# Making lime mortar



## gregzoll (Dec 25, 2006)

Go to the local Concrete yard with a sample of the mortar. They can make up a mix for you or give you a recipe and pull the materials from the yard in the quantity that you need.


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## Tscarborough (Mar 31, 2006)

Redguy, put the Type S lime in a bucket and keep it covered with water. The longer the better, but at least 24 hours. Mix with 2-3 parts sand (to what feels workable) and carry on. As long as the lime is covered with water, it will last and be ready to use.


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## redguy (Jun 1, 2014)

Would it hurt to mix in Portland cement at 10% to the mixture?


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## tony.g (Apr 15, 2012)

redguy said:


> Would it hurt to mix in Portland cement at 10% to the mixture?


Have a read of this regarding the advantages and disadvantages of adding OPC to a lime mix.

http://www.buildingconservation.com/articles/cement/cement.htm


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## Tscarborough (Mar 31, 2006)

Better to add brick dust than portland, but also at low (>10%) amounts.


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## Robpo (Mar 30, 2014)

You really don't have to slake the lime. Just mix the two together and then add water. Two to one seems a little lime rich but it will work. I usually use a ratio of one part lime, two parts cement, three parts sand. Up to one lime to one cement will work. 
I don't know the ratio of sand to cement in the sand mix is so I can't tell you how much lime to use.
The easiest way to go would be to use a mortar mix and just add water.


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## redguy (Jun 1, 2014)

tony.g very good article, thanks for the link.

Lime and sand it is.

Thanks all for the replies.


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## TRUEPRO (Apr 10, 2012)

Not sure why people overthink this. A type s mortar with a small amount of portland is used for natural stone. Keep it simple folks there is absolutely NO need to discuss anything else. Thats like telling people the mixture of rubber to help them change a tire. REDICULOUS!!!


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## ccbs1 (Jun 2, 2014)

I have always used Type-N for stone foundations. Not as hard as Type-S and has a longer set which makes it easier for a non-pro like me to use it. Tuck point it then 12-24 hours later depending on temperature shape/clean it with a welding slag hand brush and smooth it out with an acid brush. Nice looking joints this way even if you suck at tuck pointing.

If you decide to use lime mortar, fly ash will act as a pozzolan just like brick dust does.


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## jomama45 (Nov 13, 2008)

TRUEPRO said:


> Not sure why people overthink this. A type s mortar with a small amount of portland is used for natural stone. Keep it simple folks there is absolutely NO need to discuss anything else. Thats like telling people the mixture of rubber to help them change a tire. REDICULOUS!!!


I don't think you comprehend the issue here. There was no Type S mortar, or Portland cement, available when this rubble foundation was built, thus it contains lime mortar. Patching with anything but lime mortar will only create a myriad of additional problems down the road, which you obviously already should know if you truly have any masonry background.............


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## Tscarborough (Mar 31, 2006)

Not only that, Truepro, but normally, stone will require a Type N even in modern construction. Exceptions would be something hard like granite in a structural (as opposed to veneer) situation. Best practice is to always use the weakest mortar that meets design criteria, and it should always be softer than the units being laid.


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## Robpo (Mar 30, 2014)

I'm not sure but I think type N lime needs to be slaked and type S has all ready been slaked. Not real sure of redguy's situation as far as how old the foundation is and what type of mortar was used. I wouldn't think cement would add much strength even if 1 to 4 ratio of cement and lime were used. It would make for better adhesion.


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## Tscarborough (Mar 31, 2006)

The difference between N and S moisture content (75% VS 85%). Neither need to be slaked in the true sense of the word, but both will produce a better finished product by being covered by water for periods of time, the longer the better, before use.


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## redguy (Jun 1, 2014)

Robpo, part of the house was built pre 1900's, the part I will be doing most of the work to was built around 1910.


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## jomama45 (Nov 13, 2008)

Robpo said:


> I'm not sure but I think type N lime needs to be slaked and type S has all ready been slaked.
> 
> There's no truth to any of this........
> 
> ...


According to who????? Do you really think "cement" is used for "adhesion" in mortar???


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## stonecutter (May 23, 2014)

TRUEPRO said:


> Not sure why people overthink this. A type s mortar with a small amount of portland is used for natural stone. Keep it simple folks there is absolutely NO need to discuss anything else. Thats like telling people the mixture of rubber to help them change a tire. REDICULOUS!!!


And for strike three, adding Portland to Type S mortar pushes it closer to Type M...too strong for any stonework.


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