I was thinking, concrete and brick aren't used for pretty much anything, but a
merchant would want to build things of need with them, right? (both at once
since concrete is usable as a mortar substance too). Right now, one of the
clearest uses would be to build a retaining wall around a prospective
mineshaft to prevent water from flowing in, just like people do irl. There
have been many times when I've wanted to dig a shaft in a swamp or jungle,
only to be stopped by the water, and I can say I'd totally bring bricks and
concrete along with me to bypass that.
I would recommend using a 3:1 ratio of brick to concrete and for it to assign
the quantity based on how high the water level is. Thanks!