Check foundation post / air bubbles

[frihopper]

Hello!

I am in the process of casting new footings UNDER a house where the footings are bad.

1. How important is it to stir with a plank or similar to prevent air bubbles? For the two footings I have cast, I haven't been able to stir with a plank, but I have shaken the tube before it set so that the air disappears and the concrete packs.

2. Alternative to a plank for stirring? Some type of telescopic tool that can be angled into the footing tube when you are under the house?

3. Is there a way to check if a footing has turned out well?

The footings are about 1.5 meters high, 19 cm in diameter, positioned on bedrock, and are reinforced with 3 rebar at 10 mm per footing in the rock with anchor compound.

 

[hempularen]

In the concrete industries, they have machines that vibrate the mold.

It's somewhat similar to you shaking the form tube.

 

[justusandersson]

Concrete that you mix yourself should be vibrated (even factory-mixed sometimes), especially when it concerns such high pilasters. Rent an electric poker vibrator from Ramirent or Cramo.

 

[jocek]

Tip: Don't Google "stavvibrator" with your work computer...

 

[frihopper]

Thank you for all the answers! Is there any way to inspect an existing plinth? For example, if there have been air bubbles in one I made recently? Remove the paper tube and check..?

 

[corre]

If you have a delta or detail sander, you can use it on the casting tube for a minute to vibrate. Even a crooked 75mm nail in the drill chuck will generate enough vibrations to vibrate a free-standing casting tube.

 

[frihopper]

If you have a delta or belt sander, you can use it on the casting pipe for a minute to vibrate.
Even a bent 75mm nail in the chuck of the drill will generate enough vibrations to vibrate a standalone casting pipe.

Thanks for the answer!

How do I go about it with a sander, do I place it against the pipe or?

I have a PSM 100 A
https://www.bosch-do-it.com/gb/en/diy/tools/psm-100-a-3165140718028-199909.jsp

How do I go about it with a bent nail and drill?

 

[corre]

Press the sanding pad against the casting pipe and run it with the grinder. No sandpaper on.

 

[rävlyan]

Can you look down the pipe with a mirror and flashlight?

 

[Stickan56]

How do I proceed with a grinder, do I put it against the pipe or?

Yes, since from what I understand you have trouble sticking something into the pipe. Do it in stages. Then maybe there are more powerful machines than yours?

Stickan

 

[frihopper]

Can you look down into the pipe with a mirror and flashlight?

On one side. But it's completely flat, basically, on the top. See a flat surface of concrete.

 

[rävlyan]

The pipes are likely directly against the rock with a small gap,
Align the pipes for center and plum, pour about 1 dm of concrete and tap the pipe so it expands slightly at the bottom and wait until the next day, then the pipes are secured at the bottom and won't move sideways.
Then it's free to fill 1 dm at a time and vibrate something against the pipe, also check if there's a little water on the top side, then the air is gone.
If you have a rod all the way up, it's probably needed for such long posts.

 

[frihopper]

Yes, because from what I understand you have trouble sticking something into the tube. Do it in rounds. Then maybe there are more powerful machines than yours?

Stickan

The procedure has been such, so far, that due to the tight space I have been scooping with a small putty knife into the tube, then after maybe half is filled, hard to say, I have shaken/wiggled the tube. Then filled up to maybe 30 cm below the house where the paper tube ends and shaken again and filled the rest. Then, quite directly after the lower paper tube is filled, I have attached the rest of the paper tube, 30 cm, and filled it and taped the upper paper tube to the lower one. I have done this in two rounds, meaning that the lower tube is maybe 120 cm and the upper is 30 cm, because it is faster to fill when I have a bit of space and also because it hasn't been possible to place the paper tube on the rebar if it went all the way up to the house.

 

[rävlyan]

You have 2 parts as you say, then you can put iron in the first piece that sticks up a bit, and then place another one that goes past the first one, there will be a seam there but it will be strong enough. Then the thing about filling 30 cm is too much, just 10 cm at a time otherwise it's difficult to remove the air and it becomes much easier to get a shake on the concrete.

 

[rävlyan]

If you have a drill with a hammer function, you can insert the largest possible bolt and vibrate against the pipe, it works well, the air escapes. Continuously check that water is coming up on top of what you've driven in, before pouring in new concrete, and no more than 10 cm at a time. It involves a lot of pouring and takes time, but just go with it and keep working.