I was curious about this as well.

So, I took a scrap piece and dropped it in the sink..........filled with water........and let it sit there for 90 minutes. Removed it and it's just as solid as when it went in the drink. This material is solid and well compacted!

The job is going well. Getting an entire row connected on the ends and then installing the row on the sides is much easier than doing it by individual panels...........which disengage the entire row anyway.