Microwave Materials Characterization of Geopolymer Precursor Powders

Geopolymers are structural materials that can be used as a viable alternative to ordinary portland cement concrete. However, their widespread adoption has been limited by the lack of understanding in their fundamental reaction mechanisms. Microwave characterization methods have shown promise at understanding these reaction mechanisms. However, the complex dielectric properties of geopolymer precursor powders and the effect of void content must first be understood. Therefore, in this work, the dielectric properties of two geopolymer precursor powders (blast furnace slag and fly ash) are measured. Then, the effect of void content and particle size distribution (PSD) is considered on the measured dielectric properties. By characterizing the inherent void content of these powder materials, this effect can be removed and therefore the true dielectric properties of the materials can be determined. The results show that the void content has a significant effect on the measured dielectric properties.