The Brew Cabin

Posted: **Wed Aug 01, 2018 8:46 pm**

Hi all, great site you have here!!
Ok so I have an area that used to be used for parking, basically its 4â€� of compacted hardcore topped with about 3â€� of concrete, itâ€™s been solid for around 10 years.
Iâ€™m now looking to slab over it, will this base be ok?
Planning on laying slabs on a bed of mortar on top of existing concrete, the finish on the concrete is quite smooth do I need to prep the concrete to ensure the new mortar will stick to it, thinking of keying it with stone disc or does it need some sort of bond/adhesive??
Many thanks in advance

Posted: **Tue Aug 07, 2018 11:04 am**

Old concrete can have a microscopic layer of dirt on the surface that even power washing won;t shift, which is why we usually "etch" concrete with very strong hydrochloric acid before putting a new cementitious bed over it.

This may be seen as excessive for a patio, but if it's peace of mind you want, then that's the way to go. However, for me, simly priming the base with a coating of SBR or using a Slurry Primer Bond Bridge would be more than adequate.

The Brew Cabin

Laying slabs on to concrete