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We are remodeling and looking to install tile flooring over concrete floors. The question we have and can’t seem to find any information is will the mortar stick to the dyed concrete floors?

For some background, we had the concrete slab dyed in 2015 and sealed. We have not had the floors resealed since and after numerous thorough cleanings over the years including bleach, should that have been enough to break the seal and allow the mortar to hold the tile to the floor? Here is a picture of what the floors currently look like.

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Thanks in advance!

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I wouldn't have concerns about the dye, particularly.

Throughly and intentionally removing all the sealer (even from the low-traffic areas) rather than depending on it having worn off adequately would be a concern. It certainly appears to still have a significant amount of sealer in parts of your picture. Bare concrete does not "shine" normally.

You might rent an industrial floor scrubber, you might acid-wash - what will work best depends on what the sealer was. Some will come right off with hot ammonia/water (do not mix different chemicals, just try one at a time and rinse well between.) Perhaps choose some low traffic areas to test different approaches to sealer removal before settling on one for the whole floor.

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  • remove concrete sealer, +1. "There are two methods for removing sealers from concrete: Mechanical [and] Chemical." - but not acid wash. E.g., "Wax Stripper, Solvent-Based Concrete Sealer Remover, Coating Stripper, Fast Strip Plus, Coating Removal, Surfkoat Nock-Off, Heavy Duty Coating Stripper." concretenetwork.com/products-sealer/remove.html - acid wash etches the concrete to provide key-in, and if it works through the sealer then you didn't need to, for tile. To epoxy coat you do need it, after you get the sealer off. But for that you really should grind it.
    – Mazura
    Commented Oct 8, 2022 at 21:02
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You can tile over the concrete as it is, as long as it is clean and free of debris and nothing is flaking or pealing off. Buy a thin set that is modified and made for the size tile you will be using. Add a latex bonding agent. The modified thin set with extra bonding agents can be pricy, but you will save the sanding, grinding, acid wash etc.

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  • The concrete was sealed in 2015 and I’m not sure if it was a water based or acrylic based sealer. Does that have not matter if I choose to use a latex bonding agent in the thin set? I will be using a large tile so I have the thin set that is for that purpose.
    – homegrown
    Commented Oct 9, 2022 at 0:44
  • It does not matter if the sealer was water based or acrylic. I would use the latex 50/50 with water to mix the thin set. Look on your bags of thin set. If it says "modified" you are all set to tile. Good Luck
    – RMDman
    Commented Oct 9, 2022 at 0:48
  • Will check it out. Thanks much for the advice
    – homegrown
    Commented Oct 9, 2022 at 0:50

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