Cementing the bricks question

[stonecutter]

Re: Cementing the bricks question

It seems like you have to consider it a type of aggregate until it is fired at high enough temps to change it to have true binding qualities.

[Tscarborough]

Re: Cementing the bricks question

Old school masons around here add water to the straight fireclay to make a slurry, then dip the firebrick and set them. Only for indoor fireplaces only though. I have seen very old fireplaces that were still in good shape using this method too.

[Campmaki]

Re: Cementing the bricks question

Old school masons around here add water to the straight fireclay to make a slurry, then dip the firebrick and set them. Only for indoor fireplaces only though. I have seen very old fireplaces that were still in good shape using this method too.

I went the home brew method of 3,1,1,1 and it was really rich. I buttered both the brick that was laid already and the one in my hand. Wondered if I would need a support near the top, but even the brick in the last 5 courses held without shoring of any sort. I also added a very small amount of liquid sodium silicate to each pail full I mixed.The place in Minnesota were I purchased the clay said this was the only addition needed to make it true refractory mortar. As the oven is used it will get harder and harder because of this addition. We will soon see.

[Campmaki]

Re: Cementing the bricks question

Just something else to ponder. Is mortar used to hold units together or to hold them apart?

[stonecutter]

Re: Cementing the bricks question

Just something else to ponder. Is mortar used to hold units together or to hold them apart?

Out of the choices you present, holding the units apart wins. But mortar doesn't serve a one or two dimensional purpose. Mortar also functions as a leveler and as a gasket to keep out water intrusion. It is not merely 'mud' and proper mix design and understanding the full scope of mortar function is commonly overlooked by even professional masons.

[stonecutter]

Re: Cementing the bricks question

I went the home brew method of 3,1,1,1 and it was really rich. I buttered both the brick that was laid already and the one in my hand. Wondered if I would need a support near the top, but even the brick in the last 5 courses held without shoring of any sort. I also added a very small amount of liquid sodium silicate to each pail full I mixed.The place in Minnesota were I purchased the clay said this was the only addition needed to make it true refractory mortar. As the oven is used it will get harder and harder because of this addition. We will soon see.

I would not call this a true refractory mortar just because of adding sodium silicate. Portland and Lime are resistant to heat to a point, but are not refractory materials. What you have there is heat resistant mortar, not true refractory.

That said, it will last a long, long time.

[Campmaki]

Re: Cementing the bricks question

Stonecutter, I stand corrected. Anyways my vent is completed, now to start closing the whole build in. Thanks for your help along the way, Wayne