How long does your mortar last before going off?

[pilsbury]

I'm mixing 4:1 sand and cement with plasticiser. My mortar lasts about 2 hours max before going unworkable. After about 40 minutes it's already stiffening up from the buttery consistency I mixed it to.

Being the world's slowest block layer, this is an issue for me - what can I do? Retarder? I can't mix less than 6 shovels of sand a 1.5 of cement in the mixer which almost always leaves some waste in every mix.

 

[oldbutnotdead]

Work faster . Same as you (not the fastest)- speed comes from practise, get the right amount of mortar in the bed, use a line, don't get panicky about a mill or 2 out on a course. Your mixer sounds similar to mine- dump the mix into a couple of tubs, cover the one you aren't using. Splash a bit of water in if its getting that stiff that quick. Use plasticiser in the water (unless you've got lime in the mix).

 

[noseall]

We leave ours in the drum (shovel it out of the drum) when the pace slows down, so that you can spin it and add more water.

 

[Ian H]

I put 2 buckets (24l) of sand and 5l of cement in mine, it always needs another spin after a while even at nearer 5:1.

I'm slow as well, and rough

 

[23vc]

2 hours sounds about right, but by then hopefully you've used a fair bit of it?
I put it in 3 tubs straight out of the mixer and clean the mixer. Normally by the 3rd tub I need to add a splash of water, and give it a stir with the trowel. Takes about 10secs and I don't think it's a problem.
The thing that worries me about leaving in the mixer as per noseall, is I hate cleaning the mixer as I'm not very good at it, and I fear it would be harder to do with mix left in it for ages.

 

[pilsbury]

I think I'll dump my mix into tubs and cover.

Like the idea of leaving it in the mixer so it can have another wind half way through, but even now there's only just enough muck in there to start with to mix properly! Otherwise I just have a coating on the sides!

 

[23vc]

Btw my blockwork regularly takes me up to 3hours and my mix doesn't become "unworkable" - just needs livening up a bit when it's hot. Are you mixing it really creamy for long enough with a decent splash of plasticiser?
My brickwork is a lot quicker luckily

 

[Ian H]

Got any pics of your mix?

I wouldn't say mine was that creamy no matter how much Feb I put in, I knock the blocks down to the string line with a lump hammer too!!

When I'm done I chuck a bucket of water and a few bits of slate in the mixer, seems to clean it pretty well.

 

[^woody^]

If you wait until a cool damp day between October and December you will get an hour or two extra to use it.

Or order some Readymix.

 

[23vc]

Got any pics of your mix?

I wouldn't say mine was that creamy no matter how much Feb I put in, I knock the blocks down to the string line with a lump hammer too!!

When I'm done I chuck a bucket of water and a few bits of slate in the mixer, seems to clean it pretty well.

If you're laying dense blocks (ie not thermalites) then I'd say my mix is just firm enough to stop the weight of the block squidging too much mix out and the block sitting too low. It never needs any encouragement from the hammer. Need to mix it long enough say 10mins, consistency needs to be so you can run your trowel through it with virtually no resistance.
Or like woody says it's that consistency which you see from the big tubs delivered to sites if you ever get to see brickies at work or maybe YouTube it

 

[pilsbury]

Need to mix it long enough say 10mins, consistency needs to be so you can run your trowel through it with virtually no resistance.

Hmmm.... might not be mixing long enough and mixing a bit too stiff.

Only trouble is when I'm doing small mixes the muck just sticks to the outside of the mixer and goes round!

 

[Ian H]

Mine sticks too, I can just about scrape it with the shovel before the next mixer paddle comes round. Leave the shovel in too long and you get a whack in the nuts

I haven't done anything that will be visible yet so all info is great, cheers

I think I just found a good match for the bricks on my house too, Ibstock Aston Red Sandfaced 73mm. Just need to find them in stock somewhere so I can pinch a sample.

 

[23vc]

Only thing I can advise as being in the same position myself, is try to go faster so you can at least put down 10sand 2 cement or whatever is enough to mix properly in the drum. Look at how your doing it, do all your blockwork cuts beforehand, etc. It's as much the mental side of it ie. Planning which speeds you up. it takes me a good 3 hours to get that amount down in blocks (25 to 30 blocks worth) , for bricks I'm doing better at about 70 in under 2 hours, but I've been doing it since Easter and am now at second storey eaves height.

 

[pilsbury]

I may have a world record with 15 blocks in 2 hours! So a rate of 7.5 blocks an hour! What does a decent brickie do block wise per hour?

With some of these tips, today has been better. I have mixed my muck looser, let it mix for about 8 minutes and had my hand in the mixer with a trowel scraping the sides as it goes round to let the muck fall of the sides and mix. I have also spent more prep time getting everything in place and will get cuts done before I mix the muck in future.

You never know, I may soon be boasting 10 blocks an hour.....

 

[Ian H]

I think I just found a good match for the bricks on my house too, Ibstock Aston Red Sandfaced 73mm. Just need to find them in stock somewhere so I can pinch a sample.

Very pleased with the match!!!