Homebrew mortar Quantity Question

[ML38]

I've been trying to find an answer to this question with no luck. I've decided that I'm going to go with the homebrew method intead of something like HeatStop for mortar.

Plans say you need 3 50 lb bags of mortar for dome. Many people say you end up using more so let's just say you need 300 lbs for the sake of discussion

Does that mean that if I use the 3:1:1:1 (sand,Portland, lime,fireclay) recipe that a single 50 lb bag of Portland cement, lime and fireclay along with 3 bags of sand will yield me 300 lbs of mortar mix?

Thanks
Marc

[david s]

No, the recipe is by volume not weight.

[ML38]

david,

You're right. I knew that but didn't consider it so I did a little research:

Here is what I found for weight per 1 cubic foot of each ingredient.

Fine Mason Sand: 111 lbs
Portland Cement: 94 lbs
Hydrated Lime: 30 lbs
Fire Clay: 130 lbs


Soooo.......if you purchase 1 - 47 lb bag of Portland cement (now I know why it comes in 47 and 94 lb bags, I think) you would then purchase:

167 lbs of sand
15 lbs lime
65 lb fire clay

You end up with 294 lbs of mix which should be pretty close to the weight by volume of the product you are replacing with the homebrew and probably enough for the job.

Does this sound right now?

Unfortunately, you may not be able to find these ingredients in these quantities and will end up with more than enough but still a lot more inexpensive than the premix stuff.

[agrasyuk]

Refratory mortar , the Premix stuff in a 50lb bag that I see on shelf of local hone improvement store is 60$ +tax. Not sure how much will be needed for my build but
300 lbs of that adds up to quite a dollar amount. hence I went with homebrew. So far with 7 rows laid I'm still on first bag of portland, clay and lime .(sand is cheap). I might need to crack open second bag of clay soon though.