Refractory Mortar Question

[Balty Knowles]

Picked up my Refmix, hard to justfy the cost until you start using it. This stuff is awsome, Spreads like cream cheese, stays open right to the end & sets like a rock. Suggest mixing in small batches unless you know what you're doing. This rookie was able to handle 1/2 bag at a time, approx 12 halfbricks. My only other frame of reference is the high heat formula in the plans, which is very difficult to use, I ripped this out & replaced it with Refmix.

[james]

Balty,

Your floor and first course look great. Now on to the mortar; we want them to stay there for a long time. Can you give us more details on the al silicate that you used?

Every mortar has to have a setting agent, which is the product that forms a chemical reaction with the aggregate and water to set the final product. You can use Portland cement or Calcium Aluminate (sometimes called the trade name lumite). Without one of these, your mortar won't set.

Is it possible that your cal silicate was not Calcium Aluminate?
James

[james]

Wow. Talk about two ships passing in the night. I think the two previous postings were made at just about the same time.

Glad the Refmix works!
James

[redbricknick]

Not sure.. I haven't used al silicate. I use the same formula, but with portland cement in place of the alumina.. Works a treat. I add a little more fireclay to the mix than is prescribed, as it makes the mortar stickier and easier to work with.. Still has nothing on refmix for strength though.. I have some refmix which i have set aside for casting my vent.. Is the name refmix set? How do people feel about it. Any suggestions? Hows about, Fuegofrax, of flament, or refractoment, or cemax, refracto, or... FORNOFRAX?

[Balty Knowles]

I already ripped the 1st layer out & replaced it with Refmix but just as a reference for others. It was still wet after a week, I let a chunk dry overnight & I was able to pulverize it between my fingers the next day.

Attached is a picture of the bag. Aluminum Silicate, or Luminite. Notice the rocks in the scoop beside the bag. These were sifted out of 1/2 a scoop. Is this normal or could it have gone off in the brickyard. (Old Inventory maybe)

My formula was 3 dry #2 sand, 1 Calcium Aluminate (I sifted the rocks out), 1 Fire Clay (I think, see pic of bag), 1 Lime. It was measured accurately & dry mixed first.

I think the problem was that I wet sanded the floor using too much water before the mortar had cured.

[Balty Knowles]

last night I made 2 slugs of high temp mortar & stuck a couple of off cuts together so I could test the strength. After curing for 24 hours I was able to crush the mortar back to powder in my hands.

This eliminates my thought of over wetting the mortar when I sanded the floor last week & suggests that one of the ingredients is no good. I'm guessing its the Calcium Aluminate.

Any suggestions, are my ingredients wrong? Otherwise I should I go back to the store to let them know, I'd hate for some poor schmuck to finish an entire project before finding failure.

Regards

Balty

[Balty Knowles]

I called the technical manager at Caluchem today, they manufacture Lumnite. He told me my formula is way too light on the Lumnite he suggested the following mix for my oven mortar

2 parts sand
2 parts Lumnite (Aluminum Silicate)
1 part Fireclay

Omit the lime altogether, says it has no place in a refractory mortar.

The lumps in the Aluminum Silicate are very bad, I need to go back to the brickyard & inform him of the problem.

I will test this formula this weekend & let you know the results.

Rgds

Balty

[cristaldi]

Ok, after reading this thread I am confused. Are you all talking about two different mediums for construction?

One 'make yourself' and Two 'use Refmix'???

TIA

[asudavew]

Yes you can buy premixed high temp mortar.

Here's a link

http://www.fornobravo.com/store/RefMix-p-16154.html

Or you can make your own.
Using:

1 part cement
1 part lime
1 part fire clay
and
3 parts sand

There is also another recipe to make your own. It is supposed to handle higher temps and closely resemble refractory mortar


1 part calcium aluminate
1 part lime
1 part fire clay
and
3 parts sand

[Unofornaio]

Fire Clay does not reach its strength untill FIRED.