Concrete formwork

Having trouble uploading photos but I thought I would share my new test pergola. This one has an 800 mm high square base which will reduce the sway in the posts. Also the posts are closer at 1.5 m centres. I reverted to standard gravel and sand mix 3:1 gravel:cement. I used a mechanical vibrator in the posts and in the base. One thing I overlooked was to tie down the base. What happened to the first one is that the concrete lifted the formwork up off the foundation. This oversight was easily fixed with the remaining posts. There is a photo of the first pergola as it is now and the work in progress on the new one. There are more air pockets in these posts, probably because, as I said, I reverted back to standard gravel instead of the fine stuff but it could also be because I used the mechanical vibrator and did not tap the concrete as often when I placed it in the PVC pipe.
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I know we come from the land down under but can us locals get a photo that we can relate to?

I am enjoying building the third and main pergola. I estimate that I have laid 100 cubic metres of concrete in my handyman life but this has been the ultimate in learning about this fantastic, malleable material. The mould I bought from America was stated to last 16 pours. I have made over 30 and have about 16 more to go so hope it lasts the distance.
Beside the practice/test pergolas I have made lots of tests columns and moulds.
There will be just under 9 ton of concrete in this pergola if I build the cross bars from concrete which I am seriously considering. I will then be able to curve the arches.
I have been very worried about lining up all the columns but am very pleased so far.
It is a great project both physically and mentally.
Mini-orb has been used form the columns.
I can't post the pictures properly. Sorry.

Hi rick_rine,
i spent 30 odd years making molds
statues column's retaining walls fountains pots
all out of concrete i used fibreglass to make the outer casting.
iv worked for BGC concrete in
perth for 12 months before getting sick of that.
ideally you want the thickest concrete possible
and use a plasticizer, this is an additive to make
your concrete go from 30 slump to 100 slump the additive last for about 15/20 min so you need to work fast
before the concrete returns to 30 slump or what ever it was before adding plasticizer, we used it all the time for tilt up walls were high strength was needed. The less water you add to concrete the less shrinkage you'll get.

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The columns have been made with mini orb and look great. In the columns I used 10 mm reinforcmnt and a 4-1 gravel cement mix. In the beams I have used nylon fibres and two six mm reinforcment bars. It has been over two years in planning but looks amazing. Mostly mixed by hand. Poured in-situ. Almost perfectly straight and level surprise. I am using 4 concreting gravel, 3 bickies sand, and two cement for the crossbeams. They are 3 metres long with a span between the posts of two metres, they are .1 wide and 0.14 high. The supporting beams are 0.1 x 0.18. The posts are on a 0.3 x 0.3 base with 0.15 diameter columns moulded with mini orb. No scaffolding was needed as they sat up right and I poured the concrete in with a garden pot.

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The he pergola is twelve metres long, two metres wide, has 18 columns and has taken six months about so far to build. I am thinking of a clematis or wisteria. I got the idea when I was in Italy a few years ago. One of a kind! No one else would have one of these in their backyard, and probably no one else would want one either 😃

Rick

Seeing those columns immediately made me think Appian Way and Aqueducts. It looks extremely impressive!

An amazing project.

Regards
Paul