What is the cement/sand ratio for brickwork. I will be building a BBQ in the near future. Is it necessary to add lime to the mortar mix? If lime is required, can I use a plasticiser instead? If I can use, where can I buy plasticiser? TIA
Use a ratio of three parts sand to one part lime. The best lime to use is lime putty, sold wet in plastic tubs, but dry bagged hydrated lime from any builders merchant will do for most purposes. Buy it from a merchant with a rapid turnover and if you are not using it straight away empty it into a plastic dustbin of water. It will then keep for ever but the dry powder carbonates with contact to the atmosphere and gradually becomes less useful.
Don't use ordinary Portland cement - it is ugly, too hard, brittle, strong, liable to crack, sticks to bricks too firmly so they can't be recycled, and uses more energy to produce and gives off carbon dioxide during manufacture. Bad for the planet, bad for the people. Use lime instead and remember that most of the world's best buildings were built before cement was invented.
The ratio depends on the properties required for the application, so there isn't just one mortar mix. 1:3 or 1:4 would be fine for this application. You don't want the thing to fall over of someone leans against it, so for this application I would go nearer the 1:3 and/or add a small amount of PVA to the mortar mix to improve its tensile strength (about one teaspoon per two shovel loads of sand is what I use).
No. It's important when working on a lime mortar house, but is a bad idea for BBQ. It will create a weaker bond, which isn't what you want for this application.
Plasticiser will make the mortar nicer to handle, but certainly isn't essential. Unless you've done a lot of work with mortar, I doubt you'll notice the difference though.
B&Q, Wickes, builders merchant, ...
What are you doing about foundations? If you don't feel like digging a trench and pouring a proper foundation for a brick wall, something I have seen done is to lay lintels instead of the bottom row of bricks, which you could dig a small trench for if you don't want to see it. Concrete lintels are dirt cheap from a builders merchant.
For that job, anything from 1:3 to 1:6 by volume.
no
if you want
Tesco, Sainsburys, etc. The rock bottom price washing up liquid at 15p a litre does the job.
If you use lime to plasticise instead, use the same volume of lime as cement, as other proportions tend to fail prematurely. 1:1:6 is popular.
NT
Anything from 2:1 sand:cement to 5:1 or even 7:1 will hold bricks together.
Opinions are divided between the '2:1 will be imprevious, and therefore won't suffer water penetration and frost cracking' (but the bricks may) to 'i'll use something with lime that is so soft that it won't crack even if water does get in'
I ended up with a sort of 6:2:1 mix of sand:white portland:hydrated lime for a visually pleasant mortar. One time I ran out of cement almost and it ended up 8:1:2 and it set all right ;-)
Good tip
I have used concrete blocks on their sides in a 6" deep trench bedded onto a fairly strong mix.
Never thought of lintels..
Salt in washing up liquid can weaken the cement as it interferes with the curing process.
Mixes stronger than 3:1 shrink during cure and microcrack extensively. This makes them porous and prone to frost damage. The numerous microcracks undo the advantage of the stiffer mix.
I ended up with a sort of 6:2:1 mix of sand:white portland:hydrated lime
The old 9:2:1 mix fails routinely, as do many other cement/lime mixes. AFAIK 1:1:6 is the only cement:lime proportion that has been found to be ok. Cement and lime are uneasy bedfellows.
For the sake of completeness I suppose one could mention clay mortar, or even the old lime mud and straw recipes.
NT
Agreed - you usually need equal lime and cement
As is ignored so often, this really depends on the sand. 1:1:6 is quite strong and if the sand particle is large you could still get cracking.
Err, reality check here. The chap wants to build a BBQ. Strength is not important. Portland cement with careful attention to ratios is what you use when building multi-storey carparks, motorway bridges and runways for Jumbo jets. Not for BBQs. Lime is kinder to the planet than cement. Come to think of it, we'd be better off without multi-storey carparks, motorway bridges and runways for Jumbo jets so lets just drop this whole cement addiction thing. In fact, for a BBQ, I wouldn't even bother about the lime. Bond the bricks with a sand / clay mix roughly 3 to 1. For the clay you could dig it up from your garden. Remove the topsoil and use whatever is a foot down. (You'll be half way to a water feature at the same time) Most non-timber houses in the world are earth bonded with no cement. Earthquakes can be a nuisance but shouldn't trouble an English BBQ overmuch. Relax and enjoy the summer without stressing on mortar.
Foundation is already poured. Made a concrete mix, cement/sand/gravel 1:2:3 ratio, six inches thick, with some hardcore at the bottom.
Yes it is, more so than a brick wall in a house. You don't want the thing to fall over when someone leans up against it. Unlike a house, the brickwork doesn't have several tonnes of bricks on top of it to help keep it in place when your 15 stone relative decides to prop himself up against it.
I just buy readymixed sand/cement mortar (usually by Hanson) and mix it up with water. No idea of the ratio of the mix.
Christian.
Of his BBQs are anything like our old neighbours than raw sand would be best so the whole lot collapses at the first go :-)
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