Refractory mortar setting

[Diswal]

Hi,

I am building an oven in Denmark and have acquired some refractory mortar which I am starting to use.

It is dry powder just to be mixed with water) but after curing the joints are still not very tough. If I use my nail I can scratch the joints. Also I forgot to cover it up one day when it was raining and the mortar became soft again but after drying up it became like before.

Does this sound odd or is this a normal property of the mortar?

I have attached the data sheet if it helps.

Thank you for your input.

[UtahBeehiver]

Re: Refractory mortar setting

It may be a heatset mortar so it won't harden until it is exposed to a specific temperature. Someone like Tscar will know better. Is there a brand name associated with the mortar then you can go online and find out more.

[texman]

Re: Refractory mortar setting

it looks like a similar product to what i used. It gains full strength at 800 deg F and up. And, the mortar only need to hold the brick in place, the strength is really in the dome shape.
Texman

[Diswal]

Re: Refractory mortar setting

Thank you very much for your replies, they have been very reassuring :-)

I have now also spoken with the producer and they also told me that the mortar will not become hard and set fully until the oven has been running for at least 4-5 hours.

Thanks again - this Forum has been a great help in all my planning :-)

/Joergen