"Over the past 30 years, FC are widely used for the bulk filling... ditch repair, retaining wall...bridge backfill... slab structure of concrete floor... and housing insulation... etc. ...Currently, people are increasingly interested in using it as a nonstructure or semistructure member for underground engineering, such as grouting works for tunnels, damage treatment, and liner structures."
January 1, 1970
https://en.wikiquote.org/wiki/Foam_concrete