Tried a homemade refractory mix with portland cement and got a nasty crack on day two

I mixed up a batch of portland cement and sand for a little furnace liner repair, 3:1 ratio like some guy online said. It cracked right down the middle after firing once, so I learned the hard way that proper fireclay is worth the extra $12. Anyone else skip the fireclay and regret it?

2 comments

2 Comments

parker_patel841mo ago

I used to think fireclay was just overpriced dirt and that portland cement would work fine if you dried it slow enough. But yeah, I mixed up a batch for a small forge last year and watched it crumble after one heat cycle. That crack down the middle sounds exactly like what I got. Now I just pay for the proper stuff and sleep better.

andrew_nguyen641mo ago

Learned that lesson myself @parker_patel84, that crack always shows up right when you think you are safe.