically restores lost hardened cement paste removed during the grinding process. This means longer term performance of your newly restored concrete floor.

Now back to the original question: "Do you dare to go to bare concrete floors?" As the facts become clearer, we find that more and more owners and designers are answering this question with an enthusiastic "Yes!" They're finding that chemically hardened and densified concrete floors are an attractive, low-cost alternative to other floor coverings and coatings.

My recommendation? Try SEAL HARD on your new concrete floors, or FGS PermaShine on your older, worn floors. You and your bottom line are going to love it.

— Philip Smith, P.E., FACI, ASTM; L&M Vice President, Technical Director, Resident Engineer Phone: 800-362-3331, e-mail: philsmith@lmcc.com.

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