why are so many log buildings hewed on two sides?

[DonW]

Slaking an extended time is new to me. Since I've never had much prospect at even getting my grubby hands on any reliable quicklime I never did look much into the slaking process. No, I only know of two time related elements of lime processing, letting the putty stand under water for up to 40 years, (a form of slaking?) and the lime and sand mix standing some months just prior to use, either as a mortar or for pointing up, so that would be somewhat similar to use in chinking log walls. 

When I began going through your article my first thought was this tabby is something like tadelak which is common in North Africa. Could it be that the processes are related? Further on in the article the distinctions were more clear but it seems obvious that the origins predate use by the Spanish and are African, a place where different plastering and similar construction forms are highly varied and developed. 

[Tom King]

I've bought every book I could find on Lime for masonry, and plaster.  I reread parts of one that was reprinted from French by a guy who tested several versions in 1818.  They knew that it absorbed CO2 from the atmosphere, but called Carbon Dioxide    Carbonic Acid.  He went into saying the different theories of different methods seemed to be written by people who believed the way they had been doing it was the best way, but he did his testing because he could never find any evidence that anyone had done actual comparisons before.

He said that the putty made directly from Quicklime had a higher initial adhesive strength, but beyond that, I don't think it lasted any better.  The trouble with any kind of testing is that it would need to be exposed to the elements for at least a couple of centuries, before you really know.

A book I have from the early 20th Century, has a photograph of workers in all white clothes, and cute white hats screening Hydrated Lime from bags into a large vat.  They mixed it ahead of time on the job, but didn't give any recommended amount of time.  I think that one said a couple of weeks, but I have a hard time keeping all the different sources of information clear on stuff I read years ago.  I just came up with something that works good for me, after Virginia Lime Works did me a favor, and went out of business, forcing me to learn more about it.

In some other book, it said the putty needed to be made 3 months ahead of when it was used.  That's what I've gone by, and try to keep some in 5 gallon closed buckets on hand.  I can't tell any difference between 3 months, and 3 years, but there is a Big difference between anything mixed with putty, versus buying anyone's dry mix in a bag.

I believe the Type S, sold by Graymont under Western brand, is pretty close to what the Romans used.  They just dug it up from being processed for them by a volcano.  Some people say humans forgot how to many concrete between the Romans, and the mid 19th Century, but the Romans didn't really know how to manufacture it.  They just dug up what worked.

[DonW]

My assumption was that quicklime form was really the only option until relatively recent industrial and logistical alternatives were available. 

[Tom King]

I believe that's right.

[DonW]

A fanciful representation of the basic process we are going on and on and on about. 
Les feux de Guédelon - saison 1 - épisode 4 - YouTube

[Tom King]

Here's another one, and probably a represents the way it was done here, most of the time.  There were not too many Lime Kilns in this part of the country.  The only one I know is up near Lexington, Va.

There are Many places around the world named Limerick.  This is called burning a Lime Rick.

Building George's House: Lime Rick Burn - YouTube

[Don P]

Eric, sorry, we've wandered, feel free to bring us back around any time.

Lime kiln road is on my way to work from here but the kiln is long gone. I'll try to find and post a pic of one not too far from here built near an old Irish style brick mansion. Many old iron furnaces were last used to burn lime after cold blast went to Bessemer iron, but most limestone here was small rick burns both for building and soil sweetening from what I can tell. Dad remembers digging in the marl pit at home in eastern NC for field dressing when he was a boy.

The volcanic ash the romans used in their opus caementicium, cement work, was replacing part or all of the sand. Other than that it was a mix of quicklime and aggregate, which for them was usually rubble, placed, rammed in and the cement paste was poured and tamped. Vitruvius in his "Ten Books on Architecture" called out a 3:1 mix of lime to sand ("pit sand", volcanic ash) for most work, 2:1 for marine.

From my understanding they learned to burn lime and make plaster centuries earlier when trying to mimic Greek building. The tuff that was more readily available to them as a building stone is not particularly pretty, so they began experimenting with plastering over the rough coarse stone. Plaster itself is prehistoric, probably limestone in a fire ring that burned, it rained, and a workable paste was formed. There's all grades on the way to "ideal" but many that are more or less serviceable.

They had a good understanding of what they were doing. In the dome of the Pantheon (the 2,000 year old, largest unreinforced concrete dome in the world) they lightened the dome as it rose to lower the hoop stress, thrust, by going from 19' thick using brick and dense tufa aggregate at the base down to 5' thick and light tufa and pumice aggregate to make lightweight concrete by the top. Aside from the thickness difference they had cut the density of the concrete itself in half from base to top. That building is really a study in some pretty complex engineering with relieving arches and buttressing that foreshadows later cathedral work but they had concrete down by the time of Hadrian.

[DonW]

Not far from where I lived in holland there is a church tower built with this tuff stone which was a common enough material in the Middle Ages. It really is a but ugly material and's understandable that anyone would want to plaster it. If plaster wouldn't have been around already, this would have been a reason itself to invent it.

[Don P]

I had to review a video I have on Greek and Roman construction to get some of this sorted out and figured it might be of some historic interest.

The Romans learned stone masonry construction from the Etruscans who learned from the Greeks. This was dry laid ashlar (coursed) finely fitted rectangular stonework held together with iron clamps (I've seen examples of lead pours into keys as well). It was highly skilled work as the stones had to be perfectly smoothed for full bearing to avoid cracking over high spots in large structures. The Romans plastered over their ugly stone to imitate marble.

The next development was to apply a thin layer of the same plaster as a lime/sand mortar between stones to allow less well fitted stones to be used. This sped up construction and sealed the joints.

This works fine, lime plaster is air setting, CO2 from the air hardens the hydrated lime back to calcium carbonate, limestone. But, if you try to cast a large mass of plaster the surface hardens and seals the core from the air and it never fully hardens.

About the third century BC they discovered, or rediscovered, that using volcanic sand/ash would harden to a solid that was 5 times stronger than the regular lime/sand mortar. The silica in the pozzolana combined with the hydrated lime to form calcium silicate hydrate which needs no air or CO2 to harden and in fact can set underwater. That compound is what comprises ~50-70% of modern portland cement. The large aggregate in roman cement is broken bricks and tiles, chunks of rubble and stone, and broken amphorae.

As the technology advanced they first built uncoursed fitted stone walls to form opposite faces of a wall, as forms, and poured in mortar, tamped in rubble, repeat in layers till full, opus incertum.

Next they laid up the walls with premade small diamond shaped stone blocks for the facings and filled with concrete as before, opus reticulatum. Less skilled labor (slaves and unskilled workmen). They were conquering more territory and building vast infrastructure.

About the time of Vitruvius 1st century BC they began using terra cotta bricks, mass production. This evolved from experimenting using roofing tiles in wall construction. The square bipedales, 2' square, were cut diagonally into triangles, laying a running bond with the points of the triangles facing the core of the wall, excellent toothing! and pouring the core. Very fast, looks good, much of the work is low skilled.

Going back to opus incertum something else was going on. They had the precisely fitted stone arch figured out but it took lots of highly skilled labor. They had figured out the tied wooden truss for spanning large buildings without rows of internal columns but wood was subject to decay and insects. By extending the arch they could make barrel vaults but the work of fitting that much stone was extremely time consuming. If they wanted a crossing vault building a groined vault in stone is a bear. Wooden formwork is fast and making groined vault centering forms is pretty easy. Pour concrete over the forms and Bob's your uncle. In 193 BC they needed a new trans shipment facility in Rome alongside the Tiber river and built a warehouse that had 50 barrel vaults facing the river for 1600 feet. The vaults stepped up the slope for 200' and were crossed by I think eight 1600' long barrel vaults that ran the length of the building. At each of the steps up the slope the vaults formed an eyebrow window that daylighted the interior. About 300,000 square feet under roof, 2 centuries before Christ! Porticus Aemelia.

As you climb the slope from the warehouses towards the city there is a mountain of broken amphorae rubble. The capitol was an importer, they had nothing to export but soldiers, politicians and war. The shipping jugs were one way containers and used as aggregate, except for the olive oil jugs which were too oily for construction so they threw them out back and kept the front yard looking good.

The brickmaking opus testaceum (tes-tock-eee-um) period really took off around 100 AD. They were making them by the millions and branched out into hexagonal floor tiles, terra cotta water and sewer pipes and rectangular heating tubuli, gotta keep the big bath houses warm. The bricks were stamped with the maker or legion (for military construction) and emperor's name. If you can find a stamp you can date the building.

A really interesting series of lectures from Stephen Ressler, a West Point professor of engineering.

[kantuckid]

Back on tulip poplar log walls- The modern log home industry is often located nearby a plentiful supply of those trees as the mostly replaced the American Chestnut after the blight event. They tried and now avoid then due to checking as it's poor customer relations overall not that they don't function OK structurally. In historical hewed logs houses thats a whole nuther thing. They avoid the poplars and go for some type of regional pine with a handfull of niche market oak & cedar logs walls. 

[DonW]

Once I picked up a load of lime flour and the shop had a partial bucket of a kind of flaky baked clay shards, a byproduct of soft baked tiles or something similar they called "graffel" which I got for experimenting. The shards were small maybe 1/8',  flat and very sharp edged also very light in weight. I used them for agrigate in a poured lime floor, the extra  I dumped out back on the ditch so I was able to observe how it set. This material hardened more than other lime surfaces and makes an excellent floor. A lime floor like this needs no expansion joints and cracks are inconsequential because lime has its self-repairing character. The floor, subject to periodic flooding in times of heavy rain dries almost immediately, never pooling and even continues to harden, the water in fact has a positive effect. 

[NCEric]

Eric, sorry, we've wandered, feel free to bring us back around any time.

Wander away as far as I'm concerned!  It's all interesting, and it seems like the original discussion had a very fair opportunity.

[rjwoelk]

Here i thought "you put the lime in da coconut "

[DonW]

Hopefully there is a route back. I thought maybe we Might be on the way once DonP brought up the stone chinking but I'm confident about getting there. It's all somehow related and squaring up logs with axes is more interesting to me anyway. I mean you could just as easily ask why are mortared stone walls most often made with a flat side.

Eric, sorry, we've wandered, feel free to bring us back around any time.

Wander away as far as I'm concerned!  It's all interesting, and it seems like the original discussion had a very fair opportunity.

[Sedgehammer]

I had to review a video I have on Greek and Roman construction to get some of this sorted out and figured it might be of some historic interest.

The Romans learned stone masonry construction from the Etruscans who learned from the Greeks. This was dry laid ashlar (coursed) finely fitted rectangular stonework held together with iron clamps (I've seen examples of lead pours into keys as well). It was highly skilled work as the stones had to be perfectly smoothed for full bearing to avoid cracking over high spots in large structures. The Romans plastered over their ugly stone to imitate marble.

The next development was to apply a thin layer of the same plaster as a lime/sand mortar between stones to allow less well fitted stones to be used. This sped up construction and sealed the joints.

This works fine, lime plaster is air setting, CO2 from the air hardens the hydrated lime back to calcium carbonate, limestone. But, if you try to cast a large mass of plaster the surface hardens and seals the core from the air and it never fully hardens.

About the third century BC they discovered, or rediscovered, that using volcanic sand/ash would harden to a solid that was 5 times stronger than the regular lime/sand mortar. The silica in the pozzolana combined with the hydrated lime to form calcium silicate hydrate which needs no air or CO2 to harden and in fact can set underwater. That compound is what comprises ~50-70% of modern portland cement. The large aggregate in roman cement is broken bricks and tiles, chunks of rubble and stone, and broken amphorae.

As the technology advanced they first built uncoursed fitted stone walls to form opposite faces of a wall, as forms, and poured in mortar, tamped in rubble, repeat in layers till full, opus incertum.

Next they laid up the walls with premade small diamond shaped stone blocks for the facings and filled with concrete as before, opus reticulatum. Less skilled labor (slaves and unskilled workmen). They were conquering more territory and building vast infrastructure.

About the time of Vitruvius 1st century BC they began using terra cotta bricks, mass production. This evolved from experimenting using roofing tiles in wall construction. The square bipedales, 2' square, were cut diagonally into triangles, laying a running bond with the points of the triangles facing the core of the wall, excellent toothing! and pouring the core. Very fast, looks good, much of the work is low skilled.

Going back to opus incertum something else was going on. They had the precisely fitted stone arch figured out but it took lots of highly skilled labor. They had figured out the tied wooden truss for spanning large buildings without rows of internal columns but wood was subject to decay and insects. By extending the arch they could make barrel vaults but the work of fitting that much stone was extremely time consuming. If they wanted a crossing vault building a groined vault in stone is a bear. Wooden formwork is fast and making groined vault centering forms is pretty easy. Pour concrete over the forms and Bob's your uncle. In 193 BC they needed a new trans shipment facility in Rome alongside the Tiber river and built a warehouse that had 50 barrel vaults facing the river for 1600 feet. The vaults stepped up the slope for 200' and were crossed by I think eight 1600' long barrel vaults that ran the length of the building. At each of the steps up the slope the vaults formed an eyebrow window that daylighted the interior. About 300,000 square feet under roof, 2 centuries before Christ! Porticus Aemelia.

As you climb the slope from the warehouses towards the city there is a mountain of broken amphorae rubble. The capitol was an importer, they had nothing to export but soldiers, politicians and war. The shipping jugs were one way containers and used as aggregate, except for the olive oil jugs which were too oily for construction so they threw them out back and kept the front yard looking good.

The brickmaking opus testaceum (tes-tock-eee-um) period really took off around 100 AD. They were making them by the millions and branched out into hexagonal floor tiles, terra cotta water and sewer pipes and rectangular heating tubuli, gotta keep the big bath houses warm. The bricks were stamped with the maker or legion (for military construction) and emperor's name. If you can find a stamp you can date the building.

A really interesting series of lectures from Stephen Ressler, a West Point professor of engineering.

2 things.
1. How do you find time to work? You have a vast knowledge of so many topics and the time/study to learn all of this, plus work. You are a valuable resource to the forum!
2. I think the concrete they made is still getting harder to this day and we have only just now figured out how they made it. I think I remember reading or watched a show on it.  

[DonW]

Exact composition  and process for Roman cement is still lost. 

https://unews.utah.edu/roman-concrete/

[Sedgehammer]

Ahh k. That's the exact same article I read. Thanks for posting that. I had forgot that part on it. 

[firefighter ontheside]

I just returned to the station from a house fire.  It was an old 1800's log cabin which was hewed flat on both sides.  The outside was sided with old asbestos tile siding and then had vinyl put up over that.  I'm not sure what was on the inside, because the fire had been burning for a while before we got there.  I imagine that it had paneling.  It was a shame to see it go up in flames.  Could have been really neat restored to former glory.

[Old Greenhorn]

Man, I always hated the ones where we had to go through 3 layers of wall to find the fire. We did an old hotel fire (late 1800's original construction) where we had to open 3 different ceilings to get into the void space.  That was an all nighter and took a lot of gear out of service for repair. We were cutting scuttle holes in the floors upstairs to get the water weight out of the building and filled every saw chain with old carpet. Walls over other walls, a mess and a total loss.
 Had another one, small farmhouse type (around 1860) that had three additions that met in one spot where the electrical service came in, which is also where the fire started (10KV backfeed into the panel) and blew the fire up the wall. Those old timbers took it hard and it was a bear to expose and wet it all down. We were worried about what we might cut and bring a roof down or have it shift. We actually saved that house and I pass it often thinking of that February night during a heavy wet snowstorm when I was the only guy on scene trying to knock that thing down. 
 Sounds like you lost that one in spite of the log construction? I am guessing there wasn't much of a foundation to save either? 

[firefighter ontheside]

As near as I could tell it was a rubble stone foundation with sort of a crawl space.  Floor joists were hewn logs too.

The second fire of the day was a mobile home.  It was not made of any kind of logs.  Barely had any wood in it at all.

[DonW]

As near as I could tell it was a rubble stone foundation with sort of a crawl space.  Floor joists were hewn logs too.

so much for my theory on egoism. It's like I always say, squaring up with axes is just plain fun, that's it. 

[Don P]

I swung by the old lime kiln on our way home this afternoon, it's grown up more, I barely missed missing it  :D


 

My understanding of this type is the limestone was broken up into fist sized chunks and loosely loaded into the open top of this furnace. It is built into the bank and the top is at ground level above.

This is where I'm not sure but I think it was fired through this hole and the draft carried the flames and heat in and up through the limestone. After it cooled the burnt quicklime was raked out through this hole. I think it is actually a little taller opening, it has just partially filled in over time. But... some of these were fired by layering limestone and fuel wood together and igniting that, if that is the case this is just the air intake and burnt lime discharge. Looking at it now, I'm kind of leaning that way, I see no smoke marks around this opening and that is a timber header over the opening.



 

This is the nearby house I'm sure the kiln was built for. There was a young family living there about 10 years ago and working on it, it looks unoccupied again  :-\

[DonW]

I burnt- maybe an overstatement- some plaster I'd hauled off, slaked it and mixed in a mason jar then forgot about it moving on to figuring out ratios for clay plaster. Checking recently the slurry'd dried, bonded and hardened good. I guess lime is reusable, the theory, reversing the original reversion of the calcium equation. 

[Don P]

Yes it is, you just restarted the lime cycle by going back to quicklime. Cool 

[DonW]

You know, I've heard stories of these poor saps manning the lime kilns 24 hours a day who've fallen asleep atop the kiln where the fuel is fed and rolled in. No doubt more myth than reality based purely on the suggestion of a set-up like that.