home brew mix which sand ?????

[hoss]

hi, I've started my pizza oven over the last couple of weekends and i am nearly ready to build the dome, i have seen lots of measurements on here for home brew, but no mention of which sand to use not that i have seen should i use yellow builders,plastering sand, kiln dried please help as i would like to start tomorrow excellent site by the way i will post some pics very soon cheers in advance Dave

[faz]

I used normal builders/soft sand on my build, apart from where I knew I would have big gaps to fill with homebrew and then I added some sharp sand (about 50% I seem to remember) just to reduce the likelihood of it cracking as it dried.

Good luck with your build. You'll soon get used to how sticky homebrew is and use that property to your advantage - it grips bricks pretty tight fairly quickly which means you don't need to prop things up until you get to the upper courses.

[hoss]

cheers faz i have came across a post some where on the net that said use plastering sand but cant find the post again

[spinal]

If you're looking at wickes, go for the red bags of "building sand".

The yellow and the blue bags have far too many pebbles inside to get a smooth finish.

M.

[nixie]

Glad this post came up. So far I've used the Wickes sharp sand (yellow bag), however as spinal says its got a far number of bits in it. Thinking I might use the building sand for the dome (so far all my clay is in the floor).

[spinal]

I've gone through several bags of wickes sand... if buying from wickes, here's my tuppence

Yellow bag (sharp sand): don't bother. Lots of small bits that make it useless as mortar (unless you like thick/rough joints). The bits are too small to use it in concrete unless you add more pebbles.

Red bag (building sand): best in terms of price/quality. Perfect for mortar. This is the one I used most, just be careful as it has a high water content so don't add it to cement before you need to use it.

Blue bag (ballast): good for concrete if you're too lazy to buy pebbles yourself (green bag, pea shingles)

Orange bag (plasteric sand): like the building sand, but less "orange" in sand colour. Too expensive for no improvement over the building sand.

Grey bag (silver sand): again, no major improvement over building sand but higher cost

Block paving sand/kiln dried/other sands: haven't tried these.

On that note - if you're buying sand, don't bother with the 1-tonne jumbo bag. When you count shipping, it's cheaper to buy the 25kg bulk bags and carry them yourself. Just remember to buy 10+ bags a go to get the cheaper rates

M.

[cannyfradock]

Here's my thoughts .....

The "homebrew mix"...which probably originated from the FB forum states a mix of sand, hydrated lime, powdered fire clay and cement at a ratio of 4:1:1:1. I use the normal builders sand from my region.(S.Wales) It's dredged and washed sand and the same stuff you find on most beaches. If the sand is very fine grade, then I would push the ratio to 5 or even 6:1:1:1.

Terry

[bookemdanno]

If your mortar mix slumps or cracks in a half inch or more thick joint, then some sharp sand will be better used.
Most mortars are soft sand like Terry says.
I find the ready mixed stuff has too fine a sand in it.

Sharp sand has larger irregular grains that create a stronger mortar, but it has less life in it.
Washed soft sand has smaller more rounded grains.
Buillders sand is usually not washed so much, so retains a bit of clay in it.
Kiln dried is very fine, dry sand, best for very thin joints.

[stefan]

I've just started on my first course and ran into the issue of the mix cracking when it dries. Seems I have not used enough sand, and I certainly didn't add any sharp sand...

Looking at the photo do you think I need to start again, or is it ok to improve my mix going forward? Note that the storage heater bricks will be topped with a layer of clay tiles so most of the cracked joints will be below the cooking surface.

PS: this is my first ever building project.

Cheers

Stefan

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[spinal]

Stefan - looking at your pics, i would suggest too much fire-clay, and too little aggregate. Aggregate can be grog (crushed fire bricks) or sand, depending on preference.

What mix did you use?

[bookemdanno]

Stefan, that looks like your bricks are sucking the moisture out of your mortar too quickly.

You should be ok with soft builders sand at the ratios that Terry mentioned. Get an old ice cream tub or something to be a gauging box. This ensures that you get much more exact ratios.

Give your mix plenty of time in the mixer to get nice and fluffy, and like a cake mix. Take a bit from the mixer onto a trowel, tap it and invert it, it should stay there.
Get a course worth of your bricks soaking in a bucket of water whilst your mixing. Say let them have a drink for a couple of minutes, and then have a good five minutes to dry off (get the running water off the outside) before laying them.

You'll possibly need some sharp sand in the mix to point up the outer joints as you get higher up the dome. But stick with soft builders sand for the main laying of the bricks and the internal pointing.

[cannyfradock]

Stefan

I totally agree with Danno and spinal's comments/tips....and I also agree that your mix looks a little rich.....a little more sand needed.

This is your first ring course so the perps (or gaps) are not that big so I don't see any need to re-lay your first course. Take on all the advice and lay a few more ring courses.......still "shout out" if you're having problems.

Myself......I wouldn't lay clay tiles over your storage heater bricks.....some do....I don't. Any gaps between the SH bricks will soon fill with consolidated ash during the oven curing stage.....(I could be contradicted here)...

Great start....and please post your next stages.

Terry

[stefan]

Thanks to all who replied, it's evident that my mix was wrong. I incorrectly assumed that it would be better to have a bit too little sand but the opposite seems to be the case.
I had also mixed the homebrew by hand which may have contributed to the cracks.

I'll get a mixer, and will use 5 parts of sand for the next course and see how that goes. I think I was using 4 parts sand max initially, maybe closer to 3.

Best wishes,

Stefan

[pete123]

Don't mix too much at once as it soon goes off especially if it's warm. Covering it with a tarp is good to keep the sun off. You can also lightly spray a mist of water over it. I dunked my firebricks in water for a few seconds to stop them sucking the moisture out of the homebrew.

[pete123]

...mist the homebrew, not the tarp.... I didn't make it very clear.

I may be wrong though. Others may have other opinions.