Forum / Refractory Mortar Questions :)

Michaeltcking

I've got a couple questions about selecting my refractory mortar. Any help would be appreciated :)

1) Is it important to match the composition of the mortar to the brick  (i.e. aluminum oxide, silica percentages)?

2) What is the minimum modulus of rupture recommended? I have access to 155 lbs/ft3 and 87 lbs/ft3

-Michael