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-   -   small concrete patch still very soft - howcum? (http://www.diychatroom.com/f105/small-concrete-patch-still-very-soft-howcum-161954/)

Allthunbs 11-02-2012 12:44 PM

small concrete patch still very soft - howcum?
 
Hi:

I had a pipe sticking out of the floor of my basement so I busted up the concrete around it, removed the offending section and capped the rest. The hole was a triangle less than 12" on any side I filled the section with sand and a bit of gravel up to the level of the bottom of the old concrete and filled the hole with a sand & cement mix. The bag was marked premix (premelanger) but when I mixed it, I noticed that there was no gravel. I mixed it until it was sloppy but not too wet. I sprayed the sand under the hole with a sprayer until wet. It is a day later and the concrete is still very soft. This was not a new bag of concrete but an unopened bag that I'd been storing since summer for just this job. I had done some other repairs with the same material in the summer and it hardened up in a few hours.

I can dent it with my fingers. Is this concrete too old or am I just being impatient?

concretemasonry 11-02-2012 04:26 PM

All you can do is wait. If the bag has been opened, it could have deteriorated somewhat. Even unopened, it does have a shelf life even without any holes. Eventually, it will get hard enough for such a small patch with no real load on it.

Older cement is not as reactive as fresh cement, but usually will end up OK since cement continues to gain strength for many months.

Usually sand is not considered "aggregate" for retail purposes, so you have a sand mix (with sand and cement) and not a concrete mix (with rock of some size, sand and cement).

Dick

Canarywood1 11-02-2012 05:40 PM

" I mixed it until it was sloppy but not too wet. I sprayed the sand under the hole with a sprayer until wet. It is a day later and the concrete is still very soft"


And just where did you think all that water was going to go,with no air movement,it'll probably take a week or more for it to set up.

Allthunbs 11-02-2012 09:38 PM

Thanks to you both.

It seems that patience is the key here. I was prepared to pull it all out and start again but given your comments, "patience is a virtue".

Thanks

Allthunbs

Mort 11-02-2012 10:43 PM

Yeah, you'll be fine. The hydration process takes a bit longer when the concrete is really wet.

Allthunbs 11-03-2012 05:25 AM

Thanks Mort. Boy is this internet communications stuff good!

Mort 11-04-2012 06:57 PM

I know, right? Its amazing anything got done before it came along.


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