"For a specified volume of foam, the PP fiber significantly improved the hardened strength. ...This advantage was also observed in the FC specimens with SF. Nevertheless... addition of PP fiber condensed the flowability of mix. Thus, we increased dosage... 0.8% fiber content was the best... level on the basis of a swap between performance enhancement and flowability loss."
January 1, 1970
https://en.wikiquote.org/wiki/Foam_concrete