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Concrete floor - How to 'merge' 2 sections - Muriatic acid?

Concrete floor - How to 'merge' 2 sections - Muriatic acid?


  #1  
Old 12-01-15, 11:10 AM
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Concrete floor - How to 'merge' 2 sections - Muriatic acid?

Hi - I have quite a large section of concrete that has been replaced due to drain replacement/bathroom addition.

I'm wondering what I need to do in order to get the different sections to 'merge' together nicely. What I mean by that is I'd like it to be as seamless as possible so both surfaces are smooth, etc.

I've been told that I should use muriatic acid on the new cement and then paint both sections the same color, but reading into muriatic acid it sounds like it's not a smart idea to use indoors, especially since the vapors can corrode metal, etc.

What other options do I have? Attached is a photo of one of the sections.

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  #2  
Old 12-01-15, 11:17 AM
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Looks fine to me. What's your end goal - to not be able to tell there's two different pours there?
 
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Old 12-03-15, 10:16 AM
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Correct, or at least get it as close as possible. I have a few questions/concerns and am not sure how to address them:

1) There is some spillover that is very rough along the edges on top of the old cement. Best way to clean this off? Scraper?

2) A few minor cracks that did not get completely filled in by the new pour. Should I fill these with caulk? If so, is it best to use a water based or polyurethane? I will probably be finishing with a water based paint if that makes a difference.

3) The new pour feels "rough" compared to the old slab. I know the old slab is painted which probably helps it feel smooth, but the other half of my basement is not painted and that whole section is very smooth. I'm guessing this was due to how I poured/finished my work. What is the best way to make it smooth so I can paint the new and old sections the same to make the transition least noticeable? This is why someone recommended the muriatic acid to me.

Thanks
 
  #4  
Old 12-03-15, 10:36 AM
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#1 - scraping would be best, muratic acid helps but I don't like to use it inside either.
#2 - Where are these cracks? up against the wall or in the middle of the floor?
#3 - Sounds like a difference in how it was finished. Will rubbing the concrete with a block smooth it or are there open pores that need filling?
 
  #5  
Old 12-04-15, 11:10 AM
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The cracks are between the new pour and the existing, so not up against a wall.

I'm attaching another pic. It's hard to see the cracks, but I think it shows the big difference in texture pretty clearly.
 
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