The Very Idea of Someone Slashing the Bottom of the Reflecting Pool Is Ludicrous.

[lonely bird]

42. Good info

For those out there who are unfamiliar with polyurea…

It is a subset of polyurethane. Both are polyols reacted with isocyanates. A polyurea has what is called an amine terminated polyol. This amine creates a polymer that can set in seconds depending upon what other additives are used to formulate the end coating.

Polyureas used on garage floors are built to cure much more slowly. This is so they can be applied by roller or squeegee and so that flake or colored aggregate can be broadcast into the coating. Sometimes spray applied polyureas are used for industrial floor applications. The spray application is done the vast majority of the time with heated, plural component spray rigs. The material is usually heated in the drums, agitated especially if pigmented, transfer pumps then send each component to tanks that are heated higher. From there the material is pumped through heated lines to the spray gun. The two components do not mix until they are sprayed. Set times can be as fast as 3 seconds.

Aromatic polyols will generally be more chemical resistant. Aliphatic polyols will be more UV stable. They can be built to be rigid or elastomeric. Generally, the higher the elongation then the lower the chemical resistance.

Regarding water infiltration from hydrostatic pressure, if the material is well bonded it will resist the hydrostatic pressure. The load is dependent on where the water table is and how far below the water table the application is. While we don’t know what the specifications were for this project or if there even was a specification, we can ask a few questions. Was the substrate tested for moisture content prior to coating? Polyureas do not like water when being applied. Both sides can react with moisture. To get past that problem using either very fast setting materials on dry concrete or moisture tolerant primers, usually epoxies but not always, can be applied.

This whole project was done fast with, imo, little inspection and oversight.