Concrete Pipes

CONCRETE PIPES
- Application of 100% Solids Polyurethane Coatings

An increasing number of concrete pipeline projects are being constructed through highly aggressive soils or in areas where ground water levels are high. In these hostile environments, specifying engineers are relying on high performance coatings to protect the concrete from corrosion and structural failure.

During the winter of 1989, the City of Montreal was faced with such a situation. The Public Works Department of the City was required to install a potable water pipeline next to several roadways. Not only would the ground water levels be high, but the soil surrounding the pipe would be contaminated by melting road salts. The salts, in concert with the ground water, would permeate through the concrete and attack the reinforcing steel.

Recognizing the need for a high performance coating that was economical and had a history of corrosion protection, the City chose a 100% solids polyurethane coating. It was used to protect over 15,420 feet of prestressed and pretensioned concrete pipe in diameters of 16, 20 and 24 inches.

In specifying the polyurethane coating, the City of Montreal gave consideration to the 100% solids coating's many unique performance characteristics. The coating has an adhesive strength of the concrete itself. It is very flexible and exhibits superior impact, abrasion and chemical resistance. These qualities along with an exceptionally low water vapour permeation rate ensured that the City of Montreal was getting an impervious protective barrier to prevent the infiltration of salts and water into the concrete.

As well as meeting all of the performance requirements for the project, the coating's unique handling and application characteristics allowed the applicator to coat the pipe during the coldest weeks of February.

Using a one coat multi-pass operation, the applicator sprayed the 100% solids polyurethane to achieve a minimum film build of 20 mils on the pipe. With temperatures well below freezing, the coating set up in 12 to 15 minutes. Unlike other types of coating systems, the coating cures within minutes at ambient temperatures down to -40^oF. As a result, the applicator achieved a much faster throughput and was able to meet the stringent scheduling for the project.

This website is designed by myself and hosted by Get your own Free Home Page.