# Forum Home Renovation Fences & Screens  Special concrete for colorbond fence ??

## jiggy

My mates next door neighbour wants to replace the old shared fence with a new colorbond fence, i said i would give him a hand building it . The neighbour is paying for materials and we are supplying the labour. the neighbour says we must use a certain type of concrete for the post holes, as standard concrete will eat away at the colorbond!!! Before i tell him that he is talking through his ass, i thought that i should ask the forum cos i hate the taste of humble pie.. !!

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## Pulse

Talking through his.....  Ask him what sort of concrete, never heard that before 
cheers
Pulse

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## The Roofer

Hi jiggy,   

> as standard concrete will eat away at the colorbond

  jiggy - the only steel you can use as posts is galvanised in wet concrete - ZincAlum & Colorbond you cannot use. The colorbond fence supplier must supply posts that are galvanised (zinc coated only) as the aluminium reacts to the alkaline content of wet concrete. Zincalum & Colorbond will rust & degrade quickly if immersed in wet concrete. As far as the concrete goes - I am not aware on a special concrete that will not affect colorbond or zincalume! 
Here is the link to the BlueScope Technical Data Sheet that explains a bit more information! Maybe some of the concretors have some info on special concrete since BlueScope has no further data on this. 
N.B. I haven't heard of special concrete either Pulse! (But to double check - maybe ask in the concretors section before you tell him?)

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## Gemini

A fencer told me that you can't use the quick set  bags where you just add water (or whatever it's called ) it has to be mixed the old fashioned way. 
Cheers

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## Fenced Out

It's not April fools is it ?

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## The Roofer

> It's not April fools is it ?

  Certainly looks like it *Fenced Out* !

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## autogenous

Quick set concrete probably has calcium chloride as a cure accelerator which will rust metals, obviously galv is a bit more resistant.

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