Concrete Chairs

[EddieWalker]

One of the things I look for in pictures and videos of people pouring concrete, is if they use concrete chairs to hold the rebar off of the ground. If they are not using them, that's a huge red flag to me. The same thing if they are using wire instead of rebar, that's a red flag.

While watching some YouTube videos last night, it hit me that 100% of every commercial concrete job that I saw, they use Concrete Chairs.

The only people that do not use them are residential jobs, or home owners doing their own pours. To me, biggest lie told in concrete work is that they will pull it up while spreading it, and it will remain in the middle of the slab after being walked on.

 

[Chewwy]

One of the things I look for in pictures and videos of people pouring concrete, is if they use concrete chairs to hold the rebar off of the ground. If they are not using them, that's a huge red flag to me. The same thing if they are using wire instead of rebar, that's a red flag.

While watching some YouTube videos last night, it hit me that 100% of every commercial concrete job that I saw, they use Concrete Chairs.

The only people that do not use them are residential jobs, or home owners doing their own pours. To me, biggest lie told in concrete work is that they will pull it up while spreading it, and it will remain in the middle of the slab after being walked on.

A lot of residential work today (driveways and parking areas) involves using fiberglass reinforcement in lieu of either rebar or wire. Seems to be pretty standard in our area anyway.

 

[two_bit_score]

The same thing if they are using wire instead of rebar, that's a red flag.

I can see using wire on a sidewalk. I bet many residential sidewalks dont have it.

Everything else should have rebar. Do you prefer steel wire chairs or plastic?

 

[lilranch2001]

I find those chairs very difficult to sit on

 

[grsthegreat]

I always use steel chairs and rebar. Does not matter, cracks anyways.

 

[geblackwell]

One of the things I look for in pictures and videos of people pouring concrete, is if they use concrete chairs to hold the rebar off of the ground. If they are not using them, that's a huge red flag to me. The same thing if they are using wire instead of rebar, that's a red flag.

While watching some YouTube videos last night, it hit me that 100% of every commercial concrete job that I saw, they use Concrete Chairs.

The only people that do not use them are residential jobs, or home owners doing their own pours. To me, biggest lie told in concrete work is that they will pull it up while spreading it, and it will remain in the middle of the slab after being walked on.

Take a look at Concrete with the Hauses on youtube. Sometimes they do, sometimes not. They usually explain why or why not. They do pull the rebar if not on chairs. He is the concrete guy that everyone uses in that area (your go to guy.)
Perhaps in commercial there is an inspector on the job and they can not pour without it.
Seems like fiber rebar is the new thing.

 

[EddieWalker]

Take a look at Concrete with the Hauses on youtube. Sometimes they do, sometimes not. They usually explain why or why not. They do pull the rebar if not on chairs. He is the concrete guy that everyone uses in that area (your go to guy.)
Perhaps in commercial there is an inspector on the job and they can not pour without it.
Seems like fiber rebar is the new thing.

I just looked at their page and skimmed through 4 different videos of driveways that they poured. The good thing about them is how dry their mix is. It has great slump. They also do a nice job of finish work.

But I would never hire them because of they short cuts they are taking with rebar and wire. They didn't even lay out the rebar in a grid before pouring the concrete in one video. One guy was tossing rebar sticks into the concrete as it was being spread, just sort of spacing them by where they landed. Then they covered them up as they spread the concrete. None of it was tied together, and none of them where spaced evenly. That really shocked me. I've never seen anybody do that before!!!! Then the other driveways they had wire laying on the gravel. There was one guy with a hammer that bent over and hooked the wire, but it didn't come up, and a second later, they walked over it while spreading the concrete. 100% useless, but an excellent example of what not to do.

 

[EddieWalker]

Concrete cracks because of the water leaving the concrete as it cures. The more water that's added to the mix, the bigger the cracks. Another good example of commercial concrete jobs being better then residential is the amount of water that's used. In commercial jobs, they test it with a slump bucket, and sometimes, they take samples and let them cure, then put them through a press to measure how much strength it has. Nobody doing a driveway is testing their concrete, and sadly, almost everybody has concrete that isn't as strong as they paid for because of the amount of water added.

Fiber helps deal with the cracking from water, but it does not replace rebar. If you used fiber and didn't use rebar, and your concrete didn't crack, it's because they didn't add extra water. The fiber is only good for tiny, hairline cracks. They still happen, but the fiber holds the cracks together better so it's harder to see them.

Wire is great for walkways because nobody is walking on it. You just have to make sure it's in the middle to lower 1/3 of the pad. With walkways, it's easy to work the concrete and not walk on it. Walking on wire is why wire should never be used on anything wider then a walkway. It always gets pushed to the bottom of the concrete.

100% of every house that I've cut open the concrete slab of to relocated drain lines that has had cracks in the slab, also had wire at the bottom of the slab. I've never seen concrete issues where the rebar was in the middle of the slab.

 

[lilranch2001]

Concrete cracks because of the water leaving the concrete as it cures. The more water that's added to the mix, the bigger the cracks. Another good example of commercial concrete jobs being better then residential is the amount of water that's used. In commercial jobs, they test it with a slump bucket, and sometimes, they take samples and let them cure, then put them through a press to measure how much strength it has. Nobody doing a driveway is testing their concrete, and sadly, almost everybody has concrete that isn't as strong as they paid for because of the amount of water added.

Fiber helps deal with the cracking from water, but it does not replace rebar. If you used fiber and didn't use rebar, and your concrete didn't crack, it's because they didn't add extra water. The fiber is only good for tiny, hairline cracks. They still happen, but the fiber holds the cracks together better so it's harder to see them.

Wire is great for walkways because nobody is walking on it. You just have to make sure it's in the middle to lower 1/3 of the pad. With walkways, it's easy to work the concrete and not walk on it. Walking on wire is why wire should never be used on anything wider then a walkway. It always gets pushed to the bottom of the concrete.

100% of every house that I've cut open the concrete slab of to relocated drain lines that has had cracks in the slab, also had wife at the bottom of the slab. I've never seen concrete issues where the rebar was in the middle of the slab.

I hope “wife at the bottom of the slab” is a typo…..

 

[scootr]

I find whatever you use to suspend the reinforcement the bar or wire must be pulled up.
Step on a chair and it sinks down and stays down 99% of the time.
Fiber is okay. Fiber reinforced concrete still cracks and can move up or down on one side of the crack.
Rebar adds significantly more strength and tends to restrict vertical movement when cracked.
#10 wire mesh 6 o.c. is pretty stout - it's a good alternative for most small jobs.
Judging from 35 yrs of placing concrete from residential, multifamily, and govt work