Using different types of mortar

[Jayson]

Hi all,

Let me start by saying how much I have appreciated all of the information I have read on the Forno Bravo forum, which has led me to begin building my own Pompeii oven. The build is going well and is up to the second row.

Question 1
I have a question about mortar. I am using a castable refractory product which comes dry, I just add water and hey presto a fantastic mortar! This stuff is super strong and has bonded really well with the firebricks. It is easy to work with and goes off reasonably quickly to allow me to move on with the build. My question is, can I use another type of mortar to fill in the small gaps? The castable refractory has small aggregate in it which is approximately 3mm in size. Not great for the tiny corners where the brick faces meet. I am considering sifting out the aggregate and using the finer mix. Kind of like a grout, and use this mix to point up small gaps. I'd love to know everyones thoughts on this.

Question 2
Also I have large gaps at the back of the bricks that will need to be backfilled. Castable refractory mix is going to get expensive if I fill all of the big gaps with this. Can I use a cheaper/home made mortar to fill up the gaps at the back?

My refractory supplier sells Cement Fondue which can be mixed with sand. Would this be a good solution to both my problems, it is cheaper and only seems to have sand as the aggregate (unless I am mistaken)

Anyway, I've searched high and low on the forum but not found anyone that has mixed mortar types. I am keen to know what the best way forward should be?

Thanks in advance

[nissanneill]

Re: Using different types of mortar

Hi Jayson and welcome aboard.
Great to see another Aussie on deck.

I have large gaps at the back of the bricks that will need to be backfilled. Castable refractory mix is going to get expensive if I fill all of the big gaps with this. Can I use a cheaper/home made mortar to fill up the gaps at the back?

I built my Pompeii with only the poor man's mortar with absolutely no cracks nor problems. i would not use the refractory products for several reasons as many other members who have used it are reporting cracks and other problems, let alone the extra cost.
I would certainly use it to fill the back voids but not to add extra thermal mass.

Cheers.

Neill

[david s]

Re: Using different types of mortar

Jayson, the castable refractory is designed to be used to cast pieces rather than used as a mortar. Your supplier should bee able to supply a calcium aluminate cement mortar which is designed as a mortar. Sifting out the course aggregate will end up giving you a richer mixture than you require and will be quite expensive. I think you are better to use the poor mans mortar. It works really well, is easier to apply, has a longer pot life and is way cheaper.

[Jayson]

Re: Using different types of mortar

Thanks Neill, I appreciate the insight. I have been pretty happy with the castable as the mortar but appreciate your knowledge. I have not seen any cracking as yet, it seems really stable and quit adhesive. I did notice that if the bricks werent wet the mixture dried super quick and wnet crumbly. Cleaned it off and started again ensuring all bricks were wet and it went really well.

Thanks David, for you help too. I noticed from your profile that you have built quite a few ovens. I hope they are still standing and all is well up your way since cyclone Yasi. Take care.

[david s]

Re: Using different types of mortar

Thanks Jayson, yes we're all ok up here. The only casualty was a fella who asphyxiated himself from using a generator indoors.There are tons of trees down here and the council has estimated there are 7 million cubic metres of green waste on peoples footpaths to pick up. It will take months.

[Jayson]

Re: Using different types of mortar

Hi David, we heard about the young guy with the generator in his house, the cyclone has been big news down south and we've been following it. All the very best of luck.

[Jayson]

Re: Using different types of mortar

I have just added a web albumn in Picasa
https://picasaweb.google.com/1140387...eat=directlink

I have also added a FB albumn.

[OscarA]

Re: Using different types of mortar

Hi Jayson just checked your album and those brick cuts are very impressive.
I'll be following this thread with great interest.
I'm also in Melbourne so it's good to see another Melbournian building an oven.
I'm at the stand stage so a few steps behind you.

[Jayson]

Re: Using different types of mortar

Thanks Oscar. I checked out your stand and it looks great, well done.