Polyurethane Waterproofing Systems

Liquid polyurethane waterproofing systems are coal-tar modified products. Two-component materials are catalysed curing systems, and one-component materials are cured by exposure to moisture. Both the materials exhibit comparable properties on complete curing. Two-component materials require on-site mixing of the components. One-component materials can be applied directly, but the problem with this type is polymerisation of the product inside the container if it is improperly sealed. Such products are purged with an inert gas when the pack is sealed. 

Coal tar-modified polyurethane is a cold-applied liquid waterproofing system. The system by Sonneborn is an example of this approach to waterproofing. It is applied as a liquid at the rate of 10-15 mils/coat. The coating dries hard, but has some elasticity. This material may be attacked by acids in groundwater but can be defended by a protection board. The performance of any liquid-applied waterproofing systems is limited by the capabilities of the applicator (it is difficult to achieve even coats on vertical surfaces). 

Polymer-modified asphalt is a cold-applied liquid waterproofing system. As with the Sonneborn system mentioned above, the quality of the installation depends on the applicator (it is difficult to achieve an even coating on a vertical surface). High-grade polymer-modified asphalt is superior to coal tar-modified polyurethane in elasticity, crack-spanning ability, and resealability, but inferior in its resistance to chemicals. 

Waterproof. Waterproofing barrier systems may be either hot- or cold-appHed. The hot-appHed generaUy involve a bituminous material such as asphalt used in conjunction with a reinforcing fabric such as roofing felt, cotton, or glass cloth. Cold-appHed can be bituminous or elastomeric materials either in Hquid or sheet form, with or without fabric reinforcement. Liquid elastomeric treatments include neoprene, polyurethanes, and blends of these or epoxies with bituminous materials. Among the commonly used precured elastomeric sheet materials are neoprene, polyisobutylene, EPDM mbber, and plasticized PVC. Polyethylene and PVC films and nonwoven plastic or glass fabric coated with bituminous materials also find use (78). Because these... 

Single component systems rely in most cases for the cure to take place by the reaction of moisture in the air with the prepolymer to form a solid polymer. Carbon dioxide gas is given off during this reaction and either escapes into the air or is trapped by fillers in the system. These systems are used to make waterproof barriers and single pack polyurethane paints. 

In this book I have confined discussion to those polymeric materials which are cured by chemical reaction and which have found widespread application in the construction industry. As such, the book covers materials based on epoxies, polyurethanes, silicones, polysulphides, alkyds and polyesters. In addition, there is a chapter on hybrid polymer systems and one on acrylics. It is true that acrylic emulsions are not strictly thermosetting polymer systems, but their widespread use and importance made their exclusion difficult. These materials find use as coatings, sealants, adhesives, grouts, flooring compounds, repair compounds and waterproofing agents. 

The high elasticity, low water permeability and excellent bonding make liquid polyurethane systems suitable for a wide range of waterproofing applications such as for foundations, basements, tunnels, multilevel... 

Several sections of this chapter discuss building materials (hoses and pipes, pavement, roofing, sealants, siding, and waterproofing). Here, we focus on wall materials and insulation in various extruded and molded profiles. Numerous polymers are used for these two applications. They include polystyrene, phenolic resin, polyvinylchloride, and polyurethanes for insulation purposes and polyvinylchloride, polyurethanes, and polyesters for wall systems and structural elements. The major methods of production include molding, extrusion, and pultrusion. 

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