Refractory in Thailand

[Thailandnotes]

I'm testing out the refractory mortar I bought here. After it had dried for two days, I was easily able to pull bricks apart and crush the semi-hardened mortar back into a fine powder. Normal?

I mixed a new test batch of 2 parts refractory, 1 part Portland. This mixture adhered better to the bricks, produced a strong bond. and dried more over 48 hours. A member who has already built and successfully used an oven here in Thailand suggested this, but I cannot find any reference to mixing the two together. It does not seem to me that the straight refractory mortar can work. I know it hardens after many days and being fired, but the like of adhesion is what really has many searching for clues.

Comments?

[brickie in oz]

Re: Refractory in Thailand

Refractory mortar to me suggests its an all in one product and shouldnt need the introduction of portland cement, portland cement and heat not being best friends at all.

[Thailandnotes]

Re: Refractory in Thailand

That's what I assumed, however, I can't believe it's supposed to set up like it has. 2 bricks mortared together, sprayed, dried under plastic for three days...they can easily be plucked apart, the mortar scraped off with my fingers and turned back into powder without much effort.

[david s]

Re: Refractory in Thailand

Use the home brew mix.

[Thailandnotes]

Re: Refractory in Thailand

Can't find the fire clay.

[david s]

Re: Refractory in Thailand

Any powdered clay should work ok. Try bricklayers clay, it is cheap. A true refractory fire clay is quite expensive, at least where I live anyway.

[Thailandnotes]

Re: Refractory in Thailand

I bought a bag of something here in Thailand.

It is labeled, “Air-Setting High-Alumina Mortar (DryType)”

I’m confused as to what it actually is.

From the Thai company’s website, I found that its chemical composition is 68.5 %Alumina, 27.5 Silica%, and 2 % Iron.

I am confused by these statements in Forno Bravo’s “High Heat Mortar Primer…”

“The site-mixed mortar can be made with standard Portland cement, or with refractory cement, called Calcium Aluminate.”

And

“Make your own mortar, using either fireclay and Portland cement or fireclay and Calcium Aluminate. Fireclay is a heat resistant clay made up of aluminate and silica.”

FB’s on-site mixture is:

1 part Portland cement
3 parts sand
1 part lime
1 part fireclay


How does what I have purchased fit into this recipe.

[david s]

Re: Refractory in Thailand

Try this thread.

http://www.fornobravo.com/forum/f6/r....html#post6202

[Thailandnotes]

Re: Refractory in Thailand

Thanks. I had already bumped into that thread. I'm pretty sure I have a refractory cement, even though on the company's website it is called a "mortar." My question then becomes, can I use the cement I bought in place of the portland in the recipe

1 part Portland cement
3 parts sand
1 part lime
1 part fireclay

At the bottom of the FB primer is a second recipe (with A warning). In the second one the portland has been replaced by calcium alluminate. I need a chemistry lesson.

[david s]

Re: Refractory in Thailand

Portland cement is calcium silicate as opposed to calcium aluminate cement that is used for high temperature refractory mortars. If your product is labelled "mortar" then it probably contains calcium aluminate cement mixed with high temperature aggregates. As the oven will not get up to high temperatures (500 - 1400 C) then these aggregates are not necessary and an expensive overkill.