Foamed mortar is a building material with many air voids. It is produc
ed with the aid of a static mixer from a ready prepared foam and a fre
e-flowing mortar. During the mixing process large pieces of foam cover
ed in cement paste are split off and retain the foamed mortar structur
e with air void sizes x(p) less-than-or-equal-to 1.0 mm. The volumetri
c ratio of foam and mortar, expressed by the mortar fraction, has a de
cisive effect on the compressive strength of the foamed mortar. The ma
thematical relationship between the mortar fraction psiM and the foame
d mortar compressive strength beta(SM) can be described approximately
by a power function of the general form beta(SM) = a . psiM(b). This m
eans that the drop in compressive strength is disproportionately large
when the mortar fraction is reduced and that, for example, a foamed m
ortar with a mortar fraction psiM = 0.5 can only reach a maximum compr
essive strength of approximately 5% of the mortar compressive strength
. The water/cement ratio, the maximum particle size and the particle s
ize distribution of the aggregates, the foam concentrate, the foam sol
ution concentration and the foam density also have an effect in additi
on to the mortar fraction.