Pinheads,

    Having recently done a project in Denmark, I have had an encounter with a
product that would earn the nickname "popcorn" concrete.  The Danes use a
variety of cinder block which uses a very light aggregate that resembles
volcanic pumice.  The blocks are very large and light and seem to offer
little in the way of structural integrity.  They can be shattered with a
small sledge or a good whack with a piece of dimensional lumber.  They do,
however, provide relatively high r-values for masonry.  They were used for a
starter course on my project to support walls made of clay slurry and wood
chips.  They had the additional benefit of providing a moisture barrier and
venting for the wall system.

David J. Dauerty

To The Line Timber Frames