Not sure what went wrong here, have I used the wrong type of concrete ? 1

[MiniMe4Eng]

These are pictures for a small project, replacing a bath tub with a shower and changing the position
Short story: it is not drying out and I am wondering if the pipe/joins cracked when the concrete cured or
it is because of using the wrong type of concrete and too much water.
I poured the concrete (both types, see below) on March 29!!

Here is what is under concrete

Here is before pouring concrete

Here is within a week since I poured the concrete

And here is the situation as of yesterday

This is the concrete used for the now dried out area

And since I wrongly estimated how much I needed I used some left over concrete from a fence project
This concrete mix was used for the area that is not drying up after so long and I am wondering what is going on
It is true that the mix for the area that still looks wet was poured a little too liquid
For that type of concrete and for such a small patch should it take this long to cure ?

 

[MiniMe4Eng]

No the concrete was mixed in a bucket, clean, no dirt there, maybe some leftovers from the previous bag (see the pictures)
this concrete mix bag (a half of a bag), was a leftover that sat for 2-3 years in my garage, not sure if this matters


I am not really concerned about those patches collapsing on the gravel that is underneath as this will be under a very sturdy shower base that does not bend even a mm under my 115Kilos weight (tall guy)
I will wait longer for this to cure to see if the color turns grey and it looks dry
Rushing to pour the self leveling concrete now while this patch is still wet does not make much sense as it is just a small portion of the bathroom floor
It is more important for me to make sure I have no problems in that area...so I will wait

 

[phamENG]

this concrete mix bag (a half of a bag), was a leftover that sat for 2-3 years in my garage, not sure if this matters

It matters very much. Most garages are not climate controlled, so if the humidity ever got very high it could have started hydrating some of the cement in the mix, though it could still look viable on first inspection. I have a few bags left over from a fence project from a few years ago, also in my garage. The city frowns on disposing of old bags of concrete in the trash, and my truck is broken, so there they sit. Last month I tried to make a little "slab" that my son could break with a new toy (RC excavator with jackhammer attachment). It did exactly nothing. After a week it just a pile of damp sand, gravel, and itty-bitty pieces of hydrated cement.

 

[MiniMe4Eng]

It matters very much. Most garages are not climate controlled, so if the humidity ever got very high it could have started hydrating some of the cement in the mix, though it could still look viable on first inspection. I have a few bags left over from a fence project from a few years ago, also in my garage. The city frowns on disposing of old bags of concrete in the trash, and my truck is broken, so there they sit. Last month I tried to make a little "slab" that my son could break with a new toy (RC excavator with jackhammer attachment). It did exactly nothing. After a week it just a pile of damp sand, gravel, and itty-bitty pieces of hydrated cement

Doesn't seem to be my case, the patch is rock solid

 

[BridgeSmith]

the patch is rock solid

Then there's no problem; it's just as it should be. Again, if your concern is putting a cement-based material over it, you shouldn't be concerned. Concrete can be, and is, poured underwater, and as long as it's not disturbed, it cures just fine.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[phamENG]

"Solid" isn't exactly a technical term when it comes to concrete. Just because it has hardened doesn't mean that it isn't excessively porous and prone to wicking water, or especially strong (though strength isn't critical here). When you broke out the slab, was there a vapor barrier below it? If not, have you had issues with elevated moisture in that room before? You clearly have issues with ground water coming up close to grade - I live in a swamp so I get it. In the middle of a drought I can hit water less than 12" below grade. I'd strongly suggest doing some work on the exterior (grading, in-ground drainage, etc.) to move ground water away from your house. And if you had a vapor barrier before, you should have patched it when you put this back. If you have a nice, warm, dry interior and wet soil underneath, that moisture will migrate through the slab, mortar, etc. and into the living space, potentially damaging your flooring along the way.

 

[MiniMe4Eng]

There was no humidity barrier ther just the concrete. It was even worse than this before, whoever qorked that bathroom effectively left open dirt under the bath tub. I had no issues with extending the openning by hitting the edges of it woth a hammer and the concrete chipped away little by little in a quite cintrolled way.
The house was built in 1960....they did not use to install a barrier back then
The basement has elevated humidity in the summer but I think it is normal. I can keep it under 50% with a dehumidifier that runs every 3h for 1h. That is summer time only...no problems in the winter
The house at the bottom end of a street that goes up on a hill, not very sloped, that could be the only issue here. The grading around the house is fine and on that side I have a patio that is sloped away from the house.

 

[MiniMe4Eng]

Two months later it is almost dried up

 

[The Concrete Cure Toowoomba]

I would assume most of the initial problems stemmed from the large amount of water pooling in the area below the concrete. Sounds like it was just there temporarily though, and it looks like it has dried up now. Great tips and concreting advice from everyone above. Good learnings.
Ashton from The Concrete Cure Toowoomba