Will floor crack if I fill relief cuts?

[thejudges69]

I recently had a PPG rep at my shop to talk epoxy. He saw I had one of my relief cuts filled and mentioned that I shouldn’t do that. The cut was filled with a 2 part Euclid chemical material. He said if I fill the crack then the floor will crack elsewhere and become a mess. Any truth to this? I’m bringing in heavy trucks on this floor, 80-110k lbs so it’s seeing weight. Floor is 7-8” thick 4500 psi concrete with rebar reinforcement. You can see in the pic the one saw cut is filled prior to staining this corner.

 

[ConCretin]

Control joints are designed to hide shrinkage cracks, which occur fairly early in the curing process and don't do much after that. Filling that joint will have absolutely no effect on the floor's load bearing ability. You are fine.

Btw, if the PPG rep doesn't know any more about concrete than that, I'm not sure I'd trust what he had to say about coating it. Did he inquire about a vapor barrier? I noticed you didn't mention one. That is more of a potential concern.

 

[thejudges69]

Control joints are designed to hide shrinkage cracks, which occur fairly early in the curing process and don't do much after that. Filling that joint will have absolutely no effect on the floor's load bearing ability. You are fine.

Btw, if the PPG rep doesn't know any more about concrete than that, I'm not sure I'd trust what he had to say about coating it. Did he inquire about a vapor barrier? I noticed you didn't mention one. That is more of a potential concern.

He did inquire it has a vapor barrier below and around the perimeter except the door openings.

He said he’s seen it crack floors cause the joint can no longer flex which didn’t seem right to me since it’s epoxy and not a solid filler.

 

[JoeMcGov]

Mmmmm. I think your PPG rep needs to stick to just coatings. He's clearly not an authority on concrete.

 

[thejudges69]

Mmmmm. I think your PPG rep needs to stick to just coatings. He's clearly not an authority on concrete.

He did notice a dark corner of my shop where it maybe wicking moisture in the poured foundation

 

[Firebrick43]

Hold on a minute.

While there is no issue with the floors structure, and it wont make the control joint(as in under neath the filler) crack any more than what they originally did during curing, the soft elastomeric filler(that *MOST* use) with hard epoxy on top will definitely crack.

How could it not? Epoxy gets moderately hard and brittle and the pliable filler moves as wheels and such roll across the joint.

Now will the epoxy based crack filler that the OP used cause the surface coat of epoxy to crack???? My experience with concrete patch/fillers hasn't seen much long term sucess. But if the underlying sub base is as good as the floor sounds maybe there won't be an issue. If the relief joints were troweled in instead of being cut it wouldn't give the filler a chance in hell.

 

[thejudges69]

Hold on a minute.

While there is no issue with the floors structure, and it wont make the control joint(as in under neath the filler) crack any more than what they originally did during curing, the soft elastomeric filler(that *MOST* use) with hard epoxy on top will definitely crack.

How could it not? Epoxy gets moderately hard and brittle and the pliable filler moves as wheels and such roll across the joint.

Now will the epoxy based crack filler that the OP used cause the surface coat of epoxy to crack???? My experience with concrete patch/fillers hasn't seen much long term sucess. But if the underlying sub base is as good as the floor sounds maybe there won't be an issue. If the relief joints were troweled in instead of being cut it wouldn't give the filler a chance in hell.

I’m a little confused. So if I fill the cracks and epoxy then the concrete will crack? If I fill them and stain then they won’t?

 

[Firebrick43]

I’m a little confused. So if I fill the cracks and epoxy then the concrete will crack? If I fill them and stain then they won’t?

I am confused. Are you staining, or are you applying an epoxy coating? Why are you talking about two very different processes and if staining what does it have to do with an epoxy expert?

I don't think, at least I really hope not, that he meant that the concrete would additionally crack. I think he was talking about an epoxy placed over filled cracks, cracking(the epoxy) where the filled cracks are. That commonly happens.

If you are staining, I think you would get splotchy results in areas near the epoxy filler from it sealing the pours of the concrete, unless it was placed extremely neatly with a syringe.

 

[Professor Fate]

Use an elastomeric fill material. Done all the time.

 

[thejudges69]

I am confused. Are you staining, or are you applying an epoxy coating? Why are you talking about two very different processes and if staining what does it have to do with an epoxy expert?

I don't think, at least I really hope not, that he meant that the concrete would additionally crack. I think he was talking about an epoxy placed over filled cracks, cracking(the epoxy) where the filled cracks are. That commonly happens.

If you are staining, I think you would get splotchy results in areas near the epoxy filler from it sealing the pours of the concrete, unless it was placed extremely neatly with a syringe.

Relax cowboy im looking at both options. The epoxy guy came by to give me his opinion and thoughts and some of what he suggested didn’t seem correct so I wanted others to give theirs.

 

[LegacyIndustrial]

As LL mentioned, once cracked , initially, it is rare to see further movement.

 

[Walkers]

I think the true answer is yes, if you fill them they will crack, however, if you do not fill them they will also crack.

 

[thejudges69]

I think the true answer is yes, if you fill them they will crack, however, if you do not fill them they will also crack.

Some of the reliefs are already cracked down inside. Small cracks. He’s saying it will start to crack elsewhere along side the relief cuts

 

[Walkers]

Some of the reliefs are already cracked down inside. Small cracks. He’s saying it will start to crack elsewhere along side the relief cuts

Doubtful, most of the cracking is long done. Picture a gram cracker, putting frosting over the cracks doesn’t make it crack somewhere else.

 

[Armorpoxy]

If the slab is going to move it will still most likely fail at the joints, the filler wont 'glue them together'. PPG guy not very knowledgeable.