Metal powders as foaming agents in fly ash based geopolymer synthesis and their impact on the structure depending on the Na /Al ratio

Using metal powders, like Al-powder and Zn-powder, as foaming agents in geopolymer synthesis to produce lightweight, cement like building materials, is described in the following article. The influence of the porosity on the structure of the hardened paste is analyzed. Moreover, the influences of the ratio's variations of Na/Al in between 0.4 and 0.8 are investigated. Therefore, analytical methods, including X-ray diffraction, IR spectroscopy for structure analysis, SEM and optical microscopy for morphological analysis and mercury intrusion porosimetry for porosity analysis are used to characterize the synthesized geopolymers. We show the influences of different foaming methods on the geopolymer reaction. Moreover, the differences in element distribution of foamed and not foamed samples are investigated.