STRUCTURE AND STRENGTH OF CEMENT-BOUND FO AMED MORTAR

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.