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Bagged premixed lime mortar for tuckpointing

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#121 ·
I see, well I have done some lime mixes with buff and red brick dust and it definitely affects the color. The red makes a pastel pink and the buff gives an ivory, just as you would expect. Which one is better for the mix, I do not know. The pink sample has been hanging on my fence for 5+ years though, and while hard can still be scratched with a fingernail, although it does not dust. The ivory sample I can't find, so it was probably trashed years ago.
 
#122 ·
mortar

I have away for a week, this discussion is real interesting. I started burning brick as a hobby a couple years ago. I use a scove klin or clamp as it was called in COLONIAL WILLIAMSBURG. Used coal,soft & hard,along with oak,hickory and ash for fuel. Tried several clay deposits,the color of clay does not effect final color.Have used blue/gray clay along with tan clays. If any of you guys are interested a free book can be read called 60 YRS.A BRICKMAKER by A guy called CRARY. HE was born in i believe 1814 & wrote the book in the 1890s very fon read. Or type in WILDCATBRICKCO he has a link to that book it is free & complete on computer. I have to admit my computer skills are the closest thing to non existent or i would show pictures.
 
#126 · (Edited)
To sum it all up

Gentlemen,

After reading the smeaton project findings and following your discussion - I will be parging a stone and mortar basement (circa 1914) soon. I planned to use either a type N or a homemade type O (no one seems to sell a premade one) by adding 1 part type S hyrdrated lime by volume to the off the shelf Type N cement mortar and of course sand. Since I am working on the inside on a natural stone (appears to be limestone) I am not concerned with excessive compressive strength, and since the existing mortar is in relatively good shape (i.e., not a repointing job), will not be exposed to the elements or any freeze-thaw action, my primary concern is vapour permeance and then durability.

Will a type N (1:1:6) or type 0 (1:2:9) (c:l:s) mortar have enough permeance to avoid the often discussed problem of trapping water in the wall?

The other side of the wall is (unseen) but likely not dampproofed.

Thanks in advance for any help.

I have talked to a couple masons on different sites and they look at me like I have two heads when I mention lime mortar; both have recommended type s with an admixture to increase adhesion. Is it possible that given the sheltered relatively good shape, that something more durable like a portland sand mortar would be good enough?

sorry for all the questions
 
#127 ·
Why use OPC at all? I parged my cellar with masons lime and sand close to 10 years ago. No problems with it. Since you have such a soft stone, you have no need for hardness. I have even used masons/lime sand on the exterior for pointing and have had no durability issues.
 
#128 ·
I only considered using OPC for the time saving aspect and the (perhaps false) assumption it will be more durable; i can't find lime putty anywhere - only hydrated lime. Can I mix the hydrated lime with sand and water on the spot or do I need to make a putty first?
 
#131 · (Edited)
Has there been any resolution to the best historic lime pointing mortars? Is it still deemed safe/ best to use a 1:1:6 Portland:lime:sand mortar for an old outdoor (cold-climate) limestone foundation for example? What is the observed lifespan of such pointing jobs in a freeze-thaw climate if done properly?

I've played around with some ordinary hydrated type S bagged lime with sand mortar (no OPC) and it really spread with trowel nicely, but it looked and felt like soft toothpaste even hours after I applied it.

Of course mixing up the terms "hydraulic" and "hydrated" seems to be a common problem for everyone but those in the lime business.

Since hydraulic lime is made by super-heating in a kiln to combine the ingredients CaO and SiO2 into calcium silicates at the high temperatures then I think it would be more comparable to Portland, and would be a very different product than could be had by taking ordinary hydrated type S lime and mixing it with a pollozan (without being cooked together at the high temperatures).

It seems to me that it's not so important as to whether a hydraulic lime is natural (naturally occuring NHL) as it is important that the ingredients CaO and SiO2 are proportioned and mixed together before they are kiln cooked together to chemically combine as opposed to mixing the CaO and silicas at normal room temperature where they are not chemically combined.

I've studied that bagged hydrated type S lime based mortar is suitable only for indoor use or protected outdoor use with very low compressive strength. Hydrated type S lime based mortar with added pollozans is a bit faster setting and harder, but still questionable for outdoor use. NHL (various ratings) hydraulic based mortars are fully safe for exposed environments but are much more expensive $. And, 1:1:6 OPC:hydrated-lime:sand mortar is a common compromise here in the USA for older pointing of stones and brick.

I've seen that virginialimeworks.com has a product Building Lime 200 that is described as composed of hydrated lime and pollozans to create a hydraulic lime just like "the ancient Romans" used. I'm skeptical if it is just hydrated type S mixed cold with a pollozan (ingredients not kiln cooked together). That could be a great money-making scheme because of how low cost type S lime is available. You could make it yourself cheap. Would this mortar really be quality compared to kiln cooked hydraulic lime that costs much much more $$ money?

That seems to be what I've studied so far. Does this seem to be accurate?
 
#132 ·
I don't think it is accurate. You are saying that an NHL would be more like OPC than Regular lime mixed with Pozzolans but the research has shown that NHLs and Lime mixed with Pozzolans or brick dust react more similarly.

If you are using 1:1:6 as an historic re-point mix you are using a type N mix which would never fly in any true restoration I have been a part of, below grade would be a possible exception.

I do agree that it most likely makes little difference whether the NHL is natural or is formed by burning the silicate and the calcium carbonate together.

No comment on Virginia Limeworks since I have no experience with them

Oh and as for the BEST mix...each situation is different and requires it's own mix
 
#133 · (Edited)
Dom

What is the current ratio of OPC:lime that you can not go less than (on the OPC) because the mortar starts getting weaker and less compressive strength?

Does this rule out Type O and Type K mortars? Or, are they reasonably strong and lasting and do not separate? I know that the studies have shown that a 10% addition of OPC to hydrated lime mortar only makes it weaker than the ordinary lime mortar. But, what is the percentage of OPC addition where the lime mortar gets stronger from the OPC addition (because the OPC strength takes over)?

Also, who sells good China Clay around here? HJ Mohr in Oak Park, IL has bags of private label China Clay for $21.00 per bag with no markings or description of contents.

US Heritage Group in Chicago advertises NHL 3.5 hydraulic lime for about $44.00 per bag. Other than these I don't see much advertised in the lime mortar department here near Chicago, IL.

Of the three choices...
1) Hydrated (cheap!) lime and china clay w. sand
2) NHL 3.5 and sand
3) hand mixed Type O hydrated lime and OPC w. sand

..what would you feel most durable and best method for an older limestone foundation of a house?

Thanks,
Tim
 
#134 ·
timp said:
Dom

What is the current ratio of OPC:lime that you can not go less than (on the OPC) because the mortar starts getting weaker and less compressive strength?

Does this rule out Type O and Type K mortars? Or, are they reasonably strong and lasting and do not separate? I know that the studies have shown that a 10% addition of OPC to hydrated lime mortar only makes it weaker than the ordinary lime mortar. But, what is the percentage of OPC addition where the lime mortar gets stronger from the OPC addition (because the OPC strength takes over)?

Also, who sells good China Clay around here? HJ Mohr in Oak Park, IL has bags of private label China Clay for $21.00 per bag with no markings or description of contents.

US Heritage Group in Chicago advertises NHL 3.5 hydraulic lime for about $44.00 per bag. Other than these I don't see much advertised in the lime mortar department here near Chicago, IL.

Of the three choices...
1) Hydrated (cheap!) lime and china clay w. sand
2) NHL 3.5 and sand
3) hand mixed Type O hydrated lime and OPC w. sand

..what would you feel most durable and best method for an older limestone foundation of a house?

Thanks,
Tim
Click to expand...
Well I don't really think that there has been a consensus. The smeaton project basically says don't use less than a 1:1 ratio of lime to Portland, but they do suggest using NHLs, pozollans and brick dust.

When you ask about type O an K it is an impossible question because you aren't saying how you are creating that mix. I know I've seen type O mixes made with OPC rather than pozzolans that have lasted 20 years (not work I've done) however research has shown in other circumstances that it doesn't last and that the Portland and lime separate.

I don't have an answer to any of these questions really, except that use of an NHL or using Pozzolans hasn't resulted in any problems. My problem is that neither of those are available to me at all.

Oh and in my opinion, i think a 1:1: 6 or maybe a 1:1:5 would be a suitable below grade mix.
 
#136 · (Edited)
dom-mas said:
Well I don't really think that there has been a consensus. The smeaton project basically says don't use less than a 1:1 ratio of lime to Portland, but they do suggest using NHLs, pozollans and brick dust.





There has been so much discussion about the ratios however,i believe it was in the book Building With Lime by Michael Wingate that the ratio was stated. I know in his book he said the opc should NOT be less than 50% of the lime
Click to expand...
 
#137 ·
fjn said:
dom-mas said:
There has been so much discussion about the ratios however,i believe it was in the book Building With Lime by Michael Wingate that the ratio was stated. I know in his book he said the opc should NOT be less than 50% of the lime
Click to expand...
Right but there have been other books that advise using OPC as an additive of 1/4-2/5 of the cementicious materials. Seeing how the back to lime movement is only what? 30 years old or so which is negligble to the life of a masonry structure (hopefully) all the research is mildly suspect. Remember how doctors were saying that eggs were evil 25 years ago, now they're saying their one of the healthiest proteins to eat.

I guess what I'm saying is that unless you're making a mix exactly how it was made for that building 100, 200, 300 years ago, only our children and grandchildren will know whether we made the right choices.

Therefore, in my opinion, the use of straight lime, natural NHLs of the proper comp strength and occasionally lime with fly ash or other pozzolans are about foolproof. I on the other hand do continue to use OPC as an additive because really I have no other choice, and i would rather put in a soft mix that doesn't last rather than a type N in most situations.
Click to expand...
 
#138 ·
dom-mas said:
fjn said:
Right but there have been other books that advise using OPC as an additive of 1/4-2/5 of the cementicious materials. Seeing how the back to lime movement is only what? 30 years old or so which is negligble to the life of a masonry structure (hopefully) all the research is mildly suspect. Remember how doctors were saying that eggs were evil 25 years ago, now they're saying their one of the healthiest proteins to eat.

I guess what I'm saying is that unless you're making a mix exactly how it was made for that building 100, 200, 300 years ago, only our children and grandchildren will know whether we made the right choices.

Therefore, in my opinion, the use of straight lime, natural NHLs of the proper comp strength and occasionally lime with fly ash or other pozzolans are about foolproof. I on the other hand do continue to use OPC as an additive because really I have no other choice, and i would rather put in a soft mix that doesn't last rather than a type N in most situations.
Click to expand...
That is a good rule of thumb,it is like the first rule of medicine,DO NO HARM.:thumbsup:
Click to expand...
 
#140 · (Edited)
dom-mas said:
There has been so much discussion about the ratios however,i believe it was in the book Building With Lime by Michael Wingate that the ratio was stated. I know in his book he said the opc should NOT be less than 50% of the lime
Click to expand...

Mortar mixtures of Portland-Lime compositions of Types M, S, N and O are all composed of ratios having Portland being at least 50% or more of the lime content. Only type K would have a Portland content of less than 50% assuming by volume to the lime. Type O would have the 50% Portland to Lime composition of 1:2:9 Portland:Lime:Sand. This is assuming you mixed it yourself with actual Portland and Hydrated Lime as opposed to buying a mason premix which would actually likely contain Ground Limestone instead of Lime. Even Brixment is made with ground Portland and ground Limestone which is not reactive like Hydrated Lime.

So, M, S, N, O mortars look like they are within that theorized limit of requiring a Portland content of equal or greater than 50% of hydrated Lime content limit to be of sound quality. *edited

But, as mentioned if you really are preserving a softer stone building then you may as well go with the NHL Hydraulic lime, or the Hydrated Lime+calcined metakaolin mixtures because the M, S, N, O mortars are relying on Portland as their primary binder and Hydrated Lime as a plastic workability sticky agent -- which makes them unyielding and less porous.

And, it is important to note that most premixed mason cements and mortars do not even utilize hydrated lime. If you can find the spec sheets for alot of premixed products they are using ground limestone as the "lime" in the mix. I don't actually know which qualities of ground limestone are similar to actual hydrated lime other than making the mortar more plastic.

An interesting note is that some of the Portland-Lime studies I've seen tested the hydrated Lime mortars using a putty and having a Portland content listed as 10% of the WEIGHT of the Lime cement...and resulted in that strength decrease compared to an ordinary Lime putty mortar. A 10% WEIGHt of metakaolin increased the lime mortar strength. But, when we start comparing weights vs volumes it get's confusing. A 10% of weight of a lime putty can be a lot of volume.*

source of this study:
The Use of traditional Limes For Lime Mortars by Violeta Bokan Bosiljkov, Slovania 2001
 
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