How to level cracked outdoor slabs?

[Jacqueline23]

I am wanting to level two separate outdoor slabs. Both have some cracks and have been painted or stained in the past. I plan to paint and stencil them when they have been levelled. What are the best crack fillers, primers and levellers to use? Thank you

[MitchellMc]

Welcome to the Bunnings Workshop community @Jacqueline23. It's sensational to have you join us, and many thanks for your question about levelling a slab.

I'd recommend using Lanko 20kg 173 Floor Leveller, and the primer for it is Lanko 1L Ultraprime 124 Surface Primer. Make sure the concrete is cleaned thoroughly with a pressure washer before priming. The floor leveller with do up to 25mm thick. Remember that outdoor slabs are typically graded and sloped away from the house so water runs off them. If you level them, you could cause water to pool if they are exposed to the weather.

Regarding the slabs being previously painted, is there paint remaining on them? If so, it must be removed for the primer and floor leveller to adhere. I am unaware of a primer that will adhere to a painted surface for overcoating with a cement product.

For the cracks, you can use Gripset Betta 1L Concrete Crack Filler. However, if the cracks are fine, then the floor leveller will fill them for you. 

Please let me know if you have any questions.

Mitchell
 

[Jacqueline23]

Amazing. Thanks Mitchell. 

Yes, there is paint and what looks to be stain on the slab. Besides pressure washing is there a product that will remove the paint? There’s brand new lawn directly off the slab which I don’t want to damage with harsh chemicals. 

[MitchellMc]

There's no particularly easy way to remove paint from concrete @Jacqueline23. In some instances, it might be easiest to have the slab ground back and re-surfaced by removing material.

How badly do the slabs need to be levelled?

Mitchell

[Jacqueline23]

Quite badly unfortunately. They have been poured terribly. 

[MitchellMc]

I've done some investigating @Jacqueline23, and if it is water-based paint on the slab, then you can prime it with Sikafloor -14 prep and prime and level with Lanko 20kg 133 Pro Level Floor Leveller. However, if it is a solvent-based paint, it must be abraided and removed. To test if it is water-based, apply some methylated spirits to a rag and wipe it over the paint. If the cloth becomes stained with the paint colour, it is a water-based paint.

The Sikafloor -14 prep and prime is a somewhat specialised product and must be ordered for you through your nearest store's Special Orders team.

Mitchell

[Jacqueline23]

   

 

[Jacqueline23]

It’s a bit hard to show the significance of the uneven parts due to furniture being on it but this gives you an idea. Thanks Mitchell

[MitchellMc]

Is it the brushed concrete textured finish you are referring to @Jacqueline23?

Mitchell

[Jacqueline23]

No, but that will need a finish as well. There’s up to more than centimetre difference in some places, water pools right where the outdoor kitchen will go etc