Pegs in concrete

[trevorbayliss]

I have just watched a video on tube showing some new foundations for an extension.

They guy was a builder and had pegs every meter to help him level the concrete. He just used a rake to level up and tamp down and the pegs were his main guide. It seems pretty simple.

I did the same thing this week but used a thick length of rebar cut up and hammered into the ground. The concrete goes in on friday, but BC said the wood was a no no and the rebar will slowly suck up moisture and then corrode over the years.

Is my rebar a bad idea ? I have also marked a line around my boards to give me my level, but would like to use the rebar guide as well. What do others do to get a level ?

 

[stuart45]

Ask him what's happened to all the rebar that's gone into concrete over the years.

 

[trevorbayliss]

Yes that was what i was thinking, but i suppose rebar sits in the trench and isn't punctured into it and so drawing moisture up from the ground. This was his concern, but is it really an issue. I asked about the wood i had seen used in the video and i think he knew it is a common thing to do but said they should be removed after level is sorted. But really how many builders remove these pegs ?

So you think my rebar is ok to use ?

 

[stuart45]

Wood and rebar have been used for years to peg out on site, and I can't remember any come backs from it. I know in theory it could be taken out later, but it normally stays in. The alkali content in concrete protects the steel from rusting and moisture can rise into the concrete without the rebar going into the ground anyway.
Nowadays a lot of footings are trench filled so the pegs go into the wall of the foundation, not the bottom.

 

[trevorbayliss]

Ok all makes sense and i will leave my rebar in place.

 

[^woody^]

They guy was a builder and had pegs

He's a fraud.

 

[trevorbayliss]

This is the link and he has a fair few building vids. I can see why wood is not a good thing to have in the foundations, but rebar should be ok. What do you think about the rebar woody ?

 

[stuart45]

If it's only about 9 inches of concrete going in I would stick the pegs in the bottom of the trench, but when trench filling I would stick the rebar in the sides of the trench horizontally as you dont need such long pegs, the concrete does not push them when it flows in, they are easy to see as you level along side them and you don't have a problem taking them out to reuse.

 

[stuart45]

http://www.contractortalk.com/attachments/f90/44798d1300703798-deep-footings-phpu7raujam.jpg

Here's an example of the sides pegged out with a deep trench fill.

 

[^woody^]

What do you think about the rebar woody ?

In the real world, a bit of (slim) timber, a bamboo cane or rebar is not going to make the slightest bit of difference to the strength of concrete strip.

 

[trevorbayliss]

Got the concrete in this morning. Took the rebar out and screwed some screws in the ply wood around the level line i had drawn.

All gone well with no excess. Concrete pretty much levelled itself really. Lots of prodding with the rake etc and used my length of wood.

Got a gen 3 mix of concrete. Would a gen 1 have been ok though ?

Also when can you take off the ply casing ? Can i do it the next day ?

 

[John D v2.0]

Can't imagine the mix would make Any difference for a normal house foundation as long as it's got cement in it. But it's in now anyway! Not sure about taking the ply off, personally I would leave it longer but it's not exactly going to crack even after overnight, unless you start putting loads on it.

 

[JohnD]

for a day or two it will be quite weak, and striking shuttering or walking on it may damage it. You can still scratch your name in it with a nail.

concrete gains strength all the time it is kept wet, and stops as soon as it dries. Foundation concrete usually doesn't dry out, but if you spray the top surface and cover it with plastic sheet, that will help the top drying out in this sunny weather. It will change from grey to near-white if it dries.

28 days is a reasonable period for concrete to cure, and further improvement will be slight, and increasingly slow (although it will continue strengthening for a century or more if kept wet).

 

[trevorbayliss]

Well i will need to get the shuttering off on monday so i can reuse it for section two of the foundations.

This afternoon i have noticed the neighbours drive has broken a little around the area the wagon was stood. It is a triangle shape about 20cm in diameter and it is 100mm concrete drive. What normally happens in these cases where the drive has been damaged ?

 

[John D v2.0]

John are you sure about 28 days, that seems extremely long! Our builders pretty much had the roof on by that time, and the SE didn't bat an eyelid.

And regarding damage caused by your contractors to the neighbours property, just talk to them and keep them happy/repair whatever. If there's any issue, in theory they can claim the money back off you in court but obviously that's not going to be ideal for anyone.
You might be able to in turn claim off the contractor, but they don't have to live next door to you so might not be as helpful.