'soft' firebrick questions, please ??

[smallhagrid]

Howdy Folks.
I was very fortunate to find someone with a big pile of what he calls 'soft' firebricks for a very good price and thus far I am very impressed with these beauties.

They are amazingly easy to work with, which helped me hugely as I needed to fix the replacement woodstove here, which meant making them fit, and they can be cut so easily that it was a nice, quick repair.

Now that the old, nasty stove is out I will soon begin to make the RMH in the central room here.

If anyone here is familiar with these kind of bricks, I hope I can get some advice, please.

The potter I got the bricks from very generously also gave me some clay, hence my query:
Is clay suitable by itself for mortaring/sealing the gaps between firebricks ??

Is there something better ??
(I do have some regular mortar which is, of course, much coarser than clay.)
((I will much prefer if I can avoid buying more stuff, if possible...))

The man I got the bricks from said thay will take whatever heat is thrown at them, and I already see how these may be more resilient after the 'hard' bricks in the woodstove fell to bits during transport on a pickup truck.

I will greatly appreciate any pertinent info anyone will share with me on this subject.

Thanks !!

[matt walker]

Hagrid, you've done very well. Those are the only fire bricks I would use in a build since they are highly insulated. As you've found, they are very soft, so you will need to be careful with banging the fuel into them. Similar to my soft, insulated cast mix, you can just patch any wear spots in the fuel feed area with handfuls of clay over time as needed. A clay/sand mix will make a perfect mortar for those, don't sweat the details too much, you will learn as you go and there's a fairly broad range of what will work. Sounds like you are on your way, I'm glad to hear it.

[smallhagrid]

Thanks Matt !!
I tried searching here just using the trem 'clay' - but the search refused that word...woof !!!

What I have is bags of the clay the potter used for making pottery, and I've never mixed clay up with anything before.
The stuff is squishy and pliable and I can imagine mixing it with water to a soft paste form and squishing that between the bricks to seal them - but I've no idea what sand I would use if I mixed sand into it as suggested...?

Given what I have on hand I will make the burn tunnel and riser all out of bricks, so sticking them together and sealing the gaps seems quite important.

I will greatly appreciate any further education on this topic, please ?!?

Thanks.

[matt walker]

Sure, ideally you would use what's known as "mason's sand", and it is used by masons for mixing with clay, lime, portland, etc, to act as the filler which helps control expansion/contraction and gives the mix some tooth. If you looked at it closely you would see that it is "sharp" so it binds together. So, that's the perfect stuff, but folks figured that out by using whatever they had. I'm sure in the old days folks didn't truck sand all over the place to build their masonry structures. If you use the clay by itself, it will shrink way too much and crack, so you will have to mix it with something. Is there a creek, stream, river, lake near you? You will only need a bucket full of sand, and it can have "stuff" in it, it doesn't need to be perfect. If there is a place that sells bricks, or landscaping gravel, road bed supplies, etc, they will all have sand and often a five gallon bucket is free. Listed price at my local place is $1.50 if you bring your own bucket, but they've never charged me. Last resort is Home Depot or the like, where they actually sell bags for mixing in concrete projects. Good luck.

[Lollykoko]

This is the season when local stores start stocking sand tubes for weight in your vehicle to get you through the snowy season. I buy 4 of these every year, since they are easier to drop to the ground in the spring than to pick up to the truck bed in the fall. Anyway, what I get is normally a 70 pound bag of sharp sand and the cost has been $3 ~ 4 per tube.

[smallhagrid]

Thanks Matt and Lollykoko !!
Where I am living is quite wet, but also very rocky - as such I suspect that collecting sand by the pond will be a poor choice for me.

One good thing about living in Vermont is that the town garages always have a huge pile of sand and one can go and grab buckets of it with no hassles...and after being here for months it is time for me to find that place !!
(Tube sand is also a great idea, should the time & weather not work out for getting some otherwise.)

My lingering question goes like this=>
If I have to choose between watering down the potter's clay to mix it with sand VS. making a mix of mortar and sand...
Is one likely to be better than the other when used in making a brick burn tunnel ??

Thanks Again !!!

[smallhagrid]

[mannytheseacow]

Hi S.H.,

I don't have any experience with building firebrick burn tunnels but I imagine Ernie and Erica know their P's and Q's about this sort of thing and you can probably bet on their advice. Having said that, I wouldn't hesitate to throw a little sand in there for strength. These things are so forgiving and simple. I bet you'll be alright. Just go for it!

[smallhagrid]

Thanks Manny !!
I do plan to jump right into this ASAP.

My hold-up right now is that the floor space for it has a huge side-by-side 'frig standing in it.
Moving that means I need to make a sort of ramp across the top of some nice, steep stairs so I can do this by myself (minus the falling down the stairs part, of course !!!).

After that my only remaining step is to fabricate a support for the bricks on top of the base I'm using - and it will be well under way.

Delay times like this are very good for asking questions.
I've gotten some very good education during this time which I am quite grateful for.

[mannytheseacow]

From your other posts, S.H., it sounds like you've got a very interesting build that is going to take place. I can't wait to see what develops and see some pictures!