Emergency/Temporary chimney outside

So hey again everyone, it's just a newbie in Ohio.  I have now gotten my mass "couch" built, the heat riser has dried and I'm finishing up the water glass treatment to be ready to install this evening.  If I can ask just one tiny question?

As with so many places in the country right now, it's bloody cold and windy outside.  My layout has the exhaust going through an outside wall and then going up alongside the house.  When its warm enough for things to dry and cure, I plan to do a poured in place chimney of aircrete that will then have some decorative finish on it (rocks most likely).  In the meantime, I think I've come up with a way to insulate the outside pipe against the cold and wind with materials I have and can disassemble later?  What do you think?

also, I haven't gotten the pipe out of the heat riser yet.  My thinking being let it be structural while I treat the outsides first?  I pretreated it with vegi oil spray and was able to move it after the first pour to reposition it.  I'm hoping it comes out fairly easily when I pour boiling water down it but I'm hesitant as that inner tunnel will not have been stabilized yet with waterglass so the aircrete may get crumbly...  Any alternate ideas to avoid this would be welcomed.  These are the last pieces of my puzzle!

Jen

A cheap way to make an insulated chimney for a rocket mass heater is to use two ducts, say 6" and 8", and pack the space between with fiberglass. This will keep the chimney from cooling the draft too fast, and can be taken apart for other use later. I have had a 5' section of this at the top of my chimney for a few years now and it is still fine. You would want to make a sheetmetal cap for the top to keep rain from getting in, and have the laps between sections arranged to shed water to the exterior of the cavity so any water that got in would be able to drain out.

Obviously this would not pass code, but if it is temporary or you otherwise don't need to worry about that, it is a practical solution.