Concrete shower floor
I am rebuilding the shower stall in our master bathroom and need some advice for pouring and curing a concrete shower floor.
I used a 40 mil pvc membrane to form a pan and poured the shower floor using "sackrete".
Seven days later( this morning), I ran my hand over the concrete to check and see if the floor was dry and had cured enough to continue work. However, when I rub the floor.....the cement (dust) seems to come up out of the floor.Is that normal? I am afraid to continue work--- since this shower is up stairs and over my dining room--
I want to be certain the floor is good. My intent is to apply ceramic tile over the concrete but I am not sure it is safe to continue.
Did I use the correct product for a poured concrete shower floor ? The aggregate in the "sackrete" seemed to be a large size for a smooth floor. Can I use a premix mortar ?
Can I use a concrete sealer (water proofing) like "damtite" over the cured concrete- to ensure no leaks thru the concrete to the 40 mil pvc membrane? Will the grout (for ceramic tile) stick to the sealer?
I appreciate any help and advice you can offer.
I'm not a concrete expert but have built many shower bases like your project (they are the best)- so I'll try to help.
Can't understand the concrete problem after seven days - should certainly be cured enough by now. Did you "play" with it too long? If so, the cement content of the mix may have come to the surface and can in fact be "dusted off". The base is probably ok but if you are doubtful about the finish (is it too "rough"?) you can use regular mortar mix to smooth it out. It has been proven that when applying a thin smoothing coat over existing concrete, a coating of "white glue" helps to bond the new mix to the old.
As for the sealer, I never use this, at least at this stage. I think that with your PVC membrane, concrete, ceramic tile and grout, the chance of water seepage is probably non-existant. However, as a belt and braces precaution, I usually give the finished base a good coat of silicon sealer (available in stores for this specific purpose).
Incidentally, although they are not as readilly available these days for some reason, I like to use 1"x1" mosiac tiles - they "mold" to the base contours very well.
Hope this helps and good luck. Alan