Is this concrete mix still good???


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Old 03-11-06, 11:05 AM
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Question Is this concrete mix still good???

Bought 24 80lb. bags of 5000PSI high early strength concrete. Unloading, I noticed that the bags are a bit stiff as if they've either been very compressed from bags on top of them or absorbed moisture and have set a little bit - don't know which. They seem to have a date on them from Nov. I had to buy it from Lowes who keeps the bags inside, but only 70 feet from the door and behind their wet lumber.

Is this any cause for concern? I need to fill in plumbing trenches cut in the basement slab and can't have any issues with a bad mix...

Thanks guys!
 
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Old 03-11-06, 12:00 PM
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Is this concrete mix still good???

Often bags of cement and pre-blended concrete get lumps. The lumps can come from compression (usually show up in the corners of the bags) or from moisture.

Open up a bag and look for lumps. All of the powdery materilas are fine. If you find lumps see if they a friable and can be broken apart. If they can be, then it is O.K.

Even a few tougher lumps are not a disaster if they were just subjected to moisture, but not enough to make "rocks". Cement requires a great deal of moisture to make concrete when added to aggregate. Cement also will continue to cure as long as it has a supply of moisture. Some lumps will break down and absorb moisture in the mixing process and become an integral part of the concrete.

If you have a lot of real hard lumps, take the bags back. It is all an amount of how many and how hard. Concrete/cement is very resiliant until it had has enough water and time, and then it become permanent.

Dick
 
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Old 03-11-06, 12:02 PM
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They are probably just compressed. You will know as soon as you open the bags. If it's powdery, it's ok. If chunky or solid, then no good. If just a small chunk here and there, toss out the chunks and use the rest. Good luck.

Pecos
 
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Old 03-11-06, 01:17 PM
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Thanks for the help guys!! I opened 1 bag and so far no real rocks. 23 to go...
 
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Old 03-11-06, 06:00 PM
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That redi-mixed stuff is always hard feeling in the bag. I roll a bag on it's side. While on the side I roll it back and forth abruptly 5- times. If it's fresh and in good shape, the agregate shakes free right away. If it's old or has been wet, it does not readily shake back to a loose powder feel.

bs5
 
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Old 03-11-06, 08:52 PM
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More than likely, it is just "packed". "Box" the bags by lifting them up a few inches and dropping them. Rotate to box all four sides. It is doubtful that a big box store would have stock long enough for moisture to set the the product in the bags.
 
 

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