concrete recipes and preventing cracks.

[Piperflyer]

Is concrete placed or poured?

 

[EddieWalker]

Harvey,

Chairs are things that the rebar rests on to keep it off the ground. Some are concrete squares with wire in them to tie to the rebar, others are just good old fashion rocks. The ones I use are plastic and have a clip on the top to hold the rebar in place. You put in enough to get all the rebar off the ground and in the middle of the pad.

I've read in this thread that it's better to put the rebar in the bottom one third of the pad, and I've also read it's the top one third. I don't know which is better, but I always try to center the rebar in the pad when I pour concrete.

Here's a thread that I started a few years ago that has pictures of rebar on chairs for my house.

http://www.tractorbynet.com/forums/projects/56621-creating-workshop-home.html

Eddie

 

[RichNJKubota]

I used a small brush to finish our breezeway slab. Made swirls with the brush. Came out nice and is non-slip. Especially in the winter.

 

[Builder]

What are chairs ?

They're small wire "stands" that the rebar sits on to keep it up into the middle of the concrete. Many end up getting crushed, walked on or tipped over.

Ooops, I see eddie already explained what they are.

Here's what I mean about rebar pins and how to locate the rebar in the side of the block wall. This isn't a pad, it's footings I'm getting ready to pour in 2 days. See the 3 holes? You just make sure to pack plenty or concrete in the holes to help secure the rebar before you start the footings.



here's the front wall. 3) #5's in each trench. I just twist tie them to the vertical pins. All the pins are set to the top of the footings, so every 5-6 feet I have a set of "locator pins" to know how deep the footing concrete should be:

 

[crbr]

Could you elaborate on this please, are you saying while it is wet cut it in with one of those expansion joint groovers? Or are you saying to place what I call "expansion joint" (commercially made product that looks like creosote soaked cardboard) after a pour? (I have only seen it installed prior)

Oh, and Eddie, I always laugh about the guys telling me how they are going to "pull it up" as they go..... then they walk back across what they have "pulled up" and their boots go just as far down..

And yep, there is certainly a myriad of the little chairs and holders and what not's out there to hold the stuff in the right place.

Why I ask by the way is I am getting set (at the rate I move it may be a while ) to pour a driveway / work pad behind my house, to practice for my "shop" pour one day.

I have poured some small pads, 12 / 25 and helped on lots of big pads, but never been the lead on a big pad pour.

My opinion is to place the expansion joint in the concrete while it is freshly placed (at the time just after floating the surface. Just make sure it is hard enough to hold the joint once you tool it in. Saw cutting is an acceptable method as well but I have seen more reliable results with wet joint installation (so to speak).

I am no genius of concrete at all. I studied it in school but more so, I have worked as an Engineer on the construction of seismically designed power plants (housing nuclear reactors) and man they wanted it done correctly. So there lies my experience, good, bad or indifferent. I have seen many of craftsmen do their thing in concrete as well, all the while working on these facilities. I have worked in labs as well testing the concrete that went into the placements. No big deal, just sharing a relative point of view.

Everyone else here has good advice as well, as I take nothing away from anyone. I feel certain that there are folks here (in general) that have forgotten more than I'll ever know....

Builder, it's not nice getting your humor at others' expense .


The calcium in the cement will eat up a wire mesh in a relative short time. It will also do in rebar but that lasts a while longer (maybe a life-time ). Notice on a highway bridge project, green rebar. it is treated to resist the calcium for that reason (as well as salt).

 

[Builder]

Builder, it's not nice getting your humor at others' expense .
The calcium in the cement will eat up a wire mesh in a relative short time. It will also do in rebar but that lasts a while longer (maybe a life-time ). Notice on a highway bridge project, green rebar. it is treated to resist the calcium for that reason (as well as salt).

Yeap, we switch to green rebar in winter when calcium is added.

I've dug-up old concrete pads with wire in 'em and let me tell you, it's a world of difference compared to no wire or bar.

 

[Dargo]

Nah "builder", you get your wife and good friend to do the work. You know, as the operator, you can't get off of your machine! Look here...

 

[Builder]

Nah, "Dargo". I got people helpin' me. I'm doing this for a living, not a hobby.

BTW: Those footings are too shallow for my zone, must be down south.

 

[Dargo]

BTW: Those footings are too shallow for my zone, must be down south.

Well...actually, they are deeper than you'd think. That entire area is now filled about 36" above that current ground level. The footers were poured 24" wide X 14" deep with 4 runs of #6 rebar. The ground level is just over 3 blocks high from the top of the footers. What you don't see is the fill from digging the swimming pool plus an additional 18,000 sq. yards of dirt from digging the lake.

This picture may give you a bit better of a look. You can see where the brick ledge is and, maybe, you can see the three rows of block. I moved thousands of yards of dirt and poured just over 100 yards of concrete around the pool area in front of the pool house (which is what that footer is a picture of) The footer is a bit heavy for a pool house because it's a two story building.

 

[Builder]

I see. Didn't know you were raising the fill up higher-gotcha.

Don't work the old lady so hard, Dargo. She won't have any strength left for........awwww forget it!