Does dry cement have a shelf-life?
Discussion
I had some bags of cement left over from a building project last year, the La Farge Mastercrete stuff in the yellow plastic waterproof bags - it's been left outside (under cover) all winter so is about a year old at least and has sat in some sub-zero temperatures, but is still dry with no clumps - will it be good to use or will the finished strength of the mix be compromised at all?
TIA.
TIA.
With no lumps it'll be fine. If you want to improve the strength of your wall the best way to do it is to add a mesh in the mortar like this: http://www.bekaert.com/en/Product%20Catalog/Produc... any fine mesh will help, even a plastic one designed for bird protection etc. In this weather add a dash of washing up liquid and wet/soak the blocks; the blocks should be SSD - saturated, surface dry, otherwise the water in your mortar will tend to soak into the blocks rather than hydrate the cement. Good luck.
I'd get fresh, at £3 or £4 a bag it's a silly economy. It gets unpredictable, either doesn't set properly or goes nuclear (although that applies more to plaster). By all means mix it in for foundations, but not bricklaying/pointing/rendering where working time and a good set is more of an issue. It'll have a use by date on it, if it's close OK, but 6months off, forget it.
Thanks for the replies.
I'd planned to soak the blocks anyway (I've had a bad experience with ridge tiles not bonding due to them being fixed dry in really hot weather - by a so-called professional roofer!) and always tend to use a combined liquid waterproofer/plasticiser in the mortar mix.
I'm going to check the date on the bag if there is one, it's a sealed waterproof bag so I know that's helped keep it nice and moisture free inside - it's the fact it's been outside in sub-zero temperatures that worries me but then again the local builder's merchants tend to store it on under cover on pallets in their yard or unheated warehouse so what's the difference?
I'd planned to soak the blocks anyway (I've had a bad experience with ridge tiles not bonding due to them being fixed dry in really hot weather - by a so-called professional roofer!) and always tend to use a combined liquid waterproofer/plasticiser in the mortar mix.
I'm going to check the date on the bag if there is one, it's a sealed waterproof bag so I know that's helped keep it nice and moisture free inside - it's the fact it's been outside in sub-zero temperatures that worries me but then again the local builder's merchants tend to store it on under cover on pallets in their yard or unheated warehouse so what's the difference?
Gav147 said:
As JR posted it should be fine providing it is lump free. The shelf life of cement has nothing to do with it losing its physical properties it is the chemical used in it to lower the risk of dermatitis that is only good for about 6 months that gives it a "shelf life".
Yes that's what comes up first if you google LOL, but actual real life experience, fresh is best.Gav147 said:
As JR posted it should be fine providing it is lump free. The shelf life of cement has nothing to do with it losing its physical properties it is the chemical used in it to lower the risk of dermatitis that is only good for about 6 months that gives it a "shelf life".
I never knew that. Thanks 
Mr GrimNasty said:
Gav147 said:
As JR posted it should be fine providing it is lump free. The shelf life of cement has nothing to do with it losing its physical properties it is the chemical used in it to lower the risk of dermatitis that is only good for about 6 months that gives it a "shelf life".
Yes that's what comes up first if you google LOL, but actual real life experience, fresh is best.I now know however that cement actually has a use by date!
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