Concrete Posts.

[beppington]

Lloyd- What about digging your fence post hole & then set a single form atop the hole, so the post is completed & already sitting right where you want it when you remove the form?

You could plumb the form & support it with angled braces to the ground.

This way you'd never have to move the posts anywhere, & the concrete below grade would fill the nooks & crannies of the post hole, also requiring no tamping.

Obviously this would be a lot different than the multi-post form method you're using now, but maybe do-able?

 

[RDrancher]

If you built the form so it could be taken apart, say remove the ends, and then the first part of the side form. Remove the first post. Then remove the next form separator, and continue till the base was empty.

This is the way you should be doing it Lloyd. With screws of course.

Here are a few more tips that I utilize when casting countertops. If you build the bottom, dividers and sides from 3/4-in.-thick melamine-coated particleboard, they will be a breeze to strip and eliminate the need for form oil. Even though my countertops are much thinner than your posts (as thin as 1") using a pea gravel mix will make things much easier. I would also add fibers for strength and a liquid acrylic additive (plasticizer) to cut down on the amount of water needed to keep the mix workable.

John

 

[RobertBrown]

This is the way you should be doing it Lloyd. With screws of course.

Here are a few more tips that I utilize when casting countertops. If you build the bottom, dividers and sides from 3/4-in.-thick melamine-coated particleboard, they will be a breeze to strip and eliminate the need for form oil. Even though my countertops are much thinner than your posts (as thin as 1") using a pea gravel mix will make things much easier. I would also add fibers for strength and a liquid acrylic additive (plasticizer) to cut down on the amount of water needed to keep the mix workable.

John

It sounds good, but can you tell us what those materials are going to do to the costs?
It sounds expensive, how many times can this form be used? How much does plastisizer cost and how much do you have to buy?

I have used a product that is available in bags at the H.I. center. It's called "surface bonding concrete". It has no stones or gravel just fibers (presumably fiberglass?). If I remember correctly it's mix 5000psi mix. It's a lot more expensive than bagged concrete and the bags are only 40#.

 

[Egon]

Particle board used outside in the Nova Scotia climate may not survive long.

A little extra Portland may do as well as other type of additives and be cheaper

Pretty straight forward form shape. With a zero slump mix shouldn't need plasticisers.

Note: working with old-old data.