Cracked New Concrete

[Sharpy]

ive never seen concrete separate from over vibrating So I just presumed you’d have to go mental for separation to happen

My brother and Dad were of the mind that "if once over it is good, a couple more will be great" and wouldn't listen.....

 

[SJM]

Thanks for all the replies. Appreciate it, learning curve if nothing else.

Who was in charge of the planning ? I’d never dream of laying concrete direct onto anything other than a hardcore membrane.... if it was your decision then it’s a bit of bad luck really but if the groundswork guys told you to do that I’d expect them too answer too it tbh ... it’s just surface cracking but those cracks will hold water and gradually get worse over time

I did the design of the clamp but what we would be left with digging down was an unknown. I asked about stone groundworker said it didn’t need it as it was that hard.

What mix spec was it,
A pump mix should have more cement in it due to the slump value of it being low,
Or was it just a R 35 watered down, if you ask for more water in the mix on site, you have to sign for it, and it can , if to much water is added void the spec, and no come back on concrete suppliers
Was it a hammered down price and lower spec

Rc45 pump mix, no extra water added on site as far as I’m aware. No haggling on price and didn’t go with cheapest supplier as experience with foundations ext was this firm supplied a better product.

Looks like extreme plastic shrinkage. Should still be structural though if there’s mesh in there

When you say plastic shrinkage is that due to us covering the concrete with plastic once it had been laid?

Thanks again for all the replies

 

[RWG Contracts]

Thanks for all the replies. Appreciate it, learning curve if nothing else.



I did the design of the clamp but what we would be left with digging down was an unknown. I asked about stone groundworker said it didn’t need it as it was that hard.



Rc45 pump mix, no extra water added on site as far as I’m aware. No haggling on price and didn’t go with cheapest supplier as experience with foundations ext was this firm supplied a better product.




When you say plastic shrinkage is that due to us covering the concrete with plastic once it had been laid?

Thanks again for all the replies

plastic shrinkage is when the water evaporates from the surface of newly laid concrete

 

[kill]

ive never seen concrete separate from over vibrating So I just presumed you’d have to go mental for separation to happen

Contractors I used last year said they lent their mass walling forms to a customer who beat a vibrating poker to hard in Mass walling and all the stone went to the bottom via separation

 

[Blue.]

Contractors I used last year said they lent their mass walling forms to a customer who beat a vibrating poker to hard in Mass walling and all the stone went to the bottom via separation

would have needed to be a very wet mix for this to happen.

 

[RWG Contracts]

would have needed to be a very wet mix for this to happen.

nope. Can happen to a normal mix on a hot day in the sun

 

[RWG Contracts]

Contractors I used last year said they lent their mass walling forms to a customer who beat a vibrating poker to hard in Mass walling and all the stone went to the bottom via separation

must have gone mental cause I’ve a lad who goes wild when we’re shuttering and I’ve never seen it

 

[SJM]

So overall will this get worse over time and is there anything I can do to it? It’s a silage clamp so possible effluent

 

[HarryB97]

So overall will this get worse over time and is there anything I can do to it? It’s a silage clamp so possible effluent

Would a layer of tarmac over it help to seal the cracks as effluent is evil stuff and combine that with forklifts doing tight turns on the concrete etc

 

[RWG Contracts]

So overall will this get worse over time and is there anything I can do to it? It’s a silage clamp so possible effluent

Would a layer of tarmac over it help to seal the cracks as effluent is evil stuff and combine that with forklifts doing tight turns on the concrete etc

I’d be tempted to put a layer of tarmac over it. Or a other skin of concrete, especially as it’s for a silo. Or just leave it and if it gets worse redo the lot in 10 years

 

[SJM]

Would a layer of tarmac over it help to seal the cracks as effluent is evil stuff and combine that with forklifts doing tight turns on the concrete etc

I’d be tempted to put a layer of tarmac over it. Or a other skin of concrete, especially as it’s for a silo. Or just leave it and if it gets worse redo the lot in 10 years

We’ve done this on some old clamps a long time ago and is a much better job than just concrete. Would 25mm be enough or have to go 50mm? Could tarmac it at any stage in the future if it became a problem?

 

[aangus]

We’ve done this on some old clamps a long time ago and is a much better job than just concrete. Would 25mm be enough or have to go 50mm? Could tarmac it at any stage in the future if it became a problem?

Make sure you use asphlet at 50mm thick

 

[Forever Fendt]

Not directly. Was a plastic sheet but no stone under that as clay was very hard

why on a plastic sheet if its outside two weeks would be a very long time for plastic shrinkage cracks to appear how soon did you cut the joints after laying and how deep

 

[SJM]

To stop any chance of the clay ‘sucking’ the concrete moisture and going off too quick. Pad was laid at 150mm and saw joints done within 24hours

 

[Northeastfarmer]

No sub base in a silage clamp....
Agreed it looks like it was laid far too wet

 

[Hotbed]

Did you use air entrainer in the mix ?.

 

[Smith31]

So overall will this get worse over time and is there anything I can do to it? It’s a silage clamp so possible effluent

I had itchy hands last week, I googled the symptoms on my phone, it came back with skin cancer . In reality I only had dry skin and the wife's moisturiser cured the problem. Therefore, asking for advice on the net can lead to unnecassary worrying at times.

Whilst laying on clay is not best practice I would leave it 12 months see how it goes rather then worrying and throwing money at a non existent problem. Make sure there are no trees nearby as they will suck moisture.

 

[SJM]

Did you use air entrainer in the mix ?.

No we didn’t

 

[Blue.]

I’ve a clamp concreted direct onto clay/sand,been done near 30 years now and not a crack anywhere on it.

My main clamp however is concreted over compacted crushed concrete with visqueen used and mesh and that’s cracked.

My theory,concrete isn’t as good as it was.

 

[Lincsman]

When contractors did my shed it was a wet mix with "over sand and high cement ratio" raked level and power floated, if yours was wet enough to pump it wouldnt need a poker (unless you were filling wall shutters), I think you have separated the aggregate and all the fine stuff is at the top causing surface shrinkage due to warm weather at the time.
I think it will still be strong enough its just the acid attack it will get.

I would leave it as it is, and redo when necessary (15 years time?).. breaking up tarmac wouldnt be much fun ether, but there are 100's of grade of tarmac, like concrete, so advice would be in order.