# Forum Home Renovation Retaining Walls  Mortar Mix for Rock Wall

## Flyboy

G'day,
Just wondering what the best mix of mortar for a stacked rock wall would be. I was told to use "about 3:1 sand/cement with a bit of lime" which is a little vague. I googled it and came up with all sorts of numbers from 2:1 up to 6:1. 
Also, I had heard that the lime is added to make the mortar more workable but there are better products around than lime. If so, what should the lime be replaced with? 
Thanks

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## ozwinner

> G'day,
> Just wondering what the best mix of mortar for a stacked rock wall would be. I was told to use "about 3:1 sand/cement with a bit of lime" which is a little vague. I googled it and came up with all sorts of numbers from 2:1 up to 6:1. 
> Also, I had heard that the lime is added to make the mortar more workable but there are better products around than lime. If so, what should the lime be replaced with? 
> Thanks

  Mix should be 6.1.and.whatever lime makes the sand workable. 
Apart from making the sand workable, Lime has a self healing process if the joint every cracks, Im talking hairline cracks, not gaping cracks from foundation failure. 
Al  :Smilie:

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## Flyboy

Thanks Al.
Roughly how much lime would you use, or how do you tell when the mortar is workable? Read somewhere that the mix is 6:1:1 sand/cement/lime. Is this about right? 
Cheers

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## journeyman Mick

I was told, both by my blocklayer neighbour and by a landscaper mate who does stone retaining walls that you shouldn't use brickies loam in mortar for rock walls. Preffered sand is sharp plasterer's sand. Something to do with too much shrinkage due to the clay in brickies loam coupled with stone not being as porous as bricks and blocks.  
Mick

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## ozwinner

> Thanks Al.
> Roughly how much lime would you use, or how do you tell when the mortar is workable? Read somewhere that the mix is 6:1:1 sand/cement/lime. Is this about right? 
> Cheers

  Lime all depends on the ammount of clay present in the sand, too much clay and you reduce the ammount of lime, sharp sand requires more lime.
You will know if its too much lime as you cant get the mud off the trowel, and visaversa with too little lime, as the mud just slips off the trowel.   

> I was told, both by my blocklayer neighbour and by a landscaper mate who does stone retaining walls that you shouldn't use brickies loam in mortar for rock walls. Preffered sand is sharp plasterer's sand. Something to do with too much shrinkage due to the clay in brickies loam coupled with stone not being as porous as bricks and blocks.  
> Mick

  True, the clay in sand does tend to shrink an awfull lot, especially in hot weather, this is more appernt in large joints like you would use in rock walls. 
Al  :Smilie:

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