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Topic: How to level a concrete slab with maximum height d< Next Oldest | Next Newest >
matsmith
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Posted: 04 Mar. 2017,21:57 QUOTE

Our groundworkers left us with a basement concrete slab (structural slab with rebar) which was extremely uneven. In order to progress with waterproofing this basement, we need a level floor on which to place the waterproofing system which consists of wet insulation mechanically fixed to the slab, then cavity drain membrane placed on top of that and taped to the wall membranes.

The maximum deviation is about 75mm, although a lot of this is owing to a section in the corner of about 2 sq m, so if it's possible to reduce that section then the deviation would be more like 40-45mm.

YES I know we should get the groundworkers back to sort it out. That isn't an option. That's a separate problem for me!

We plan to use a waterproof bonded screed product to level the floor. But the product is very expensive, we'd end up spending over 1500 once you factor in the bonding agent. I phoned around Ardex, Bal, Mapei, and the only guys who did a screed that would work up to 75mm that is waterproof (i.e. can sit in a wet environment) was Ardex, they recommended the A38 and E100 for bonding. The others said their product would only work up to about 50mm tops.

So I'd like to try to remove the highest section of concrete. I'm not so worried about exposing rebar as I believe the concrete was laid way too thickly over the rebar meaning we could get back at least 50mm before hitting rebar. Also there's already rebar sticking out in a few places (which will need rust treatment...) Yes I know this is not a good situation.

What type of machine, cutting discs, and tools should I use to do this? I'm guessing it involves serious dust masks.

Indeed, would it be possible?

I need to be able to lower such a machine down one storey using man power and ladders, (or it can be lowered down a big hole where a stair case and half landing will eventually be placed) as the access is limited and stairs are not yet built.
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seanandruby
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Posted: 04 Mar. 2017,22:50 QUOTE

Floor scabbler/planner. You will have to make a few passes. Cheaper make up option for floor would be a granolithic mortar mix with sbr added to existing slab after scabbling it.

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sean
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matsmith
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Posted: 04 Mar. 2017,23:00 QUOTE

Thanks. I've been looking at scabblers tonight on youtube, will hire one on Monday.

Any tips for selecting the right size scabbler? We have a 5x8m floor with internal block wall inside the room. There are a few places where the concrete goes up about 15mm in a line.

I saw ones online that leave a really uneven mess, I want to obviously make it level as possible...

After scabbling, do I just need to clean and pressure wash it, ready for bonded screed?
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seanandruby
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Posted: 04 Mar. 2017,23:25 QUOTE

Just keep going over until levelish. It makes a mess but you will learn to keep it uniform. It will need a rough finish to bond the screed to the existing floor. It amazes me how s'posed experienced contractors mess up like that  ???

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sean
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GB_Groundworks
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Posted: 05 Mar. 2017,20:53 QUOTE

its a process scabllers. then floor grinders then smaller diamond edge polishers all with heavy dust extraction

if your slab is structural and you have such variations id be concerned about rebar position and cover. sounds like they were idiots?


Edited by GB_Groundworks on 05 Mar. 2017,20:53

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Giles

Groundworks and Equestrian specialists, prestige new builds and sports pitches. High Peak, Cheshire, South Yorkshire area.

http://www.gbgroundworks.com
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