# Forum Home Renovation Brickwork  Lime in Mortar Needed?

## lukelegend

I'm about to build my first besser block wall, about 4 blocks high and 7 meter long. I have picked up the builder loam from the landscaping place and the cement bags. I was going to mix it 4 sand and 1 cement but on the cement bag it says 6 sand, 1 cement and 1 lime. 
Do you really need Lime in the mortar mix? What is Lime used for? Can i get away without using Lime and is the mortar ratio 4:1 ok to use?

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## autogenous

12 sand, 3 GP Cement, 1 lime or 
12 buckets sand, 3 buckets cement, 1 bucket of lime to that proportion. 
You could go to 14 sand but that may throw it out of spec. 
Mix it slightly stiffer than brick mud. 
How course is the sand?

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## autogenous

Lime provides workability and also provides strength. 
The more cement you put in it to ratio the faster the mortar will go off. 
Lime is like part B of a masonry epoxy.  If you use straight cement no lime the mix will go off real fast. The mortar will segregate when trying to slide spread to the side of the block.
You are trying to achieve a 3 to 1 aggregate matrix ratio. 
Slightly more cement in a block mix helps it to go off a bit faster so the blocks don't sink or shift.  http://en.wikipedia.org/wiki/Lime_mortar

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## myla

hi, 
yes lime is crucial, it makes it "sticky" and therefore sticks to the trowel/block better 
some sands have high clay content which also provides a level of "stickyness" to the mix, typically the bright red/orange sands 
for bricks/blocks i go for 5 sand, 1 cement and 1 lime 
thanks

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## autogenous

Watch this guy slide spreading in this video 
Hes the s%^&. Even using the back of the trowel. His neck must be like the trunk of a 100 year old tree. 
And, and hes laying overhand. Hes the s$#% 
Its a Philadelphia pattern trowel which is suited to block laying. 
[ame="http://www.youtube.com/watch?v=8VGjA66RSm0&feature=related"]YouTube - Brick Laying and Masonry[/ame] 
[ame="http://www.youtube.com/watch?v=SJXrkAebzc0&NR=1"]YouTube - Laying the Block[/ame]

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## autogenous

If you look carefully he's over 30 feet from the ground. :Smilie:

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## Blocklayer

It depends on the sand.  
Some sand is 'fatty' and makes easy to use mortar that goes off slowly. You don't need lime here (just plenty cement) 
Some is 'sharp' and is hard to spread and goes off very fast. Lime can help here. 
What can happen is, if the sand is sharp and starts to go off before you get it all used, when you 'knock it up' (add water and re-mix again) it will weaken the mortar. Do it 2 times or more and the mortar is uselss. The sharp sand probably makes stronger mortar (with or without lime), but it's harder to use and if you need to knock it up, it ends up weaker. 
At any rate, lime is cheap, its your first go, and your wall is small. I'd use it. Keep it off your hands though, it burns like &^*&^ in a cut or worn fingers. 
Probably most important is to make sure you're ready to go before you mix the mortar. Notice in the video autogenous posted, the bloke is working comfortably, with mortar on raised boards not to far apart and the blocks are stacked right at hand and a comfortable distance from the wall. This makes a HUGE difference.  
There should be about 72 blocks in your wall (17 + 1/2 per course). The first course is the most important to get right and hardest to lay (do the whole course first). So I'd mix enough for the first course first, to see how you go. Is the footing nice and smooth and level? 
:

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## lukelegend

Thanks guys, that helps heaps. I'll be off to bunnies in the morning to pick up some lime.  
I've probably got too much cement ( 5 bags ) I guess i can use that on other projects. I only picked up 1/5th of a cube of builder loam (sand) for the job, Would that be enough for the 70+ Blocks or should i go and get some more? 
Yes the footing is 400 wide and 35 deep with trench mesh. I was told that would be ok for the job. it's level and smooth. 
That guy in the video looks like he has done it before  :Wink:

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## lukelegend

Ok, i've just popped down to bunnies and met some guy in the cement section who is a brick layer and he told me not to get Lime and just use a drop of dishwashing liquid per bucket of water and it will do the same thing. Is this true? Is there any adverse effect?

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## Blocklayer

Again, it depends on the sand/loam. You may not need lime, but a little shouldn't hurt.  
Be VERY careful with detergent. I would not use it.
Detergent will make the mortar easier to work and go off slower, but even a little bit (too much) will ruin the mortar. Its REAL easy to slurp too much in the mix. You can get proper mortar mix additive thats safer, and again, don't use too much 
0.2 m3 loam should be heaps for the job. 
I hope you meant 350 deep and not 35 ! 
Also, if this wall is a retaining wall and will be core filled, the strength of the mortar is not so critical. But if it's not, make sure its good mortar. If the loam is sharp, adding more cement will also make it more 'creamy' and easier to work. Just don't mix too much at a time. For your first go laying 70 odd blocks, it will probably take you all day, so if you mix a big batch, your mortar is likely to go off before you get it used up

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## lukelegend

Thanks for all the advice people  :Smilie:  
I've gone and brought some plasticiser rather than the lime or detergent ideas i had. 
It's supposed to be the best thing to use in the mix. 
I'll probably get started next week as i have some time off and see how i go  :Smilie:  
Thanks again

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