"The new method of using cast-in-place foamed concrete with stay-in-place forms... offers several advantages. ...[It] can be adapted to a variety of requirements, and the new construction system... [a]llows hollow spaces to be blocked out in the walls for the installation of utilities or for steel-reinforced concrete pilasters that are integral with the wall."
January 1, 1970
https://en.wikiquote.org/wiki/Foam_concrete