Cracks in concrete base

garv123

Got 8m of 30N concrete poured for a 9x6m shed base yesterday.
Concrete arrived at 11am.

When I arrived home at 6 the lads who did the job were gone and the concrete was full of big cracks. They came back when I rang them and they came back for a look and said it there was nothing they could do about it because of the hot weather and strong wind that was there all day, and it was perfect when they were leaving.
They tell me that structurally the concrete is perfect and that they'll put levelling compound on top to hide the cracks.

What do people make of that option as a fix?

listermint

Best off on the construction and planning forum I would say.

Personally I would not be happy with the job. Yes it's hot but bad mix or not wetting it down . Should have been covered over too with some cloth or other material to keep the sun off.

Lumen

Is there a DPM under it?

garv123

listermint wrote: »

Best off on the construction and planning forum I would say.

Personally I would not be happy with the job. Yes it's hot but bad mix or not wetting it down . Should have been covered over too with some cloth or other material to keep the sun off.

Mix is from roadstone, I reckon they should have spent longer minding it instead of fecking off to another job. They'll charge for a full days work anyway :rolleyes:

garv123

Lumen wrote: »

Is there a DPM under it?

Yup, 1000g Polythene between the 804 and Concrete.

TimHorton

garv123 wrote: »

Got 8m of 30N concrete poured for a 9x6m shed base yesterday.
Concrete arrived at 11am.

When I arrived home at 6 the lads who did the job were gone and the concrete was full of big cracks. They came back when I rang them and they came back for a look and said it there was nothing they could do about it because of the hot weather and strong wind that was there all day, and it was perfect when they were leaving.
They tell me that structurally the concrete is perfect and that they'll put levelling compound on top to hide the cracks.

What do people make of that option as a fix?

Should have been covered - Listen to a Civil Engineer explain why https://youtu.be/DSzgFLmDsx4?t=486

Calahonda52

should have been covered with hessian and kept wet until late evening
https://www.irishconcrete.ie/wp-content/uploads/2017/01/ICF-Guidelines-for-Hot-Weather-Mar2012.pdf

ted1

They failed to follow the suppliers guidelines. I’d get them back to fix it.

https://www.roadstone.ie/wp-content/uploads/2019/10/RS-Concrete-in-Hot-Weather.pdf

Protect concrete against moisture loss during placement and particularly curing period

garv123

What is the fix? Dig it all back out?? Cracks vary from 1 to 3 inches deep. From bits I can measure. 4.5 to 5 inches deep is what the concrete is

listermint

garv123 wrote: »

What is the fix? Dig it all back out?? Cracks vary from 1 to 3 inches deep. From bits I can measure. 4.5 to 5 inches deep is what the concrete is

Pretty much. There's no fixing that tbh.

Paullimerick

It's bad alright. They didn't keep it damp and it dried and expanded too fast. Disaster now I think from what I can see.

Bonzo Delaney

Is there at least mesh steel in it as a last hope saving grace

James 007

Bonzo Delaney wrote: »

Is there at least mesh steel in it as a last hope saving grace

Yes, they should of used a hessian mat like the below & have the slab soaking wet. Practically a 5min job would of prevented the cracking
https://www.safarigroup.com.au/chemicals/hessian-curing-blanket-18oz

Most likely they will tell him there is mesh in it, without seeing them doing the job, I wouldnt trust them unless your family member saw them put it in. The next question would be was the hardcore compacted, did he witness it.

They have made the dogs dinner out of it. Whats the shed to be used for, any traffic loading. Are you restricted to now taking it all out. Could you give them the option of taking it all out & doing it again which they wont want or a better option to slab over it again or are you restricted height wise.

I wouldn't be in a rush to paying them yet.

kadman

Would have thought wetting it down and covering during the curing period was the norm
for best practice putting down concrete.

You should not have to accept this, its poor workmanship at best, useless for purpose at worst.

I would not pay until it was rectified.

NickNickleby

I wonder could you complain to Roadstone about the cracking, maybe get them to come over and say bluntly "it wasn't laid/cured properly!" then its not a layman's unqualified opinion (as the builders will likely say).

Failing that, send them a photo/video and maybe they'll respond in an email, if they're not prepared to do a site visit.

Good luck with it.

garv123

To answer a few questions at once,

The guy who did it did 2 other concrete bases for dog runs, and footpaths for me, with no issues.

He's saying there's nothing he could do to stop that happening because of the weather, and wetting it more wouldn't have helped.

He still thinks that'll be structurally sound and the levelling compound will fix it all.

There's no steel in it and the 804 was put in by a different guy doing ground works with a digger.

It's a decent made shed with proper rsj structure, not like the steel tech stuff so the shed itself would be heavy enough sitting on the edges.
I'd want to be able to back in a trailer into the shed for a lawnmower, using my l200. So maybe not far off 3t weight.

Roadstone called out today to check it out. I haven't heard any verdict yet but I doubt they'll be taking any blame.

garv123

Few more pics

Stihl waters

garv123 wrote: »

To answer a few questions at once,

There's no steel in it and the 804 was put in by a different guy doing ground works with a digger.


Roadstone called out today to check it out. I haven't heard any verdict yet but I doubt they'll be taking any blame.

No steel, wtf were they thinking putting in 8 meters without steel, I'd be very surprised if roadstone entertained that for more than 5 minutes, especially if driver added water onsite, don't pay and make them take it out or clear them

10-10-20

What depth is the slab to take that weight?
A few control-joints mightn't have gone astray either.

Stihl waters

10-10-20 wrote: »

What depth is the slab to take that weight?
A few control-joints mightn't have gone astray either.

Its working out at 150mm going by the dimensions given

kadman

Roadstone would only be responsible for delivering the correct mix, and maintaining the proper
water to cement ratio. Meaning they did not water down the mix to aid working it.

Any lack of steel or wetting down to allow a proper cure is down to the groundworks team surely.

I cant see levelling compound being a lot of use to a slab requiring structural integrity.

listermint

garv123 wrote: »

To answer a few questions at once,

The guy who did it did 2 other concrete bases for dog runs, and footpaths for me, with no issues.

He's saying there's nothing he could do to stop that happening because of the weather, and wetting it more wouldn't have helped.

He still thinks that'll be structurally sound and the levelling compound will fix it all.

There's no steel in it and the 804 was put in by a different guy doing ground works with a digger.

It's a decent made shed with proper rsj structure, not like the steel tech stuff so the shed itself would be heavy enough sitting on the edges.
I'd want to be able to back in a trailer into the shed for a lawnmower, using my l200. So maybe not far off 3t weight.

Roadstone called out today to check it out. I haven't heard any verdict yet but I doubt they'll be taking any blame.

No ****ing way would be my response.

kadman

Roadstone wont be to blame, unless you can prove the mix is faulty.
And the only way you could prove this is with a test cube of the mix.
Was this taken ?

ted1

kadman wrote: »

Roadstone wont be to blame, unless you can prove the mix is faulty.
And the only way you could prove this is with a test cube of the mix.
Was this taken ?

Roadstone can say that they stuff was laid as per their guideline. Do the op can go back to the company that did shoddy work snd then to small claims court If required

kadman

In all fairness if you intend to place a proper shed constructed of structural steelwork, then you probably
needed a proper groundworks crew that would have experience of the slab requirements for this.

There is a world of difference between foot paths and dog runs than a shed for a portal frame construction
or similar.

I guess the op knows this now, and needs a remedy for this mess . Most likely being the removal of this slab,
and replacing it with a proper one. I cant see how you can place steelwork onto the edge of a slab
with no steel in its construction.

James 007

Laying structural RSJ columns at the edges may induce further triangular cracks in the slab. I cant understand why them guys didnt put a layer of A142 mesh 2 inches from the top surface into that slab. Introducing a control joint by cutting a horizontal joint at the 4m mark when the concrete reached 2/3 of its strength would of limited the cracking & induced a control crack at this point.

It sounds to me Paddy the builder didn't want to wait around & do that either. I guess the hot weather was to blame for him skiving off to get another job done

Regarding his footpaths how did he lay it, probably in max. 3m sections, therefore no cracking.

Best you tell the wife hold onto the purse for now, that slab wont take any traffic loading. Nothing to do with Roadstone man, Paddys at fault here

kadman

If bob the builder , or Paddy worked to the instructions of the op,
then he may not be responsible either. Its gonna be a tricky one.

If it was me I would ask the builder for a digout (excuse the pun)
and remove the slab foc. And employ a proper groundworks crew that
can do a proper slab for the steel shed.

OP may have to bite the bullet on this.

Calahonda52

garv123 wrote: »

To answer a few questions at once,

The guy who did it did 2 other concrete bases for dog runs, and footpaths for me, with no issues.

He's saying there's nothing he could do to stop that happening because of the weather, and wetting it more wouldn't have helped.

He still thinks that'll be structurally sound and the levelling compound will fix it all.

There's no steel in it and the 804 was put in by a different guy doing ground works with a digger.

It's a decent made shed with proper rsj structure, not like the steel tech stuff so the shed itself would be heavy enough sitting on the edges.
I'd want to be able to back in a trailer into the shed for a lawnmower, using my l200. So maybe not far off 3t weight.

Roadstone called out today to check it out. I haven't heard any verdict yet but I doubt they'll be taking any blame.

Without mesh and a deeper strip all round as shown here
https://www.pinterest.ie/pin/501307002262214091/
it wont work.
In addition it seems the 804 was not whacked.
not covering/wetting it in the sun is negligence.

It has to come out, IMO

kadman

If your slab is carry a structural RSJ built shed, then.

You need either an engineer to spec the slab for you, and to be there before the pour,
or during it,
Or,

A groundworks team that is fully briefed and knows what is going on it, and HAS INSURANCE,
should something go wrong. As they would/should have access to their engineer.

Stihl waters

kadman wrote: »

If your slab is carry a structural RSJ built shed, then.

You need either an engineer to spec the slab for you, and to be there before the pour,
or during it,
Or,

A groundworks team that is fully briefed and knows what is going on it, and HAS INSURANCE,
should something go wrong. As they would/should have access to their engineer.

An engineer is not needed for these type of jobs, any experienced ground worker would know what to do from previous experience

kadman

Stihl waters wrote: »

An engineer is not needed for these type of jobs, any experienced ground worker would know what to do from previous experience

I said either/or, read the post:)