# Forum Home Renovation Concreting  Pour Concrete over existing concrete

## patty6

Hi All, 
I have just spent the last 45 minutes trying to log on to this site using my old details but to no avail i used to be patty so with no success i re-registered again so im patty6 now!! 
Anyway longtime no chat I am interested to get info on pouring a concrete slab over an exisitng slab its a driveway if that helps or has anyone had success in this I think i remember reading somewhere it could be done if you drill and set starter bars in the old slab then pur over the top 
Any ideas/Experience

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## Bleedin Thumb

It has to do with the depth of concrete on the new pour. I would not attempt it under 50mm...over 75mm you wont have a problem......in between....well.... you should decrease the size of the aggregate to 10mm and increase the strength to 32mpa...but I wouldn't guarantee that it wont crack. 
If you need to top it under 50mm I would contemplate tiles....hope that helps.

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## JontyG

how about something like this:  http://www.ardexaustralia.com/produc...did=68&catid=2 
Guess it depends what you are trying to achieve.

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## PlasterPro

As has been said any less thta 75mm will be too weak, and I would also bondcrete the old concrete with atleast 2-3 coats, other wise the old slab will suck all the moisture out of new pour causing it to cure way too fast and crack more than is acceptable. :Biggrin:

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## diyclown

I am currently investigating options for my driveway also. I have for the most part a reasonably flat concrete driveway with cracks, some deep enough to twist your ankle. The Ardex product looks the goods but I will need to see if I have the gear to apply it.

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