Crumbling cement floor in workshop

[pe2dave]

Cheapskate builders, the concrete floor is crumbling. Sealed and painted, recurs where foot traffic.

How good are the 'expensive' Rust-oleum epoxy products? Worth it?
Any idea how to get better adhesion to existing concrete please?
I've about 10 small areas, with poor edging (could be made deeper).

 

[Bingy man]

You probably won’t like my advice- tbh I wouldn’t want to hear this myself if in a similar situation however- imo there is no need for expensive products but repairs to several areas suggests that other areas will eventually break up and then you are back to square one . Remove any loose areas and dust , completely hoover / sweep floor , treat with a good sealer eg SBR and allow to dry , repeat the SBR if in any doubt-now for what you probably won’t want to hear -screed the complete floor area with a good strong mix 3-1 sharp sand /cement and bigger job than you anticipated but once done it’s done . Years ago there was a product called I believe ( granno flex) tiny bits of granite which when mixed with screed would be rock hard but I don’t think you can get these days . I give this advice because patching up poor concrete doesn’t usually last . I’m pretty sure there is a similar product available and I’ll have a look.btw pictures of the damage will help you get the best advice.

 

[Bingy man]

This was a product I was considering for a similar job but the customer went via the insurance route in the end but is similar to granno flex - hope it helps you out .

 

[pe2dave]

You probably won’t like my advice- tbh I wouldn’t want to hear this myself if in a similar situation however- imo there is no need for expensive products but repairs to several areas suggests that other areas will eventually break up and then you are back to square one .

Agreed, but my case quite impractical. I attempted a cheap solution, and have garage paint adhering nicely to 98% of the floor. Secondly, have a look round your workshop, have you the space (and energy) to clear it out for 4 days? I don't.
Thanks though.

 

[niall Y]

Cheapskate builders, the concrete floor is crumbling. Sealed and painted, recurs where foot traffic.

How good are the 'expensive' Rust-oleum epoxy products? Worth it?
Any idea how to get better adhesion to existing concrete please?
I've about 10 small areas, with poor edging (could be made deeper).

 

[pe2dave]

@niall Y Yes, that's what I said...?

 

[niall Y]

OOPS......... sorry about that. A case of sausage fingers!

I have this selfsame problem. I can't blame the builders, however, as my son and I laid the screed. My ( at the time ) teenage, son was on the mixer ,Bless him - his heart wasn't in the job.

Screwfix used to sell an epoxy cement for patching.. You get a pack of washed sand and two-part epoxy to mix together.The maintenance staff where I used to work used it to make-good the factory floors when removing and replacing machinery. It's what I will use - when I get round to it.

 

[Bingy man]

Agreed, but my case quite impractical. I attempted a cheap solution, and have garage paint adhering nicely to 98% of the floor. Secondly, have a look round your workshop, have you the space (and energy) to clear it out for 4 days? I don't.
Thanks though.

I knew it would be difficult and possibly unworkable but it would be a complete and permanent repair- so if that’s the case cut out the offending areas as deep as possible and use either screed or fine aggregate to fill in, once dry use your paint to complete the job .

 

[Sandyn]

There's a possibility they over tamped concrete which was too wet, bringing too much water to the surface. It could just be the surface layer which is soft in some areas. Could you do a test area using one of these to remove the soft stuff on the top. It might give you more information about the state of the slab.

 

[Limey Lurker]

Cement needs to cure BEFORE it dries. If it was poured in weather like that of the past few weeks (at least, in the South), there is a good chance that it is, in places, un-cured. because it dried first. IIWY, I would wet, until it will absorb no more, a powdery area with water: there is a chance that the curing process will resume, and a day later the surface will be cohesive.

 

[pe2dave]

Youtube video makes sense (apart from dealing with the rusty rebar).
'Patching cement'? A good option?
@niall Y I couldn't find epoxy cement on Screwfix. Anyone?

 

[johna.clements]

Cement needs to cure BEFORE it dries. If it was poured in weather like that of the past few weeks (at least, in the South), there is a good chance that it is, in places, un-cured. because it dried first. IIWY, I would wet, until it will absorb no more, a powdery area with water: there is a chance that the curing process will resume, and a day later the surface will be cohesive.

For the highest strength you want the concrete to remain damp as long as possible.

When mixing concrete you want it to have as low a water cement ratio to be workable, it starts to get difficult to place if the water is less than half the cement. If there is too much water the cement particles bond to the water rather than each other. On the surface the cement particles will be become dust because they are insufficiently bonded.

Once the concrete has set the the cement particles that have not encountered any water need some water to form a bond. You can cover the concrete to keep off the wind and sun and stop the surface drying too quickly and becoming dusty and weaker. There are also curing compounds that you can spray on concrete as soon as it is finished to keep the water in but covering it is as good. If you wet the set concrete you will add water that will find its way inside to the missed cement particles. Properly cured concrete will be in the order of 10% stronger more at the surface.

Painting concrete that has set and is visibly dry would help with curing. The pva would help to seal in the water so more water would go to the cement and would also add more water. The pva will rub off where trafficked and will come off if it is reactivated by water.

 

[pe2dave]

Purchased Everbuild Jetcem Rapid Repair Cement, I'll (try to remember) to let you know
what it's like after a year.

 

[johna.clements]

Youtube video makes sense (apart from dealing with the rusty rebar).
'Patching cement'? A good option?
@niall Y I couldn't find epoxy cement on Screwfix. Anyone?

The rusty rebar was the cause of the blown concrete, rust expands. I would have wire brushed the rebar, whilst wearing eye protection, to remove most of the rust. The rebar does not have enough cover to protect it from water.

The feather edge (sloping edge) to the hole may not be a good idea. Where the material runs out to nothing the sand filler in the mix end up exposed and above the surface. The cement mixture will not be able to surround it and bond properly to the entire particle and so be weaker. It would be better to cut a vertical edge, maybe 5mm or so for this product (what ever the instructions are), so that the filler can be completely surrounded.

 

[pe2dave]

The feather edge (sloping edge) to the hole may not be a good idea. Where the material runs out to nothing the sand filler in the mix end up exposed and above the surface. The cement mixture will not be able to surround it and bond properly to the entire particle and so be weaker. It would be better to cut a vertical edge, maybe 5mm or so for this product (what ever the instructions are), so that the filler can be completely surrounded.

Good point. Angle grinder, diamond edge.

 

[niall Y]

Youtube video makes sense (apart from dealing with the rusty rebar).
'Patching cement'? A good option?
@niall Y I couldn't find epoxy cement on Screwfix. Anyone?

Ah yes.... they seem to have stopped selling that, It was good stuff. I glued and repaired a lot of York stone treads with it a few years back.
Nearest equivalent I've found is Resincoat Deep Fill Epoxy Mortar - though I note you have gone for a rapid set cement
. I'd be interested to see how you get on with that as it is a lot cheaper option.

 

[pe2dave]

- though I note you have gone for a rapid set cement
. I'd be interested to see how you get on with that as it is a lot cheaper option.

<grin/> I'm not a Yorkshireman for nothing!

 

[clogs]

A German company thats based in France "Weber" but worldwide....
www.ukweber make products just for that job as well as screed and cement plaster's....Render.....
they have an excellent websight and are happy to talk over the phone....
I'm just a happy customer....

 

[pe2dave]

A German company thats based in France "Weber" but worldwide....
www.ukweber make products just for that job as well as screed and cement plaster's....Render.....
they have an excellent websight and are happy to talk over the phone....
I'm just a happy customer....

Bad link @clogs ?

 

[Sideways]

If you need to fill holes, the lads in the factory always used car body filler - isopon or whatever - to patch holes when castings got dropped on concrete. It sticks better and doesn't disintegrate the way small / thin patches of concrete do.