Laying concrete

[Geoffreywrc]

I've some concrete yards where the top is lifting pretty badly in some areas and other areas it's as good as first day. They were layed probably around 30 years ago.
Does any one know the reason why this happens.
The left of the picture is ok, it still has a chopped top where the right isn't. There obviously differently loads layed so must be some difference.
I'm lead to believe it is the frost causing it due to concrete being layed down to wet in the first place

 

[RAF]

What u mean lifting breaking up ?

 

[Geoffreywrc]

The top coming off it. It's not cracking cos that would mean it was put down to shallow.
I added a picture above to show the difference between 2 loads layed down at same time.

 

[Cab-over Pete]

Maybe the company made a mistake and delivered two different grades of concrete?

 

[feilding]

Salt, seen it before, drips from vehicles in winter, some mixes react very bad to salt.

 

[upnortheast]

As you suggest, Frost scale, made worse by road salt. also not helped by a wet mix with too much "slurry" on top
Air entraining addiditive in the mix is the answer. Currently spec as PAV mix