How to "revive" expired mortar and concrete?


Old 03-24-20, 10:09 AM
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How to "revive" expired mortar and concrete?

I have several bags of mortar and concrete about 4 years old that still look good (dry powder) and had never gotten wet. Last year I tried them, but they crumbled after drying, especially mortar, it looked like sand. Can I just add fresh cement and thus save them? What should be the ratio? Thanks.
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Old 03-24-20, 11:57 AM
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I would toss it all. It is not worth trying to save. Anything that contains Portland cement will gradually absorb moisture from the air and go bad especially once the bag has been opened.

You can't/shouldn't try to bring concrete or mortar mix back from the dead by adding more Portland. If you look at the ingredients for either nowhere does it mention a bunch of dust which is all the Portland has become after years of humidity. If you are really, really bored you could screen the stone out of the concrete mix and use them again but... it's a lot more work than it's worth.
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Old 03-24-20, 12:14 PM
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This stuff doesn't cost enough to justify the effort.
Old 03-24-20, 04:54 PM
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One the positive side - it IS useful as a really fine aggregate - something that is finer than sand and will replace stone dust. Which CAN be useful when mixing concrete or mortal.

A- Imagine putting your hand into a 5 gallon bucket which is then filled with beach sand- you can put your hand out easily.
B- Imagine putting your hand into a 5 gallon bucket which is then filled with marbles - you could pull your hand out easily.
C- BUT- putting your hand into a 5 gallon bucket which is then filled with marbles - and THEN has beach sand added. Suddenly, you CANNOT pull your hand out.

The same effect means that the old mortar and concrete WILL work as "filler" for certain mortars and concrete formulations.
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