You obviously can't. Anyone else can, just by the feel. It goes crunchy when partly hydrated. So use a little more..the rest has just turned into an expensive sand..;-)
All cement does is top the sand grains moving around. All the sand does is stop the aggregate moving around.
If this was a prestressed concrete beam holding up a nuclear shelter, I'd be worried. For fence posts in the ground? heck you can set them in pure fresh soil rammed down...
can't bear to be wrong, can you?
I've never seen a warranty on a new bag of cement either.
On the contrary, I have studied cement and concrete technology over quite a few years. My work has involved concrete mix designs, strength and durability testing.
Bull.
By that stage, it is very far gone. Cement will lose up to half its strength without you ever being able to feel it.
Complete nonsense. The cement/water paste acts as an adhesive, coating the fine and coarse aggregate to hold the whole mix together, and giving the whole mix its fundamental strength.
You really do talk so much rubbish.
Without the hydrated cement, it could do no such thing.
So, plonk! And goodbye.
er. that's actually a perfect way of saying exactly what I said.
? oh dear. Yu do have problems with understanding te physics of adhesives and fillers.
Fine by me.
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course it does, it tells you if it sets like rock or not. The only downside if you'd have to wait a few days to see if reasonable strength is building up.
But Adam said its been a few months in the lounge, so no worries there! You can keep cement a few years in dry storage and it still sets hard.
NT
so for setting fence posts, no problem whatsoever. End of issue.
NT
look like bare blocks some ghastly fake marks in plain rendering? No can't be that some blocks are a differnt colour.
Waste of a fiver and trip to get it. Your just out of date stuff would have been fine for setting a post provided it was still a powder.
OK, lets state the obvious:
The reality is cement stores years _if_ stored in good conditions, and if you dont mind 3:1 giving you the result of a less hard mix.
NT
Even if it has lost 90% of its strength, it still feels as though "it sets like rock".
You just don't know, and anyone who claims they do is telling porkies.
A room with 50% - 70% humidity is NOT dry storage. And as I pointed out above, cement that appears to you to be "setting hard" can have lost as much as 90% of its strength. Furthermore, its capacity for watertightness will be severely affected.
Cement is not that expensive, certainly not worth taking this sort of a risk on. Except if you don't know what you are talking about, so please feel free go ahead and use the stale stuff, as you will be none the wiser. ;-)
A close up for you.
I will use the old stuff for the path. It is still powder. The trip was not wasted as I needed a new spirt level.
Adam
either it sets like rock or it doesnt. If it does, it does its job of setting like rock. That may not be good enough spec for bridge building, but for setting posts its more than enough.
A lounge with 70% RH would be unusual, and not one to put cement in.
Some of us here have done, and it works fine for undemanding apps. Those of us that have tried it know that.
NT
On the contrary, in a slightly moist atmosphere, each cement particle can hydrate (in other words, go off) without joining up to other particles to form lumps. I have been involved in investigating several projects where such degradation of cement caused major problems, including complete collapse of a major structure.
The idea that cement is perfectly OK to use as long as there are no lumps in it is an old wives' tale.
NO, its called a sauna or a hothouse.
Wont accept your talking bollocks, will you?
Bollocks. I have left bags in 'slightly moist atmospheres' for the odd year, and I an assure you they set into a lump.
I don't think fence posts are 'major structures'.
No one is denying that teh cement aint as good, but your theoretical attitude is totally at odds with the average DIY persons direct experience.
No, its a sound piece of experiental knowledge. It is OK to use, and I have even used it WITH lumps in, breaking them up.
The mortar was not as good, but it was good enough for the purpose at the time.
I have also eaten food more than one microsecond past its sell by date, and haven't died in agony either.
If you knew as much about cement as you would have us believe, you would also know that is degradation begins the moment it leaves the milling stage and is bagged, and is uniform, and progressive, and the rate depends on the moisture resistance of the plastic lined sack, and the amount of moisture in the air, neither of which are guaranteed to be in any way constants.
The time stamp on the bag is a guide that ensures that even in the worst of cases the unopened cement should still be to spec at that date. Given better storeage cement last far longer than that, and anyne who has actually used it knows that it degrades through clearly identifiable stages, the first being a slight crust that forms on the outside of the stuff, where the moisture has penetrated first. Then you get clumping where there has been generalised partial hydration and there isn't much in the way of powder left. Nevertheless that lumps if they can be broken down, still have about 50% ability to rehydrate, and doubling up on the cement ratio will result in usable mixtures for non demanding applications.
Which 99.99% of D-I-Y mortars are. Certainly adequate for path laying. fence posts and non critical above ground bricklaying.
If you knew anything about concrete, you would also know that teh strength is poor in tension, which is why we use rebar, and good in compression, and is MAINLY down to the actual aggregate in use. The finction of the cement is not to provide strength as such, but to prevent the aggregates from shearing past one another.
Most cement failures are due to porisoity, and freszing or ingress of aor+water to reinfirced structres leading to rusting of te reinfircement.
The point about porosity is the only one you have made that I consider valid: old cement as I pointed out may not have enough 'good stuff' in it to totally fill the interstices in the sand, and therefore become akin to a weaker more porous screed type material. If that is used in serious structures without compensating in any way there will indeed be trouble.
However serious structures of that nature are either precast in a factory, or cast using readymix. I have yet to see a bridge made from bags of DIY cement on site mixed in a barrow or portable mixer ;-)
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lol. I'm not sure he's yet noticed that bedding fence posts doesnt need any cement at all. Your explanations are spot on Mr Philosopher
rest snipped
I've dealt with enough genuinely qualified 'experts' to not be susprised if Bruce really were who he says. Its remarkable what blcks passes for expertise, how much such people too often assume, and how comically wrong they get things, too often over and over.
NT
Also, if he has been investigating failed concrete structures, he has probably totally ignored the 'human factor'
Contractors are far more likely to pad out the mix with any old crap they can grind up and feed into a mixer, or simply not throw as much in. And swear blind it was all in date, not clumped and otherwise somebody else's problem.
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