concrete pier

[msh1]

hi all well the hole is dug i have got a 5" dia galvanised flue 4ft long that my boss donated to me that will be used as a pier filled with concrete do i pour concrete in hole and pier at same time or fill hole then wait for it to go off for a bit then fill flue what is your advise please

thanks mark

[Bizibilder]

You will need some heavy weights! If you fill the hole and the tube - both to their respective tops - gravity will ensure the tube will empty somewhat and the hole will overflow! The trick is to fill both inside and outside the tube to the level of the top of the hole and then put some planks/weights etc on top that are heavier than the concrete that will fill the rest of the pier. When all is secure fill the tube to the top. Concrete should be poured in one "go" if you want maximum strength.

(All the above assumes that the concrete can move freely between the unside and outside of the tube - which it should as you want a single lump of concrete. It may be necessary to make some large holes in the bottom end of the tube to allow this to happen.

[Tinker1947]

You might want to go down a extra 6" with the hole and bung in some rubble, broken bricks ect, give the concrete something to bite on.

[fwm891]

After you have poured your concrete keep it covered for a few days with wet sacking/cloths to prevent it drying out too quickly. If the hole your filling is dry earth dampen it and allow the dampness to penetrate for a few minutes to stop the soil absorbing the moisture from the concrete and weakening it.To fully cure your looking at about 25 days but few people leave it that long before working on it.

Good luck

[JamesF]

This year it's hard to believe that drying out too fast is a problem with concrete

What I plan to do is to make up some supports to keep the pier vertical, then pour concrete to ground level, lay some scrap chipboard with a hole cut in the centre for the pier over the top, weight that down with blocks (or possibly with the pallet forks on the tractor), insert the pier and then fill the pier.

James

[Gina]

Yes, I used a board with a round hole in it to fit the pier pipe.

[Carbon]

Actually, it you let the footing set for about an hour you'll be able to pour the pier without having to block or close up the footing. The pour will still be monolithic. Spike in a couple of long rebars to tie the pier and the footing

Any chance of getting a pipe larger than 5" in diameter? I'd hate for you to pour all that concrete and find out that your pier is prone to vibrations.

[fwm891]

Someone else had got some spiral bound ventilation tube of 200 mm (8") diam for about £15 if I remember rightly (maybe the brick pier thread)

[Steve 1962]

I'm concreting my pier next weekend (weather permitting) and we're going to try to it in one pour - so the advice about leaving it an hour is very useful - thanks!

Mine's made out of a 1.6m long 300mm diameter length of spiral air conditioning duct - it's going to end up with 600mm in the footings and 1m sticking out the top (hopefully!)

Here's some; http://www.ebay.co.uk/itm/Galvanized-Steel-Spiral-Ducting-3-0m-Hydroponics-Ventilation-Extractor-fan-/110819610063?pt=UK_Home_Garden_Hearing_Cooling_Air&var=&hash=item19cd5d0dcf

Steve

[Carbon]

Mine's made out of a 1.6m long 300mm diameter length of spiral air conditioning duct - it's going to end up with 600mm in the footings and 1m sticking out the top (hopefully!)

Steve

IMO, you should not bury the tubing into the footing. A few mm's is fine but not 600mm. The footing and pier will not be monolithic.

[JamesF]

Nice to hear your planned build is progressing Steve. Seems like an age since we discussed it when I picked up the 200P. My own is still, err, "waiting clearance for take-off".

James

[JamesF]

Oh, I have spiral aircon ducting for my pier, too. I even found a matching reducer so the top of the pier can be narrower than the rest, giving a bit more clearance.

James

[Steve 1962]

IMO, you should not bury the tubing into the footing. A few mm's is fine but not 600mm. The footing and pier will not be monolithic.

Thanks Carbon - plans being modified now!

Nice to hear your planned build is progressing Steve.

It's nice to be getting on with it James - you're right - it does seem like an age. The plan is to be complete for the end of September.

[Gina]

Everything seems to be taking an age with all this bad weather!

[msh1]

thanks for all the advise i will cut out hole in a piece of chipboard place over the tube when poured .my tube is 6" not 5" so should be ok with vibrations as i wont be anywhere near it the scope will be run from my shed about 5 mtrs away after the rain we had here yesterday the hole is full of water i think i will let it dryout for a while

mark

[Steve 1962]

Everything seems to be taking an age with all this bad weather!

Frustrating isn't it?

[oly2b]

Another method I followed given by builder is to cut a 3" length of your tube and cast a spigot proud of your foundation with rebar set in the foundation block and ready to tie the tube to the foundation. Next day remove the 3" peice of tube align your pier tube and fill.

This gives a location for your pier vertical which is tied to the lower foundation.