The right flooring system means more uptime

Functional testing is the key to getting it right the first time.

By Joanne Kontorcik

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A polyurethane mortar overlay system, while not perfect for every plant, has advantages over other flooring systems in many applications. When it comes to manufacturing operations, floors get no respect.

They suffer a daily dose of foot and vehicle traffic, impacts, abrasion, thermal cycling, cracking concrete and aggressive clean-up procedures. In some facilities, the variety of spilled chemicals makes the table of contents for an encyclopedia look short and simple.

Whether interior or exterior, manufacturing exposes flooring surfaces to moisture vapor transmission, ultra violet light, and a wide range of temperatures, possibly including freeze thaw cycling.  While floors may be under constant attack, most facilities restrict allowable repair time. Downtime costs can exceed the cost of the materials and labor for the floor. If a flooring system fails to survive conditions in your plant, it must be removed and a new floor installed. More costs, more downtime.

Concrete is a well regarded and inexpensive building material. It has impressive compressive strength, but serious shortcomings as a flooring surface. These include dusting, cracking, spalling and low resistance to chemicals and wear. Concrete also stains easily and is generally considered to be unsightly.

One solution is to protect concrete with a fluid applied resin flooring system. These toppings form jointless monolithic surfaces that stop chemical penetration, eliminate dusting and, to varying degrees, protect against other forces that damage concrete. The basic resin families are epoxies, polyurethanes, polyesters, vinylesters and polyurethane mortar overlays.

Most flooring systems have an Achilles' heel. Some crack and chip. Some have marginal abrasion tolerance. Some delaminate under thermal cycling. Most resist some chemicals but deteriorate when exposed to others. Solvent based systems give off odors during installation. Multi layer systems like many epoxy overlays can require several days to install and cure fully.

Polyurethane mortar has few of these problems. It has the widest range of thermal and chemical resistance of any monolithic flooring system. It is excellent against abrasion, impact, and rapid temperature changes.

In the past thirty years, polyurethane mortar overlays have been installed around the world. The overlays show up in practically every type of manufacturing facility, from automaking to electronics manufacturing to paper processing to chemical processing to oil refineries. Aircraft hangers, kitchens, laboratories, breweries, warehousing and wet and dry food processing and storage facilities also used it.

There are millions of square feet of polyurethane mortar overlays installed in North America. It is a versatile product. In addition to floors, it sees service in containment trenches, berms, and coving as well as in re sloping floors.

But it is less well known than other systems like epoxies. One reason is that although it is readily available, polyurethane mortar overlay is patented worldwide and provided by just one manufacturer.


Impact resistance: Polyurethane mortar overlay absorbs impact by distributing it. This plastic property eliminates the chipping that more brittle flooring materials or layered systems experience.

Wear resistance: Not only does a polyurethane mortar overlay wear better than concrete, it may be better in this area than any other monolithic flooring system.

Temperature resistance: Polyurethane overlay retains its physical properties from  100 to 220 degrees Fahrenheit. As a single layer system, it withstands thermal shock. It stands up well to cleaning with steam, hot water, aggressive detergents, and disinfectants.

Chemical resistance: As mentioned earlier, polyurethane mortar overlays resist a wide range of chemicals, including acids, alkalis and solvents.  While other flooring systems may be more resistant to certain chemicals, this often comes with less abrasion and impact resistance or at a much higher cost.

For example, specially formulated epoxies are better against alkalis and Novolac vinylesters are better with solvents. Vinylesters can perform poorly under heavy vehicle traffic or other sources of physical wear.

In addition, manufacturer's guidelines for chemical resistance are only a starting point. Manufacturer's generally test their flooring systems against one chemical at a time. Most plants use a number of chemicals simultaneously, all of which inevitably end up on the floor.

When two or more chemicals mix, the combination could be bad for your floor. It is impractical for manufacturers to test each flooring system against every possible chemical combination. If you have any doubt about whether a certain system will work in your facility, install a test patch.

This touches on the basic difficulty in selecting a flooring system--balancing flooring strengths and weaknesses against chemicals and conditions in a manufacturing area. Any system that combines excellent abrasion, impact, and temperature resistance with resistance to a wide range of chemicals becomes a good choice for many applications.

Fast installation: The recommended concrete substrate preparations for any resin flooring systems is essentially the same. But once the concrete is ready, application times vary widely.

Any multi layer system, such as many epoxies, take several days to install. Then they require five to seven days of curing to reach optimum chemical resistance. On the other hand, polyurethane mortar overlays, polyesters and vinylesters cure rapidly. A repaired area can be returned to full service within 12 hours.

Multi layer polyurethane overlay can be installed in about half the time. Multi layer installations are more decorative and provide additional slip resistance when warranted.

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