Yesterday I cut off strips of the vermiculite/cement mixture from the edges of the hearth to accomodate the steel track. I wanted to fix the track directly to the regular concrete as the vermicu-crete layer had crumbled along the edges through 3 months of construction.
Anyway, while the stuff was hard as a rock from above, my circular saw with masonry blade cut through it like butter. When I chiseled the strips off I was amazed at how light they were (my 9 year old got to impress his friends by carrying around a cinder block sized piece with one hand).
One thing that amazed me is that although the top inch and a half was dry and cured, the mix was still moist and crumbly inside! Again, this is 3 months later! I know that many have fixed their enclosures to this layer without difficulty, but I am glad I made the decision to go to the "real" concrete.
Anyway, while the stuff was hard as a rock from above, my circular saw with masonry blade cut through it like butter. When I chiseled the strips off I was amazed at how light they were (my 9 year old got to impress his friends by carrying around a cinder block sized piece with one hand).
One thing that amazed me is that although the top inch and a half was dry and cured, the mix was still moist and crumbly inside! Again, this is 3 months later! I know that many have fixed their enclosures to this layer without difficulty, but I am glad I made the decision to go to the "real" concrete.