I know you are sick of reading it but I get somany different versions of mortar its good to toss things around.
Just spoke to a guy who says fireclay will not set if used in the tunnel mortar, it needs to go up to 1000degress to do that.
if you are in melbourne then here is his info
Refractory Installations Australia - more info »
3 Edinburgh St, Oakleigh South, VIC 3167 - (03) 9562 6843
I'm going to drop on in when we get closer to building the tunnel and have a chat (ring first he asked)
The thing about all this is the longer you wait to commit to a decision the more info you gather, then make whatever decision sits best with you and live with it.
At this moment i'm going with the 2 bags of refactory mortar at $45 a piece and save myself ALOT of hassles. He also wasn't worried when I told him i was using solids and not firebricks.
