High lime mortar is what I would call it.

 

I seem to be obsessed.

Anywy all the work cited earlier seem to in their turn cite "the smeaton project" or "Teutonico et al "which seems to also be the "smeaton project" From english heritage.

It's up on the net if you wish to browse. the basic conclusion that I found was that the use of brick dust as an additive (as much as the same content as the lime. WOW)was favourable. It increased compressive strength while keeping permeability. The use of Portland, LOWER than 1:2:9 was HARMFUL since it DID NOT raise compressive strength, flex strength or permeability. The only advantage that it had was in initial set and strength. The use of Portland higher than 1:2:9 was not deemed detrimental except for the fact that it may be stronger than the masonry units. I'm going to have to read it again as well as a Dutch study that was refferenced by a few others on the net, however....

These studies were done in the early 90's, 20 years ago. The conservation groups (Parks Canada and the Heritage Masonry division of Canada's Federal Public Works are the 2 that I've been involved with) that I'm aware of would certainly have access to this research and are still NOT requiring brick dust as an additive on any of the jobs that I've been involved with or have even heard of, including 3 Class I jobs that I've been on. it makes me wonder

 

Remember also that the European and English materials and terms are different than American ones. Type S lime is NOT a hydraulic lime. Hydraulic limes are basically limes that have impurities that provide the same function as adding a gauging material does for a non-hydraulic lime.

 

Mortar

Does anyone know where in U.S. one can buy pozzalons such as brick dust or a product i believe is called METOKALIN? If so what percent is used to lime? What experience did you have,favorable or not? Thanks.

 

After doing quite a bit of internet reading last night and this morning I'll post this site which I feel sets out best what the general consensus is in the British Isles at least as well as other western European countries.

http://www.doeni.gov.uk/niea/tn37_repointing_stone_and_brick-2.pdf

Very good layman terms. Straight and to the point.

 

Mortar

DOM MAS Great find! The one paragraph on cements conveys the point that i was trying to get accross.STUART45 posted the pages from the book by Wingate which substantiated that point. The posting by you succinctly supports those perspectives. Here it is verbatim from the text Cement------used to "gauge" a lime based mortar particularly in exposed positions,but current practice is to follow traditional mixes and to avoid its use completely. Wingate eloborates as to why one should not "gauge" a mortar with any amount of OPC . It seems as clear as a bell the practice is detrimental. If you think about the 1:2.1/8:9 mix expounded on in the Canadian paper you posted last night that mix those not violate my original posting stating that the volume of OPC needs to be 50% of the lime content. Again,GREAT FIND! Thank you for all your effort.

 

OK, I am changing my recommendations in the future.

Here is the source for the study:

http://www.scribd.com/doc/29910110/Smeaton-Project

And here is one that along with discussing the gauging issue also discusses another problem with lime mortars, the aggregates used.

http://www.tececo.com/files/conference papers/CarbonationOfMortarsandRequirementsSand040595.pdf

 

mortar

The info.from the Smeaton project certainly contains alot to digest.Thanks for all the research. The question i have concerns the dates of the two. It appears the info. posted by DOM MAS was the most current 2006. The dates from the Smeaton study seem to be from the late 80s and early 90s. I could have missed something though,with all that data.

 

The info.from the Smeaton project certainly contains alot to digest.Thanks for all the research. The question i have concerns the dates of the two. It appears the info. posted by DOM MAS was the most current 2006. The dates from the Smeaton study seem to be from the late 80s and early 90s. I could have missed something though,with all that data.

The date of the smeaton project, '92 was why I'm taking it with a grain of salt, since it was one study in one location although it used many different mixes. That was why I made the comment that since the groups that I've worked with/for have continued to use lime mortars with a portland content even though they must be aware of the smeaton project and others.

 

My understanding is that the Smeaton Project is long term and ongoing. I searched for the original material.

 

fjn:
BASF has a product Metamax (http://www2.basf.us/functional_polymers/kaolin/products/metamax/) that is a metakaolin. I would suggest contacting them to find a distributor in your area.

I have used old brick dust, which is really the same thing. Dust from new bricks I would expect to be a little different.

I would say try 10% of the mix or less. That should be plenty hard for most applications. You should compare various mixes with NHLs.

 

fjn:
BASF has a product Metamax (http://www2.basf.us/functional_polymers/kaolin/products/metamax/) that is a metakaolin. I would suggest contacting them to find a distributor in your area.

I have used old brick dust, which is really the same thing. Dust from new bricks I would expect to be a little different.

I would say try 10% of the mix or less. That should be plenty hard for most applications. You should compare various mixes with NHLs.

How much did the brick dust colour your mix?

It seems that the temperature that additives are fired at made a huge difference in their properties. I'm not certain but I'm fairly confident that new brick are fired at a much higher temp making their dust quite different from an older brick dust.

 

Well, Dom-mas, I still see specifications for metallic grouts which have not been the non-shrink grout of choice for at least 50 years, so I am not really stuck on tradition, especially when that "tradition" is also not even old enough to prove the life cycle of the material.

 

Oh I agree. Doing resto I often see specs that just say to re-point with type N. However the groups that I mentioned, particularly the masonry division of the feds is very interested in doing things properly, doing so keeps the division going when it should have been closed 10 years ago like the electrical and plumbing division and recently the carpentry division. They do a lot of research and tinkering. They were partners in the NRC study that I posted. They kept lots of lime putty in the shop as well as brick dust yet in the 8 months that I was there they never used either. I wonder if further studies, perhaps in a Canadian climate which is very different from British, made the findings of the Smeaton project not as relevant.

I still know a few of the guys down there, maybe I'll go and talk to them about it one day. This isn't to say that I won't start looking for hydraulic limes locally as well as pozzolans and brick dust. when I first started on my own I was very gung ho on resto so I asked around and no one stocked any of them, so I naturally went with the mixes I was familiar with. Maybe things have changed and I'll be able to find them.

One word about hydraulic limes. One of the studies I read said that hydraulic limes had little to no bond with fat limes. So there are drawbacks to NHL as well.

 

My take was not to use hydraulic limes any more than to use portland as a gauging agent. This is the exact takeaway from the discussion so far as I see it:

For Heritage tuckpointing, the best possible mortar is a high calcium mortar with minimal silacious or pozzolan gauging materials, and a coarser graded aggregate with minimal fines.

I do not think that is the best mortar for new construction, or even for repairs of recent (less than 100 year old) construction.

 

From my reading yesterday, the only mixes that were really deemed not great were lime mixes with Portland at less than 25%. For whatever reason at that point the mortars gained LESS comp strength than a straight fat lime mix that was properly constructed. Permeability, comp strength, and flexural strength were all still acceptable (some higher some lower) with hydraulic mixes and mixes that were gauged with either brick dust or a pozzolan.

It did seem that the higher the temp that the gauging material needed to be fired at the worse the performance. It seemed that this was because C3S was formed at high temps while C2S is formed at firing temps below 1000*C. Portland is fired around 1200*C if I remember correctly. I don't understand the science behind why the C2S is favorable to C3S but it was across the board.

The only problems with gauged materials that I really read about was when they were too hard for either the surrounding material or for the original mortar. Remember, masons have been gauging lime since the Roman era. i believe Pozzolans were "discovered" when the Emperor Claudius wanted the harbour at Ostia to have a break. In significant restoration the desire is to use a mortar that is reasonably water tight, yet permeable, wont damage the units and that later removal wouldn't damage the units either. Compatibility is key an in the past it would have been rare to use a totally no hydraulic lime since most all limestones contain impurities.

Sorry, long boring posts

 

Actually, the problem with portland gauged mortars was that the portland inhibited the carbonation of the lime while not being present in sufficient quantities to provide an acceptable degree of hydraulic action alone, thus producing an uncured (and uncurable) mortar.

 

Right which occured in mixes variously reported as having portland contents lower than 1:1:6, 1:2:9, and 1:3:12 depending study.

 

What 5 pages of 'ideas' of how to match a stupid motar.?
How the heck (ll) did an account get anyone involved with this.?
Give me a break.
Any (ANY) mason would and could have this already written down on paper if not in his mind. We 'do' after-all play with our wares.
5 forum pages. No wonder folks question us.

 

Welcome to contractor talk.

 

The Original question was answered within 4 posts, but it became a discussion on lime mortars. Have a lot of experience with those?

 

Sorry, I did not realized the question was answered. I did not read all the posts.

Without dout, if a man desires a motar to match, it'd be done. But, who does it...? You the agency, organization, public/private owner or do you the so-called mason they happen to call.?
You have an apartment, basement, garage, shed.....Are you a mason or just wanna be. Experiment all you can. Make it a hobby. Make it your life.
What..?, NFL knowledge is gonna feed your family.......

 

The original question and pretty much nothing discussed in this thread had anything to do with matching mortar. You either misunderstood or answered the wrong post.

 

Sorry

 

Nicely done, I was lighting the torch...:jester:

 

<Shrug> no need to fire off. In my experience, typical line masons don't know or care dick about mortar other than if it will stick to their trowel. They can't match, much less design an appropriate mortar, and the reality is that they don't need to. The Masons on this board are not typical line masons and can and should be able to design an appropriate mortar and match existing for repair, and understand the reasons why.

In addition, they should advocate for correct and appropriate mortar design at every opportunity, even when it is not technically in their contract. They will be held responsible, and blindly following an inappropriate specification without a paper trail detailing why the specification is wrong will end up biting them in the ass.

 

<Shrug> no need to fire off.

And therefore you will train/teach every employee, general and customer.
Otherwise......

 

I attempt to educate engineers, architects, and capital letter Masons. Small letter line masons do not need to know the technicalities, they need to know how to put units in the wall.

In most construction fields there are discrete, measurable standards for the materials and processes used, in unit masonry not so much. Combine that with most traditional higher education for engineers and architects focused on concrete with no distinction between it and mortar, and it is an uphill battle.

Over the last 20 years, I like to think I have made some difference, at least the frequency of my calls to defend C-270 on the jobsite have dropped considerably in this area.

 

Definitely visibly, which is why it will not work for light colors. I would still call it a pastel though.

"It seems that the temperature that additives are fired at made a huge difference in their properties."
I agree.

I think modern bricks are not only fired at higher temperatures, but are comprised of different materials (deeper clays and shales). With that, you may well be getting something entirely different than old brick dust.

I like to think that metakaolin is close to old bricks, since it is clay that has been heated, to what I assume is less than 900C. This should be less than the kiln temperature used to make NHL. I cannot find firing temperatures so I cannot positively verify this. The alternative is NHL from purely siliceous limestone, since this has only one phase, belite. St Astier is purely siliceous. I am not sure of others.
Kaolin itself, also seems to provide a bit of a hydraulic set

 

Definitely visibly, which is why it will not work for light colors. I would still call it a pastel though.

"
I like to think that metakaolin is close to old bricks, since it is clay that has been heated, to what I assume is less than 900C. This should be less than the kiln temperature used to make NHL. I cannot find firing temperatures so I cannot positively verify this. The alternative is NHL from purely siliceous limestone, since this has only one phase, belite. St Astier is purely siliceous. I am not sure of others.
Kaolin itself, also seems to provide a bit of a hydraulic set

The colour makes it tough to use the brick dust, unless you could find it from a buff coloured brick. Unlikely.

This metakaolin sounds interesting. 1000*C seemed to be the point that C3S was developed rather than C2S.

At what proportion to the lime would give a compressive strength in and around 400psi? NHL is pretty much unavailable here and i don't do near enough resto to bring it in myself, but if I could get a few dozen bags of this metakaolin it may do me for a while. I'm assuming it doesn't go off on it's own from moisture? It requires the CaOH in order to become reactive? Any change in the mixes appearance using it?

 

In the old bricks, as a rule, the buff colored bricks were fired to a higher temp than the salmons, although both were low by modern kiln temps. The same holds true for modern wood/coal fired bricks like those made on the Mexican border. I am not clear exactly on the desired chemical makeup of the gauging material yet, but I am still reading.

 

Well salmon bricks are just bricks that are too far from the fire to get decent heat. Buff bricks are from white/grey clay.

The different chemicals desired are various, but involve alumina, silica and magnesium as well as the calcium, carbon, oxygen and hydrogen. There seem to be dozens of possibilities and obviously there are very complex interactions. The only chemical that I read about that was undesireable was the C3S, but I have no idea why. Chemistry for me was a long time ago and I didn't do all that well in it anyway.

 

In modern brick making they use different clay bodies for buff and red bricks (or at least add minerals). In old brick firing methods, they were produced from the same clay body, and the only difference was the firing temps in the kiln or clamp.

 

In modern brick making they use different clay bodies for buff and red bricks (or at least add minerals). In old brick firing methods, they were produced from the same clay body, and the only difference was the firing temps.

Not to my knowledge. There are 2 different Clays. a red/orange clay, and a grey/buff clay. The grey/buff bricks contain little to no iron oxides (why they aren't red) which is why they are also used for fire brick

 

Request a visit to a brick manufacturing facility near you. The color of the finished brick has little to nothing to do with the color of the clay body, with few exceptions.

 

i haven't seen a modern buff coloured brick. I'm not talking about the face of the brick. I'm talking about the body of the brick itself. Hanson has a few yellow bricks, but they aren't what I'm talking about. What I'm talking about are the same as old red/orange bricks but they are a grey to buff colour, not yellow. I haven't seen any except in century old houses. I'll see if I can find a picture and see if I can figure out how to download them.