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CEMENT - GOING OFF?


bixy

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Don't laugh, but does anybody know if cement goes off after a couple of years? I'm using multi-bat and recent rendering work I've done can just be scraped away with a fingernail. It just isn't going hard. Am I perhaps getting the cement -sand proportions wrong? I'm using about 3 to 1. Is that right? Help please before my house falls down!

Patrick

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Your proportions should be 3 sand to 1 cement.  Cement normally keeps for a year (bags are usually date stamped).  You may get away with longer in a very dry place but not recommended.

Is this stonework you are rendering, or brick?  For stonework chaux is recommended rather than cement as it lets the stone breathe and avoids sealing in damp.

PS - If you measure by the level bucketful you get a more consistent mix than by the spadeful.  3 ten-litre buckets of sand to a 10-litre bucket of chaux.

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hi

         ok yes is does go off, has it got lumps in it ?? if yes dump it !

    your mix for the first or scratch coat is a bit strong try 3.5 - 1 with multi-bat and a 4-1 for the top coat .

        make sure your sand is clean washed sand as this causes the sort of problems you are having ,but  muti-bat does have lime in it and can take a few days to set hard.

         hope tis helps

             dave

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Another thought.  If you're doing a roughcast render finish, or you're brushing off to reveal some stonework, and you're not brilliant at flicking the stuff on with a trowel (I'm not), try whacking the render on using rubber mason's gloves, squishing it into the gaps and rubbing it in all over the surface.  Produces the same effect as 'bag rubbing'.  I can do twice as much in the same time with gloves compared to a trowel and end up with hardly any on the ground.  A full barrow load in an hour.  It's not the pro's way but it works just as well.

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hi

     ok you will have to find the way that`s best for you , I too have tried the "French way " a wet mix and throwing it on was going to swear at this point but thought better of it .Having done a few  stone Welsh cottages  went back to my old trusty gauging trowel ,mortar board and spot board for the first coat , but like they say wet the wall with a garden sprayer first and when you think it is wet enough wet it again , you will find a lot of difference with a 3.5 - 1 mix because of the lime it is more " creamy " use buckets to measure the mix as said , oh and try and get the 0-2 sand not the 0-4 or 0-8 ,it`s still gritty but easier to use.

good look and just ask if you have more problems someone here will only be to glad to help

                 dave

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Thanks for all the answers. So I'm right to use Multi-bat then? It has lime in it and is therefore the right stuff for old stone walls? I'm kind of confused because I hear a lot about chaux, which I believe is sand and lime. About the Multibat going off, it has not gone hard or has lumps in it, so is it still usable? As for wetting the walls, what I do is first apply dilute builders adhesive, let it dry, then just before rendering apply the same again and then render. Seems to stick okay. The problem comes later - the mortat seems very friable. Perhaps the mixture is very wrong. Another novice question. Does putting in more Multibat [or cement] into a mixture make the result stronger?

Thanks once again.

Patrick

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[quote user="bixy"]So I'm right to use Multi-bat then? It has lime in it and is therefore the right stuff for old stone walls? I'm kind of confused because I hear a lot about chaux, which I believe is sand and lime.

[/quote]

I've never used Multi-Bat so I DK on that.  Chaux is lime.  I use chaux and sand only for rendering.  I wet the walls with water only.  I know some prefer a dryish mix but I find a sloppy (stiffish cow pat) mix easier to apply as it gets into all the cracks more easily and I still have no adhesion problems.

The bags of chaux I have say use within 12 months of the date stamped on them as long as they are stored in a dry place and not opened.  The ones I have are plastic lined so maybe the 2-month limit bags aren't lined.

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