36" in Seattle

[ThisOldGarageNJ]

Re: 36" in Seattle

looks great I love the way you did the arch....

cheers
mark

[kebwi]

Re: 36" in Seattle

The first three courses (vertical side-walls consisting of asymmetrical right trapezoids) are totally complete, including notched arch merges. The course of wedges that will transition to the first curved dome course is also complete. No photos, but it's easy to extrapolate in your mind from photos in earlier posts.

Also built some of the pieces of the outer arch for later transport to the site. I find that is it much easier to put multiple bricks together in the basement, then transport them to the site for construction. I did this for the side walls, one of the two inner arches, and now much of the outer arch.

Recalculated and rebuilt my brick placement tool with a hinge. I now have the option of using each version of the tool (the nonhinged version is shown in an earlier post).

Cheers!

[ThisOldGarageNJ]

Re: 36" in Seattle

hey keb,,

Looks like your homebrew mortar is working okay ??

Cheers
Mark

[kebwi]

Re: 36" in Seattle

I guess so. I have no basis for comparison so I don't know if I should stop using it. I'm using 3:2:1:1. I don't know what the refractory or mortar-specific (stickinesss, set-time, etc.) effects are of doubling the fireclay. I don't know if it's a good idea at all.

One concern I have is that my mix effectively reduces the relative quantity of "glue", i.e., Portland and lime, overall, relative to the Pompeii 3:1:1:1. I don't know if that means I've weakened the mortar...but some mortars have a HECK of a lot of sand in them, far far more than Pompeii (or mine), so I assume I'm all right in that regard.

One other thing that should be noted is that I'm using #30 sand, for no better reason than that's what I found at HD and bought and started using before I knew any better. Subsequent discussion with mortar companies have suggested that #50 might be better. I have noticed that my mortar is particularly gritty, making tight mortar joints rather difficult. I don't think I would recommend it, except perhaps for fat mortar pockets where larger aggregate might actually be beneficial of course.

I've also start mixing my mortar with warm water. I don't know how to quanitify "warm" of course, but I shoot for somewhere around the temperature at which it doesn't feel warm or cold on my fingers. I'm not sure what the effects of too-cold or too-warm water would be. I've made mortar with very cold water and I'm not sure what difference there was. I started using warm water simply so my fingers wouldn't freeze, not for any cementary (ha!) reason.

Anyway, charging ahead. I started trimming corners off square bricks for the curved courses. They seem to lean into each other perfectly, so I except that to go fairly well.

Cheers!

[tfasz]

Re: 36" in Seattle

Yeah - it has been a lot nicer to work out of the garage the past month in Seattle. That is what I've been doing too.

Your brick cuts are looking great. Looking forward to seeing your dome start to go up.

[kebwi]

Re: 36" in Seattle

I've been cutting the bricks for the first curved course. Not much else to say, hope the weekend goes smoothly.

[cynon767]

Re: 36" in Seattle

I guess so. I have no basis for comparison so I don't know if I should stop using it. I'm using 3:2:1:1. I don't know what the refractory or mortar-specific (stickinesss, set-time, etc.) effects are of doubling the fireclay. I don't know if it's a good idea at all.

One concern I have is that my mix effectively reduces the relative quantity of "glue", i.e., Portland and lime, overall, relative to the Pompeii 3:1:1:1. I don't know if that means I've weakened the mortar...but some mortars have a HECK of a lot of sand in them, far far more than Pompeii (or mine), so I assume I'm all right in that regard.

I did the same thing, based on what I'd read here and a few other places. Totally unscientific, but from what I know about portland cement breaking down at high temp while fireclay fires to brick-like consistency, I decided to go for it. Some people (including Frances from this place, I believe) have used a mix completely devoid of portland, and simply kept the project meticulously dry until it was fired. I was not so brave, so I merely increased to proportion of clay slightly in hopes of having a more solid fired product than otherwise. Mine is still in the construction phase, but I have total confidence in the strength of the mortar thus far. It has borne my full weight standing on the dome many times now while working on the chimney.

[kebwi]

Re: 36" in Seattle

Second attempt at that last image, which was ridiculously shrunken during the last upload for some reason (some png/jpg discrepancy).

[eprante]

Re: 36" in Seattle

A question about your home brew, specifically about the sand. You mention sand rated at #30 and #50. What is the difference( I am a newcomer to this masonry stuff). Is #50 finer than #30. I am thinking of doing the FB home brew mortar but have questions about the sand. I am planning on doing compound cuts on my bricks, so fine grained mortar is going to be easier to work with. I was originally going to use beach sand (very fine grain). Is increasing the proportion of fireclay going to give a stronger mortar joint.

Sorry if this is too many questions, but you seem to have thought the mortar thing through.

Eric

[cynon767]

Re: 36" in Seattle

The # refers to the screen mesh used to grade the sand. The higher the number, the finer the grain. I tried #20, #30, and #60. The finer stuff was definitely smoother, but I don't know that 60 was really necessary.

[kebwi]

Re: 36" in Seattle

I'm using #50. I think it's fine, except in extremely tight joints (1/16") where I can't get a smooth enough cream at the required thickness (thinness) without it breaking apart. For 1/8" and up, I'm sure my #50 sand based mortar is fine, albeit a little gritty to work with. In fact on the assumption that sand serves the same basic purpose as larger gravel in concrete, the logic seems to be that you want a larger aggregate for a larger overall volume of mortar or concrete. Thus, the larger sand is probably beneficial in some vague way for big fat mortar pockets, like on the outside of the dome up the curved courses, where the mortar spacings between bricks might be half an inch or more. That's my thinking anyway, I really don't know.

As for the effect of increasing the fireclay, as I did, I really don't know what effect that has. I have asked on FB several times and have never gotten really direct answer to the question "what does increasing the fireclay do to mortar"? I suspect no one knows what effect such a change has on the mortar. So long as the mortar still "works", maybe it just really doesn't make any difference.

Cheers!

[kebwi]

Re: 36" in Seattle

Cleaned the mortar from the previous outer-arch construction (no pics, see earlier post), then built a few more pieces of the outer arch and cleaned them up (shown this post).

Cheers!

[kebwi]

Re: 36" in Seattle

I completed (minus arch-merges) the first curved course today! I filled the gaps between adjacent bricks with brick wedges that were scrap from earlier cuts. I intend to continue this practice in an effort to minimize large mortar gaps, but probably only to the extent that I have sufficient scraps. If at some point I run out of scraps of appropriate size or shape, I probably won't intentionally cut up bricks for this purpose. I have a lot of scraps though.

Cheers!

[ThisOldGarageNJ]

Re: 36" in Seattle

Hi Keb...

From the pics it looks like everyting is coming along fine.....

Cheers
Mark

[kebwi]

Re: 36" in Seattle

Yes, thank you. The curved course went up with relative easy, thanks in no small part to the "dispensable" tool. What a fantastic idea.