I know it is not exactly a timber frame question but there will be a timber frame set on top of it. I was planning to lay up a foundation of my local, free bluestone as opposed to hauling in a cement mixer and pump truck to do a pour. I have been contemplating using a lime mortar instead of the commonly used Portland cement due to the positive research results I have gotten from advocates of lime mortar, not to mention it is more traditional. Does anyone have any experience with lime mortars that might be able to help me get started?? Sources for quality lime? Recipe for slurry and finished mortar?Techniques for mixing and applying? Possible drawbacks to me opting to use lime instead of Portland?? Perhaps a Portland-lime mix? I would like the contrast of the white lime mortar in relation to the gray color of my Catskill bluestone. As far as techniques, I have read that back in the day the masons would mix a big batch of lime mixed with a high proportion of water, creating a soup-like consistency(called "lime slurry"). They would use this slurry when they needed to make mortar by scooping out the slurry and mixing it with some local sand. The lime slurry would be made in big batches and left to sit tightly covered and it would actually improve with time as long as it is kept airtight. Does this sound about right?? To make this slurry and have it be able to sit around a bit, suits me well in this project.I am just stating some of the details that have come to me in research, but I have absolutely no actual experience with lime mortar, so I am just wondering if anyone might have some guidance for me in this project?

Virginia Lime Works does a great presentation and has been a very good source of information. Unfortunately I never got to the tuckpointing that I intended to do this year but I will be going the lime route as well. Avoid the temptation to use agricultural lime as it has likely been fired to higher temperatures that remove the desireable properties of hydraulic limes. As well, stay away from Portland Cement if you are looking for the self-healing properties of lime products. I do not have enough experience to comfortably recommend any particular books but I would contact VLW and also look at the several other firms that are advertising product (not the cheapest stuff in the world) and also try posting over on the Preservation Trades Network (ptn.org) to see if you can get some info there.

Hi TB:

Just a word about using traditional lime mixtures, I have a fair amount of experience in this department because our displays of timberframing required the use of traditional mixtures to set the foundations stones in place.

Traditional mixtures are fashioned using "unslacked lime". The slacking is very dangerous and can easily burn down wooden structures that may be adjacent to the mixing area. Very much heat is generated in the process and should be monitored by someone that is knowledgeable.

It is vey hard to obtain unslacked lime now, so in its place I would use this mixture,

Slack some agricultural hydrated lime in water, until you have a thick slurry, then let it set for a few days and remix.

Take 3 shovel fulls of good sharp mortar sand, add 1 shovel full of the slacked lime and 1\2 shovel full of "white portland cement". This will give the mixture alittle hardening effect but not too much and will look and feel like the historical mixtures did. It should turn pure white when dry.

If you can obtain the unslacked lime and slack it carefully, then you can use 5 shovel fulls of good sharp maonary sand, and 2 shovel fulls of the slacked mixture this will give you the true historical mixture used in the antique structures sprinkled across the country

NH

Hi there TB:

Just to further my comments about lime mortar, I like yourself appreciate the traditional look of the lime mortar joint against the blue limestone. Nothing in my opinion looks any more hideous than the gray maonary cement look that modern mixtures give stone wall construction. What I have done in the past and seems to work out well is to use a good quality portland cement mixture to lay the wall with but rake out the joints to a depth of 1" or more and then use a good lime mixture as I described above to fill out and finish the joints with a small pointed trowel.

I hope this helps you out, it seems that you know what you want but need help geting there, and getting that look.

NH