Polyurethane is a catalyzed reaction rendering it susceptible to problems due to both moisture and temperature during application. Polyurea has a much broader application temperature range and can be installed as low as -20 degrees F. Both of these base chemistries produce a strong, abrasion resistant flexible membrane material. Spray application of these materials are widely used in waterproofing, lining and steel coating applications. The inherent flexibility and moderate chemical resistance of polyurea has made it an excellent selection as a membrane for secondary containment, mechanical equipment rooms and parking decks.
Industrial environments require modification of the system to handle more abrasive conditions. Although parking decks do not experience the same conditions as heavy industrial plant floors, some parallels can be drawn. Parking decks require a membrane material to provide crack bridging and waterproofing, as well as a wear surface that provides an impact resistant, skid-resistant, and abrasion resistant surface. Industrial applications can also utilize a membrane for crack bridging and thermal shock resistance in combination with a more durable, slip resistant wear course. Polyurea has been successfully installed in these applications using a rapid set spray applied membrane over a prepared and primed concrete substrate. Over this membrane a second application of "textured" polyurea provides a slip-resistant wear surface. As an alternative, a slow set (3 minutes) polyurea formulation can be used for applying the membrane into which an aggregate is blown in immediately after application. When using this later method, it is recommended that a polyurethane topcoat be applied to "lock" the aggregate into the system and to enhance the color stability and aesthetics of the system.
The use of polyurea spray applications in heavy industrial environments needs to address the following conditions: Initial surface repair, Crack Bridging, Control Joint filling, Expansion Joint Treatment, Heavy impact, High Traffic Wear, Oil and grease exposure, Varying chemical exposure, Thermal Shock resistance, Gouge and Tear resistance, Ability to be repaired, Short installation time. The inherent flexibility, tensile strength and abrasion resistance of polyurea cover most of these points. The potential for gouging of the elastomeric material must be addressed with a harder finish treatment. A second step application of a slow set polyurea variation or a fast set epoxy allows for the introduction of aggregate to form the skin or armor for the system.
In chemical exposure conditions it will also be necessary to apply the finish coat using the best available chemical resistant products. A Novolac epoxy, for example, may be required in high sulfuric acid conditions such as battery plants or wastewater treatment facilities. In food plants, on the other hand, a highly chemical resistant urethane finish can be specified.