I was walking home the other day and came across a group of workers installing pavers for a driveway. The thing that caught my attention was one guy who was filling in the gaps (about 3/8 to 1/2 inch) between the pavers with a caulk gun loaded with a tube that contained some kind of tan material.
I've used sanded caulk before, but only indoors. I'm assuming that this is something similar, but designed for a slightly harsher environment.
What was this material, and what are the advantages and disadvantages to using this to fill the gaps between pavers?