Soft concrete

[martysmarty]

Hi guys.

My builder has had to come and add some cement on top of our footings, around 50mm deep to level it off in an area.

My concern is that it was put down on monday evening, and i can still stick my finger nails in it. I also didnt like the amount of water that was sprayed on top of the mix, even going as far as cleaning the wheelbarrow out in it.

The footings are freshly pumped, that went off by the next morning and that was 6cu!

Edit: i have just been out to check it again. Its hard but its the top surface thats fingernail soft in places.

Am i expecting it to go off too quick? I always thought it would be touch hard in a day, but maybe a week before loading?

 

[johnny2007]

Did he mix the concrete on site or did he have it delivered?
Usually concrete is superficially rock hard in 24 hours.
Sprinkling cement on to is weird: did he not put enough in the mix?
If not that's a problem.

 

[martysmarty]

Hey johnny, A part of it slumped where it met a shuttering after it was pumped.

It was mixed on his yard and bought down. The bit were talking about

I can only relate it to things i have done myself and usually next day its pretty hard. I know theres a 'curing phase' if were talking full strength, but still..

I guess im a little worried because i could probably dent the top surface still if i were to poke it with a screw driver or something. If my nail will go in then surely its not really hard.

 

[^woody^]

Setting and hardening are different, the latter take days or weeks, for initial hardening and then it continues for months.

 

[martysmarty]

Hi woody. Yea, i get that. Seen it can take as long as 28 days for full strength.

My concern is the top layer being imprintable. So were talking setting yes? Could it just need more time?

 

[johnny2007]

Setting and hardening are different, the latter take days or weeks, for initial hardening and then it continues for months.

But the op can stick a finger through the outer layer after days.
Surely that's not normal, or at least all the concrete i ever used was different.

 

[^woody^]

You may well be able to poke a pointed object in or scratch it with a finger nail for a few days as the surface will be typically soft unless troweled to compact it. That's different to placing a brick or block on it which has a greater area

 

[martysmarty]

Ok, well im going to put it to the back of my mind a little then. Hopefully tonight i wont be able to mark it.

I suppose one factor could be that the footing concrete mix still has a lot of moisture rising. Maybe thats slowing it down a little.

 

[Nige F]

The Hoover dam is still curing @ the center of the concrete

 

[^woody^]

The Hoover dam is still curing @ the center of the concrete

What was wrong with it?

 

[stuart45]

Hoover should of stuck to making Vacuum cleaners.

 

[Nige F]

What was wrong with it?

Dam'ed if I know

 

[Munroast]

Did he mix the concrete on site or did he have it delivered?
Usually concrete is superficially rock hard in 24 hours.
Sprinkling cement on to is weird: did he not put enough in the mix?
If not that's a problem.

is this a trick of cowboys so as they can get the job finished quicker - rather than wait an hour or so before finishing off, sprinkle cement dust into the surface wetness then finish off - it will leave a poor surface but they will be long gone by then.

 

[martysmarty]

It wasnt cement that was sprinkled, it was a ton of water. It looked like a bath after it was done. Wheelbarrow was washed out too into it.

To me it didnt show care for keeping the water ratios right. No care at all but then i thought, i am only a keen DIYer so maybe i was missing a trick. Probably just selling it to myself!

 

[Ian H]

My hot tub base took about 4 days to fully cure, I was blaming the **** ballast I got but really I don’t know why.