# Historic Mortar Mystery



## matthewkantar (Aug 8, 2015)

Below is a link to the original specification for the mortar used to construct my 1909 brick factory. I would like to use the same mix to do repairs, but cannot make heads or tails of it. 

The text reads: "For each cubic foot of finished mortar use one-third (1/3) of a barrel of lime, four bags of portland cement and the balance of sand, and not to exceed the finished quantity of one cubic yard."

I assume when the architect writes "one cubic foot" at the beginning, he meant "one cubic yard". A barrel of lime back then was either a "small barrel" of 180 pounds, or a "large barrel" of 280 pounds. I assume the cement was in 94 pound, one cubic foot bags as it is today.

When I tried this out I got either a "big barrel" 3:1:21 mix by volume, or "small barrel" 2:1:20.5. The resulting mix is so sandy it won't stay on the trowel no matter how dry or wet it is.

Maybe the architect was a blow hard and the masons ignored him? Any insight would be greatly appreciated.

Matthew


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## Tscarborough (Feb 25, 2006)

Small barrel would equal 3.6 CuFt (assuming a dry hydrate) or 5.6 CuFt for a large barrel. Also assuming the CuFt bag of portland ( safe assumption), then it works out to:

Small barrel: 1.08 CuFt lime/4 CuFt Portland/22.92 sand or 5.08/22.92 or 1 part cementious material to 4.511 part sand. No good.

The big barrel: 1.68 CuFt Lime/4CuFt Portland/22.32 sand or 5.68/22.32 or 1 part cementious material to 3.92 parts sand. Still high, but workable.

Remember they were not using C-144 masonry sand, it was probably screened to max 1/4" to dust. That is what The University of Texas and Camp Mabry use for historical repair, more or less (for the type of sand, not the volume). I also doubt that the architect was very specific with his mortar specification, it was probably more of a guideline. Do you have a scan of the actual specification in full?


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## Tinstaafl (Jan 6, 2008)

Tscarborough said:


> Do you have a scan of the actual specification in full?


Here's the pic he tried to link:


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## hdavis (Feb 14, 2012)

Just to double check, I'd go to archive.org and look a builder's or architect's reference from that time - it should tell you what was common for bags, etc at that time.

I probably already have it, I'm just too lazy to find it.:sad:


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## Tscarborough (Feb 25, 2006)

It was more common for cement to be supplied in barrels, not bags, same as the lime. The specification does at least make clear that the lime was a dry hydrate, not a putty. The use of a 1 CuYd mixing tub is kind of strange though, as that is a lot to mix by hand and even more to utilize within an hour. Methinks concrete engineers were writing mortar specifications even then.

Send a mortar sample out for reduction testing, they will give you both a sieve analysis of the sand and the ratio used as opposed to specified.


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## fjn (Aug 17, 2011)

TScar. is one of the more knowledgeable members on this forum regarding mortar. As he mentioned,you do not know if it was a dry lime or putty. This essay sheds some light on the impact of one vs. the other.



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


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## FrankSmith (Feb 21, 2013)

matthewkantar said:


> Below is a link to the original specification for the mortar used to construct my 1909 brick factory. I would like to use the same mix to do repairs, but cannot make heads or tails of it.
> 
> The text reads: "For each cubic foot of finished mortar use one-third (1/3) of a barrel of lime, four bags of portland cement and the balance of sand, and not to exceed the finished quantity of one cubic yard."
> 
> ...


What type of carpentry work do you so? Do you own the business or work for it?


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## Tscarborough (Feb 25, 2006)

That scan shows him to be very specific, the difference between then and now is that they also have to reference standards to justify their spec. They had a lot more latitude then. Do you have any pictures of the existing mortar and any tuckpointing?


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## hdavis (Feb 14, 2012)

Possibly helpful info from around that time - 1 barrel of cement = 4 bushels of cement ~= 380 lbs of cement. I didn't find a reference to bags of cement, but that could take a lot of looking to rule it out.


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## Tscarborough (Feb 25, 2006)

My period reference, "Handbook of Concrete Construction" gives a barrel weight of 376 pounds, or equivalent to 4-94# sacks. When shipped in sacks it was in burlap/paper sacks of around 94#. Circa 1913 and reproduced until the 1940s. My Pops gave me his reprint, dated 1943, that was a required textbook for his Civil Engineer classes in the late 1960's.


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## Fouthgeneration (Jan 7, 2014)

A 94 lb bag of Portland Cement is equal to a 1/4 barrel of P cement, P cement is STILL wholesaled by barrels or tons, "pigs" the tanker trailers used to haul P cement are approximately 800 bbl, (they aren't ever filled full)

the foot is a typo---the man meant cubic yard, then all the proportions are copacetic....

the grading of the sand particles would of course effect the interstitial volume available for the mortar paste to fill, thus effecting the number of cubic feet of sand needed to produce the cubic yard of mortar.

the biggest issue i think one would have with clamp style brick kilns is getting/keeping them dry enough so they didn't suffer steam explosion damage during firing.

A 1905 Ohio lime essay had barrels at 185 lbs net weight for hydrated lime, the mortar recipe won't by very 'fat'.

Note the prohibition on adding water to mortar and the throwing away any 61 minute old mortar, that is a big crew to lay over 1000 brick a hour steadily....

I dread hoeing a 3 cubic foot batch by hand... I wouldn't want to meet the laborer who hand mixed DRY a yard every hour at the tavern or back alley.


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## matthewkantar (Aug 8, 2015)

Wow, I guess I came to the right place. Thank you all for the helpful info. I believe that i have attached a photo of the mortar Tscarborough asked for. I have the full specification for the building, but the section above is the only place mortar is mentioned.

Fourthgeneration's and Tscarborough's dads reference info stretches the possibilities for the weight of lime in a barrel to 380#. The info I had was from standardization that took place shortly after the factory was built. If the mix is based on 380#, it seems like it will be much more workable and similar to the material on the structure.

I purchased white Portland cement thinking the historic mortar was nearly white, that was a mistake, the resulting test mixes are blindingly white, even with gold-ish mason sand.

FrankSmith, I am a sole proprietor, I mostly build work for artists.

Matthew


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## Tscarborough (Feb 25, 2006)

That looks like a coarse sand, low binder mortar.


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## Fouthgeneration (Jan 7, 2014)

My mistake, I thought you working on a kiln not a factory building...

Early Portland lime mortars tended to be over lean as the Portland Cement would give very high break test #, but the loss of work-ability of the harsh mixes resulted in leaky and torsionaly weak walls.

with clean graded sand and potable water the mix given could test over 2500 PSI.

Is the building full of settlement cracks? I. E. is the mix is 'self healing'.


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## matthewkantar (Aug 8, 2015)

Not sure what you mean by "settlement cracks". The foundation is extraordinarily stout, and some parts of the building rest on living rock. Most of the cracks in the building are from rusting lintels jacking the structure up above the windows.

Matthew


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## Tscarborough (Feb 25, 2006)

What he means is autogenous healing, but a mortar with those specifications will not exhibit much, if any. The expansion of the brick will close those without any autogenous healing needed. Autogenous healing is a process in which high lime mortars are able to bridge microscopic shrinkage cracking and actually heal themselves by extending the crystalline structure across the crack plane.


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## Fouthgeneration (Jan 7, 2014)

Love to know what the difference between "living" rock and other types....:jester:

Just about any high strength mix would work, add a little black or gray color and maybe a little buff for ~100 years staining. The biggest long term issue remodeling multi wythe brick buildings is lowering the average temperature of the structure so it suffers freeze thaw attacks formerly heated wythes, eventually leading to failure.

Other threads here address that issue.


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## dom-mas (Nov 26, 2011)

If you are finding the mix too white, try adding 1/4 cup of buff or light ochre mortar dye for each bag of cementitious materials and see where that gets you. Add or subtract until you get a decent colour, up to 10% of the cement, but that is usually WAY too much for this sort of an application. If you aren't worried about getting a real close match and just want to tone it down a little, use half the amount of white portland and substitute the other half for regular Type I/II. Make sure not to tool the joints when the mortar is wet, wait until it's thumbprint hard. Other techniques are to use wood jointers instead of steel and to hit the joints (literally beat them with a stiff brush) after tooling, this will bring out the aggregate


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## CarpenterSFO (Dec 12, 2012)

Any chance the masons would have looked at that spec, dismissed it as clearly erroneous, and just made their normal mortar? That little sample looks a lot fatter than anything that would get cooked up with those numbers, doesn't it?


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## fjn (Aug 17, 2011)

Fouthgeneration said:


> Love to know what the difference between "living" rock and other types....:jester:




My take on living rock,he means bed rock or out cropping rock.


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## fjn (Aug 17, 2011)

Here are some photos of the sand pits supplying the sand for oil fracking. Also,that sand volume is just the tip of the iceberg compared to the volume in the tri state area.



Enjoy !

https://www.google.com/search?q=san...oTCMHprcGYp8cCFQVaHgodzP8F9Q&biw=1366&bih=643


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## hdavis (Feb 14, 2012)

Fouthgeneration said:


> Hdavis: so you'll admit round shapes tend to return to rubble faster than shapes with parallel faces shapes when stacked up.... why wouldn't apply on a micro scale?


That post was a comment about how regional esthetics vary. What looks out of place in one area can be the norm in another.


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## matthewkantar (Aug 8, 2015)

Here are some photos of my first masonry job. The aim is to repair the elevator/stair penthouse that rises above the roof on my 100 year old factory. It is about 18' X 24'. The first two pics show how it looked a week ago. The corner closest to the camera in the first photo has a scupper that drains the roof, it was leaking into the wall.

We have very hard freezes here by the way.

The bricks in the whole area under what I think was torch down roofing material were crumbled. The second pic shows a nasty repair from some time ago, complete with chunks of CMU cemented in with glass-hard mortar. The south and west faces were repointed at some time, but only an eighth of an inch deep, and with hard mortar.

The third pick shows what I am up against, only one course of brick (out of four) remain in parts of the corner, entire parapet on one wall is demolished. I am saving as many brick as I can. I have several thousand additional brick for this and other repairs, salvaged from an addition removed from the building a few years ago.

Enjoy, Matthew


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## hdavis (Feb 14, 2012)

Thanks for the pics!


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## dom-mas (Nov 26, 2011)

Oh dear. I wouldn't worry about exact matching, just get it rebuilt and sealed up again before winter. Use a type O, 2 parts lime, 1 part portland (OPC...Type I/II...GU whatever they call it in your neck of the woods) and 8-9 parts coarse sand and rebuild it. 

What's the end game for this building?


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## matthewkantar (Aug 8, 2015)

I am not being all that fussy with this, but the front of the building has tightly spaced hard(er) faced bricks, and I want to be able to repair it right. The penthouse is good practice. This structure can be seen from the ground, but looks don't matter too much. Most of the brickwork has lasted 100 years with near zero maintenance, i like to give it 100 more.

Matthew


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## Fouthgeneration (Jan 7, 2014)

Dom-Mas: @ 61? I suggest you take a magnifying glass to work tomorrow and report back... regarding sand particle shapes.

The exact ratio of globe to cube would be (1/6th pi)~0.524.

but how would the next layer of balls ever keep from rolling into the corner, the next layer of particles would stack into the valleys between the lower or higher plane....thus lowering the void to solid ratio.

Even in just 2 dimensions the 90 degree matrix is far from the greatest density.
Hdavis, field rock fences exist as moments to clearing marginal farm land by very very cheap labor. Cutting hard rock for common construction is mostly a industrial age occurrence.

In my part of the state, stone fences weren't used because wire and wood had become much cheaper and the rocks fewer then out East


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## dom-mas (Nov 26, 2011)

Fouthgeneration said:


> Dom-Mas: @ 61? I suggest you take a magnifying glass to work tomorrow and report back... regarding sand particle shapes.


Done it many times


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## fjn (Aug 17, 2011)

dom-mas said:


> Done it many times







:thumbsup::thumbsup:



I bought a 20 x jewelers loupe on ebay for less than $3.00 for that purpose. Works great,makes the grains look like boulders.:laughing:


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## matthewkantar (Aug 8, 2015)

So thanks for all the help, Finished the job up in October. Here are some pics of the copper scupper I built, and the finished masonry.

Matthew


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## hdavis (Feb 14, 2012)

Pics?


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## matthewkantar (Aug 8, 2015)

Sorry, I thought they were attached. 

I tried uploading them several times now, they don't want to go. Will try again tomorrow.

Matthew


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