Concrete Shuttering/Formwork

[MKUltraBorg]

Hi all,

I have just replaced 7 wooden fence posts with concrete ones. The base of the removed posts sit in a strip of concrete that meets and is 5cm above my neighbours block paved front garden.

As I had to break some of the concrete to remove the posts I now want to reform it. I know this means timber form work.

I have a couple of questions...

1. What do I put on the timber to stop the concrete sticking to it when it sets?

2. How can I prevent concreting my neighbours block paving? Was thinking polythene on it, then my form work on top to meet the upright edge that I want to face off.

3. I have 2 bags of postfix left over...can I use this for minor form work? Talking no more than 5cm on any aspect.

Any anyone who's recently been digging out and breaking old posts...respect to ya! My achey arms!!

Thanks

 

[JohnD]

not sure I understand. Can you post some pics?

When I do wooden shuttering, it loosens (by shrinking as it dries out) after the concrete has set. A tap with a hammer usually frees it if stuck. Wooden forms in the ground will rot harmlessly away.

 

[MKUltraBorg]

Thanks for the reply John, have uploaded a pic which for context is taken from our side of the fence showing the broken concrete strip which sits higher than our neighbours lovely block paving. Basically I don't want to get concrete on his drive and leave a mess. Was thinking that any residue would likely brush off but how do I stop it leaking from underneath my timber form?

Cheers!
Simon

 

[JohnD]

I think I'd remove all the cracked and broken material, and loose earth, probably excavate a little deeper for more strength, build a box out of boards, supporting on the outside with spikes driven into the ground. Put sticky tape on the neighbours paving, then paper as padding, them a piece of ply or carpet so you can walk round the post while working.

I'd use a hand-mix not postcrete, it has a longer working life. Lay it in layers, tamping each layer down well. Let most of it slump (it will) before you add the final layer.

the top you can smooth off with a rectangular trowel. Use the trowel to give it a tiny slope towards your garden so rain and mud don't run onto his paving. You can use a stiff brush to give the surface texture while still wet.

once you have an initial set, a couple of hours, you can uncover the neighbours side to check for spills. If any, brush away dry. If you try to clean it wet, the cement will leave stains, and the water may erode the surface of your new slab.

use a dry brush on your neighbours paving to brush away any drips or splashes. On a sunny day, it will dry before it has time to gain strength. Cover over your new slab to keep it wet for several days, preferably a week or more, because it will continue gaining hardness and strength while it is wet.

Covering it will also prevent animal footprints.

Your new concrete will look bright and clean. After a week, rub it with wet mud to stain it to match the rest.

If you can lay your hands on some stiff thin material, such as metal, hardboard or thin ply, you may be able to tap it down any gap between the paving and your slab, to prevent seepage. You may be unable to remove it afterwards.

 

[MKUltraBorg]

John, thanks loads for the comprehensive reply, much appreciated. Sounds just the job, a solid base with a clean edge and a happy neighbour!

Will post pics of the finished job.