Hello. I am currently working on my first DIY tile job; a basement bathroom that gets infrequent use. Yesterday, I tiled part of the shower curb with the same porcelain tile used on the floor, and I used the same Mapei Uncoupling Membrane mortar (an unmodified mortar) that I used with the tile over Ditra on the floor. I only used water to mix it, no additive. Now, I'm second-guessing my the thinset I used. It crumbles when it's dried and I rub it in between my fingers with water. I wanted to get some advice on if it is safe to proceed, or if I should take off those tiles on the side of the shower curb and reset using something else. The Mapei spec sheet says you should add an additive with "installations subject to water immersions, such as pools". Obviously a shower isn't immersed in water but the curb gets wet of course. The curb is a Schluter curb with ardex 8+9 applied over it (overkill, I know, but that's what I did to the whole shower since this is my first one). The thinset on the top part of the curb is no more than .5 inches thick.
Thanks in advance for taking the time to help me!
