Hot take: I think the new polymer mortar mix is a downgrade, not an upgrade.

Three years ago on a big commercial job in Phoenix, I watched a wall laid with that stuff start weeping white streaks after just one monsoon season, which never happened with the old Portland cement blend we used for decades.

3 comments

3 Comments

the_xena1mo ago

Yeah, that "weeping white streaks" thing you saw is a dead giveaway. I've seen the same sort of efflorescence bloom on brickwork way too fast with some of the new blends. It's like they're trading long-term hold for a quicker set time, and the material just doesn't breathe right or bind the same way when the weather gets mean.

jana_hart181mo ago

Maybe they're also cutting back on the water-repellent additives to save cash. That would explain why moisture moves through so easily and brings the salts out. You end up with a weak crust that crumbles after a few freeze-thaw cycles.

miles_garcia1mo ago

Oh, the "quicker set time" is the real kicker. They probably have the mix dialed in to look good for the inspector on day one, so they can get paid and move on. Who cares if it turns to salty dust in two years, right? Just another thing we get to fix later.