Conductivity/efficiency of red clay brick

I’m looking into Matt walkers j-tube design, of which the mass is primarily brick.

My question is how well/ does brick perform in contrast to cob, in terms Effie irntly storeing the heat or any other criteria for that matter.

Hey Wes,

Cob, as well as any uncooked earth, is not as good of a thermal mass as fired brick. Un-fired earth breathes more--which has its own applications... Additionally, an industrial-made brick is VERY dense, and that also means better thermal mass.

https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

https://www.engineeringtoolbox.com/sensible-heat-storage-d_1217.html

Satamax Antone wrote:https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

https://www.engineeringtoolbox.com/sensible-heat-storage-d_1217.html

Those are some pretty cool charts. Too bad the sensible heat storage chart doesn't include anything of natural earth...

Nathanael Szobody wrote:

Satamax Antone wrote:https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

https://www.engineeringtoolbox.com/sensible-heat-storage-d_1217.html

Those are some pretty cool charts. Too bad the sensible heat storage chart doesn't include anything of natural earth...

Well, i just did a quick search to lead you guys there. I'm pretty sure there is an extended chart. Somewhere. You will have to dig it yourselves.

That was a revealing chart.

It would seem that brick is the way to go, rather than Cob, except for cost.

If one merely stacked the bricks with out mortar would it substantially diminish the thermal storage of the mass?

Wes, the air gap that it makes between bricks, slows the travel of the heat through the joints. Better to glue your bricks up with mud. Just sieve some dirt, and use that.

When you say save some mud, do you mean to use cob material in lieu of mortar?, is mud/cob mortar easier to break apart than traditional mortar?

Sieve some mud, yep. Not even clay.  Just mud without rocks. If you need to reuse your bricks, just scrape znd wet them.  

Hi Wes;

Yes, mortar is harder than the clay brick it is on . Very common for the brick to break before you can remove the mortar. As Max said,  Cob/ mud will pop right apart and scrape clean in seconds.