On ancient/old ways of mixing mortar

[Phyrebrat]

Hi,

In the early timeline narrative of my WIP I need an ancient pagan society's bones to be ground up and worked into the mortar or a Norman church that is built in the centre of a triple henge. The megaliths have been used to construct the church, and the mortar has this gruesome ingredient.

I'm drawing a blank on research for the process of mortar production for the Middle Ages and can be fluid with the time scale from 1113 - 1300s (in fact the Black Death wipes out the entire parish so it can be as far in the 'future' as 1450.

Does anyone have any credible source ideas outside of wikipedia, please?

Thanks

pH

 

[Kerrybuchanan]

I can't link to it because it's pre-internet, but the house I grew up in had the remains of Norman structures in parts of it and was examined by an archaeological team from University of Leeds at the same time as they were excavating a Roman pottery in our front garden. From memory, I'm nearly sure they referred to lime mortar with horsehair and dung in it. Parts of the structure were wattle and daub too.

 

[Venusian Broon]

It seems that mortar technology advanced with the Greeks and Romans who introduced lime to form lime mortar, then added ash and things to make a mortar that would harden under water. Then we forgot how to set mortar properly and nothing happened till 1824 and Portland cement - when we rediscovered how to do the whole cement in wet conditions thing. So your back at lime mortar only for the time period.

There are of course myths of human sacrifice at the foundation stone - but they usually involve flowing blood and ritual murder, not old bones.

I'd possibly go for - they reduced the bones to ash to mix in their mortar - not for any technical reasons (or perhaps you have a proto-scientist or Roger Bacon-like person that half knows that mixing in ash makes the mortar better?), but for spiritual, mystical or symbolic reasons wants to put the 'souls' of these pagans into the build to 'protect' it? A bit like the sacrifice idea, although I can't really think of it being done anywhere in real life.

Like Kerry says I do believe they did add all sorts to the mortar, like horsehair, so every cement mixer in the mediaeval age probably had a secret recipe of things that they mixed in to the basic lime mortar for various reasons. However the biggest factor was probably they had to use whatever was at hand. Unfortunately I have no research on this to back up these claims!

EDIT: here's a website that talks (once) about using Bone ash as a Pozzolan...

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

 

[Phyrebrat]

Thanks both! I was getting conflicting info on the use of lime which is what I wanted to use because of a plot point and a choice one of the characters decides to make. I don't need the history to say bones were used in mortar, btw, that's one of the McGubbins, just that the early Church converted the Bronze Aged site to a Christian place of worship and although I had the architects use the existing stone ciurcle for material, I wanted to know how they would go about creating mortar.

With Kerry's point about the inclusion of all sorts in the mortar and VB's info on lime (which I was hoping I could use in my ingredients) I'm happy.

Incidentally, I was researching earlier using my iPhone and today as I am off sick, have now been using the Mac and have found the results have been much better in terms of hits (?). Not sure why that should be the case but I've even found a youtube video of a Medieval mortar maker

pH

 

[Ray McCarthy]

Burning limestone / chalk to make lime for mortar is very old. I don't know when they started mixing it with other stuff as a fertiliser.