How long does bagged cement last?

Nope, it does only have a 2/3 month life.
The dates are the usual DD/MM/YY. I found this at homebase when I bought some.

But if you want a proper quote...

"Cement is a hygroscopic material meaning that it absorbs moisture In presence of moisture it undergoes chemical reaction termed as hydration. Therefore cement remains in good condition as long as it does not come in contact with moisture. If cement is more than three months old then it should be tested for its strength before being taken into use."

So basically your cement is no good

at work we usually get lafarge cement with a shelf life of 2 months max from bagging to use,but have seen it being sold a week or so out of date and had no complaints

edit-this is blue circle paper bags iam on about,maybe mastercrete last longer,but will be a date on it somewhere

Dump It!

The amount of aggro caused by using out-of-date cement is just not worth the hassle! It NEVER mixes properly and doesn't bind. It doesn't matter what ratio you use a few months down the line you'll have to redo it.

djohn2002uk,

Been there done that, including unopened bags bought straight from the cement works, put straight into sealed drums within a dry building. - It still deteriorates in storage.

It may be OK for the odd bit of concreting where no real strength is required but I wouldn't use stored cement for anything where I want a good hardwearing bond.

For £2-£3 a bag it's still not worth the hassle.

The long answer:

The reason that cement now carries a 'manufactured on' dated and a 'use by' date is because of the Chromium (VI) Directive (2003/53/EC).

This Directive (Law) was issued in order to minimise the risk of allergic dermatitis from the use of cement.

The 2 month period is due to the use of additives in the cement to reduce the production of chromium (VI) when the cement is mixed with water. These additives become less effective with time and it is considered that after 2 months it cannot be ensured that the chromium (VI) levels would be beow 2 parts per million.

As an employee, your employer is breaking various H&S laws if you use the cement after the use by date. If you are a diy-er, it's entirely up to you, although the seller of the cement isn't allowed to sell it after the use by date either.


The shorter answer:

If the cement has been kept unopened, very dry and hasn't gone hard, it might still be OK to use, but you should always wear suitable waterproof gloves and other PPE when handling cement to prevent alkali burns and dermatitis anyway. You might think it was dry, but it might not have been dry enough.

Cement reacts with moisture and hydrates (via a series of chemical reactions which I know all about but won't bore you with!!). Once this has happened in the bag, it is useless.

The info about the 2 month thing is here:

http://www.cementindustry.co.uk/pdf/FACT%20SHEET%2010.5%20Cr%20(VI)%20-%20Formulators%20CAC.pdf