question: concrete floor has efflorescence. Want to tile the floor

[rnln]

I pulled the vinyl tiles on my bathroom floor (not the shower) and scraped off the black mastic. I spray water to avoid dust. After I am done, most of the floor dried off very quick, but there is a section of the floor is not. It has been 5 days and is still wet.

Between the dried and wet area, it seen like there is a blurry mark. I think the wet area is the area which was cut out and patched. Inside the wall, there are some water piping. This area used to have a bathroom's sink. I touched the pipes, they are dried.

There is another narrow area, which also looks wet. It is right under a wall (separate from the sink area). When I took out the moulding (base board), it wasn't wet. The wet is from the water I sprayed when I grind the floor surface.

In the pics, you see some white stuff. This white stuff start to show after several days. If I leave it alone, it'll grow taller and some will look hair-like, to maybe 1/2 inch. If I squeeze it, it's like powder. Is it called efflorescence?

Do you guys think I can put porcelain tiles on this floor? Will this stuff damage the thin-set?

[rfuerst911sc]

I'm no expert but I would think maybe wash the area with a mix of muriatic acid ?

[URY914]

Did you say "black mastic"?

[trekkor]

Find the source of the water. Broken pipe?

[Bugsinrugs]

tile and calcium cloride
Google tile and calcium cloride.http://ifti.com/guide-flooring-moisture-problems

[scottmandue]

Slab foundation? As trekkor said (our resident tile expert) looks like you may have a leaky pipe.

[sammyg2]

You can fix the leaking pipe now, or lay down new tile and then rip it back up to fix the leaking pipe.
And then lay down new tile again.

There are plumbing companies that can accurately trace underground pipes to locate the nearest ones, and determine IF they are leaking. Sounds to me like that would be $200 well spent, just for peace of mind.

[GWN7]

Originally Posted by sammyg2

You can fix the leaking pipe now, or lay down new tile and then rip it back up to fix the leaking pipe.
And then lay down new tile again.

There are plumbing companies that can accurately trace underground pipes to locate the nearest ones, and determine IF they are leaking. Sounds to me like that would be $200 well spent, just for peace of mind.

A Thermal Imaging Camera will tell you if there are any pipes in the floor.

As mentioned is this a slab home or is this a basement room?

[Porsche-O-Phile]

Originally Posted by URY914

Did you say "black mastic"?

Thinking ACM? I am.

Wonder how it was disposed of...

[look 171]

Originally Posted by Porsche-O-Phile

Thinking ACM? I am.

Wonder how it was disposed of...

I don't hear nothing. I don't see nothing.

[GH85Carrera]

What is ACM?

For sure hire someone to locate the leak and get it fixed.

[HardDrive]

Asbestos Containing Material. You need to test that stuff before taking it out. Its $35 well spent.

You either have a leaking pipe or a drainage issue. No point putting tile down over it. Shouldn't expensive to fix.

[trekkor]

Also, with that much moisture, you may have wood damage in those adjoining walls.

[rusnak]

I'd also check outside for a reverse-grade situation. Is this an exterior wall?

[Tobra]

Treat that wall for mildew/mold too

[rnln]

Wow, too many questions and suggestions. Thanks. Let me go through one by one.

This is a slab on first floor bathroom. At the wet/dark area, there was a bathroom sink. The water pipe and drain pipe were leaking above the ground level. The sink and counter were removed. The leaked pipes were fixed 4 years ago.

The whole bathroom floor has vinyl tiles. When I lift the vinyl tiles, there was black mastic type of glue that sticks the tiles to the floor. I scrape it off before grinding the concrete with diamond wheels and I did spray water while grinding to avoid dust blowing everywhere.

trekkor,
I wish I can find a way to find if there is a broken pipe in this area without cuting the concrete.

GWN7,
Do you say Thermal Imaging Camera will identify there is piping under ground, or it'll tell you if there is a leak?

Bugsinrugs,
I wonder if installing the orange membrane from Schluter Kerdi on the floor does this trick?

URY914, Porsche-O-Phile, Look171,
yes the black mastic as I described above. What are you guys saying? Am I using the wrong term? What I meant was the some kinds of glues in black color they used to stick the vinyl tile to the slab. I scraped it off with a scraper tool before grinding the concrete. Please expand your thought.
Thanks.

sammyg2,
If it is $200 to identify the leak spot under ground, it's great. Do you have contact number or any kind of phrase to search on?

trekkor, rusnak,
the other side of the wall in the pic is another room. It has laminate wood floor installed sevferal years ago. No problem right now. The laminate we ripped off didn't have problem that I could see neither .

Another wall is to the patio, there is no water nor rain to get to this wall.

The white sutff was brought to the lab testing for mold and it is not mold. Also, couple days later now, it seem to dry off itself a little more. So, I feel it is drying off very slow. If there is water leak to this concrete slab, shouldn't it be wet forever, and will not be dryed off at all? If there is not a leak, why it takes that long to dry? Are there different kinds of concrete which take longer to dry compare to other kinds of concrete?

[Porsche-O-Phile]

A lot of vinyl tiles and mastics / adhesives contain asbestos fibers. Even today (30+ years after it was banned) it's still present in certain building materials - it just has to be disclosed now (sometimes buried in the literature) so it's still out there. Prior to any demolition work - particularly of any suspected / possible ACM, testing really should be performed and if materials are found to be positive you'll need to get an industrial hygienist out there to assess the scope of abatement required. An asbestos removal contractor can then come out and abate (safely remove) the material and dispose of it legally. If you have ACM and just toss it in the trash it's a big no-no (if you get caught you can be on the hook for big fines).

You have to be really careful with these things - there are lots of cases where people have been unaware of the possible presence of these things or too cheap to remove them the right way (yes, testing, fees for industrial hygienists, abatement contractors and proper disposal cost money but it's not all that bad considering the alternative).

For your situation (residential less than four dwelling units) you're probably exempt from NESHAP but there might be other state or local rules that come into play. In any case you may have exposed yourself to a known carcinogen if you weren't wearing a respirator and just went at it and busted it up. The days of construction being an industry where guys can just show up swing away with hammers is long gone. Buildings, materials, systems, codes and potential liabilities have gotten way too complicated. You have to be really careful and know what you're doing before you can just start slamming away at things.

Be careful what you post online too.

[rnln]

Thanks Porsche-O-Phile,
I didn't know about this black glue thing but see people talk about it on the other web site all the time. Lucky, I wore mask when scraping it off and have not disposed it yet, still in my vacuum. I will search on disposing it, no problem taking it anywhere. The area is only around 3x5 feet.
Thanks again.

[GWN7]

"GWN7,
Do you say Thermal Imaging Camera will identify there is piping under ground, or it'll tell you if there is a leak?"

Yes a Thermal Imaging Camera will "look" thru the concrete and tell by the difference in the heat signature if there is a pipe imbedded in the concrete. It can also tell if the pipe is leaking.

[Bugsinrugs]

I wonder if installing the orange membrane from Schluter Kerdi on the floor does this trick?
The schluter is put down over thin set. If you are getting dampness in that area the thinset won't hold.