Hi guys, While my scope is in Meade Hospital receiving specialist care and maybe a heart transplant, I want to pour a concrete pier to mount the ol' girl on for her home coming.
The idea is to fill a deep hole in the ground with concrete and continue upward inside a 'formatube' cylinder about 12" dia (30cm).
What I don't want:
is the concrete to be pushed out the bottom by the weight of the column of concrete in the tube.
I will have 3 x 1'" screwed shafts embedded into the concrete to take the base plate and this I don't want to move, yet the base plate will be in the way of pouring if I have it in place .
Sooo any tips, advice, is much needed and will be greatly valued.
Doug, try cutting a triangle of ply as a template instead of using the base plate. Cut a triangular hole out of that triangle (The whole lot could be square if you wanted to, it would just be easier to make the template if it had a bolt hole at each apex). Now you can fix your bolts at the right spot in the triangular ply and still be able to pour concrete through the center of the template.
If you have enough "formatube"...try placing another 20 cm below ground..( I used a couple of plastic buckets with the bottom cut out and the tops screwed facing each other)..be sure the top of the "formatube" is level before and after filling with concrete.
Use gladwrap to protect the tops of the screwed shafts.
Cheers!
Thanks Paul, that should solve one of my concerns. I picked up an offcut of particle board and can use the base piece as a template for the holes.
rgs,
Doug
Quote:
Originally Posted by [1ponders]
Doug, try cutting a triangle of ply as a template instead of using the base plate. Cut a triangular hole out of that triangle (The whole lot could be square if you wanted to, it would just be easier to make the template if it had a bolt hole at each apex). Now you can fix your bolts at the right spot in the triangular ply and still be able to pour concrete through the center of the template.
That is a very good idea, I'll do it!
thanks.
rgs,
Doug
Quote:
Originally Posted by astro_nutt
If you have enough "formatube"...try placing another 20 cm below ground..( I used a couple of plastic buckets with the bottom cut out and the tops screwed facing each other)..be sure the top of the "formatube" is level before and after filling with concrete.
Use gladwrap to protect the tops of the screwed shafts.
Cheers!
Doug,
From my understanding, you want to pour a footing in the ground, and then continue up with a short column, at the top of which there will be 3 bolts for your base plate. My suggestion would be to do this in 2 stages. Excavate and pour the footing first, and embed 3 x 12mm starter bars 600mm long into the footing, so that they are exposed by 300mm. (ie 300mm in, and 300mm out of the concrete) Cut a piece of your formatube approximately 75mm long, and set that on the top of your footing, and fill that at the same time. The next day, cut away the 75mm collar of formatube. You will then be left with a stub column 75 mm high that will act as a starter for the next stage, and will prevent concrete from spilling out. Slip the formatube over the stub, and ensure that it is plumb by using a spirit level on 2 faces, at 90 degrees to each other. Brace the tube well. Fill with concrete, and fit off your bolts at the top with the template of your particle board. However, make quite sure that the particle board is HMR board (highly moisture resistent, it shoud have a greenish tinge on the cut edges), if it isn't the template will disintegrate when it gets wet. Use a wettish concrete to make sure it compacts well, but don't make it too sloppy. When you have finished the concreting, ensure you check the tube again for plumb. You will need 170kg of raw materials per metre length of 300 diameter formatube, plus of course what you use in the ground.
G'day Mike, xcuse the delay in replying.
I have had alternate advice from a different source and so I have been cogitating. (my head hurts)
The alternate advice was to have the formatube go pretty much right to the bottom of the excavation and just leave it there.....period.
Mike I'm going to run with your advice (I like it), but I am a little unsure of pouring fresh concrete on to (even day) old concrete.
Would it be wise to put a layer of 'bondcrete' on top of the pier stub prior to finishing the pier part ? Also, I had a browse through Bunnings yesterday and the only things I saw that looked like they were meant to go into concrete to anchor were like large staples made out of about 8mm twisted steel. They were also heavily rusted which I think is not good.
Another question, do you think there would there be any gain in placing the 75mm starter tube about 12-16mm above the general footing level to allow a fillet to form, reducung the risk/tendancy for cracking?
Doug,
There will be no problem at all in pouring your fresh concrete onto day old concrete. Roughen up the top of the starter, make sure it's clean from dust and loose particles, and if you like, mix up a half litre of cement/water slurry to a creamy consistancy, and brush that on just before you pour the new concrete. Bondcrete can be used, but if you have some PVA glue, use that instead, it's much the same stuff. The steel starter bars will give you all the strength you need at the joint. Buy a 1.8m length of 12 mm Booker rod (Threaded rod) and cut it into 3 pieces for your starters. Alternatively, and this would be best, have your rods go from top to bottom of the pier and footing. Pour the footing, and then push the rods down into the wet concrete. As booker rod is sometimes greasy, clean it with metho, or petrol, soapy water etc, as oil is a release agent, and oily steel will not stick to concrete. I shall PM you with a sketch of what I suggest.
Here is my sketch showing what I would recommend for a really steady pier that would support pretty well anything. The only reason I have suggested 300 dia formatube is because that was what Doug originally said he was using, but 200 would be adequate. I would not suggest running the formatube down to the bottom of the excavation under any circumstances, as over time the cardboard will either rot away, be eaten by termites, or otherwise dissolve, and then the column will be loose in the ground. Not what you want! If it is the intention to concrete a slab around the column, or to put a timber deck around it, make sure that you leave a 12 mm gap all around the pier, so that vibrations are not transferred to the pier.
If you have any questions, or want to have a copy of the sketch emailed to you, PM me with your contact details, and I shall send it on.
This hasn't come out quite as I intended, as it will only print at about 300%. I'm not sure what I have done that I shouldn't, but as I say, if you want further details, PM me.
Mike thanks for the sketch. The Image size is a bit big is all. I saved it and resized it to 640 x 480 pixels (it was 2482 x 3508 pixels). At the new size it fits an A4 nicely.
best,
Doug
Quote:
Originally Posted by Sharnbrook
This hasn't come out quite as I intended, as it will only print at about 300%. I'm not sure what I have done that I shouldn't, but as I say, if you want further details, PM me.
Concreting for dummies
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