Effect of Different Types of Aluminosilicates on the Thermo-Mechanical Properties of Metakaolinite-Based Geopolymer Composites

In this study, the effect of different types of aluminosilicates on the thermo-mechanical properties of metakaolinite-based geopolymer binders and composites was examined. The metakaolinite-based geopolymer binders and composites were produced from three different types of aluminosilicates (one metakaolin and two calcined claystones) and a potassium alkaline activator. Chamotte was added as a filler, amounting to 65% by volume, to create geopolymer composites. Geopolymer binders were characterized by X-ray diffraction, rotary rheometer and scanning electron microscopy. The mechanical properties, thermal dilatation and thermal conductivity were investigated on geopolymer composites with three different aluminosilicates before and after exposure to high temperatures (up to 1200 degrees C). The results showed that the geopolymer binders prepared from calcined claystones had a lower dynamic viscosity (787 and 588 mPa center dot s) compared to the geopolymer binders prepared from metakaolin (1090 mPa center dot s). Geopolymer composites based on metakaolin had lower shrinkage (0.6%) and higher refractoriness (1520 degrees C) than geopolymers from calcined claystones (0.9% and 1.5%, 1500 degrees C and 1470 degrees C). Geopolymers based on calcined kaolinitic claystones are a promising material with higher compressive (95.2 and 71.5 MPa) and flexural strength (12.4 and 10.7 MPa) compared to geopolymers based on metakaolin (compressive strength 57.7 MPa).