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Hi Rick

diagnosing from a distance is always tricky ...

1) It looks like a 1:3 mix is the choice in respect to eliminating "wobble"

2) given your vibration technique -- external taping of...

hi Rick

you can't leave it like that

you have to tell us how the last column compars to the first -- surface voids, wobble, etc

Hi Rick

from this distance, I think the wobble has two sources
1) the concrete is still very green -- it will probably take another 2 weeks to develop near full strength
2) the mix used for...

Hi Rick

I won't say "looking good" till I see the surface finish on your last post :)

re flexibility, I presume you mean the posts are prone to wobble on their bases.
This is to be expected...

Hi Rick

thinking back on the big pours we did in the past, the mix had around 330kg pf cement and 150kg of fly ash per cubic metre, and a water:cement ratio of under 0.45 = less than 150 litres...

Hi Rick

as alluded to by Paul, you need enough fines in the mix to completely fill the voids between the aggregate particles.
In your case filling the voids is less about strength and mainly...

Rick

from this distance it's a little difficult to suggest much in the way of mix design

Given the small diameter of the columns, a 10mm coarse aggregate is probably where you should be looking...

I think it more likely that what caused the settlement was either air working it's way out of the form, or free water being absorbed back into the mix.


out of interest how "sloppy" was your mix

almost in the Harbour, I once joked that I was eying off the Opera House as a shed

this is not one for the faint hearted or the "she'll be right" brigade.
things to keep in mind if you go down that path
Pre-stressing needs a very strong mould (usually one made of steel) to push...

mostly :whs:

what you want to do is doable, but problematic for the unwary/inexperienced

getting a good smooth finish (no holes, no exposed agregate) off the form is dependent upon your...