Preparation and characterization of a composite material based on a geopolymer binder and quartzite aggregates

We have developed a geopolymer material by alkaline reaction on thermally activated kaolin. Initially we characterized the geopolymer by different methods (rheology, DTA-TGA, etc.) and we mixed it with different amounts of natural sand to obtain a granular composite. The structural characterization of this material was undertaken by several techniques (XRF, XRD and microscopic observations). A rheological study was implemented to determine the influence of the aggregate rate on the setting kinetic. Three-point bending and compression tests were conducted for mechanical characterization. We also conducted microindentation tests to study the influence of quartzite rate on the hardness of the material. The results indicate that the integration of quartzite (up to 15 wt. %) did not alter the setting kinetic. We noted a small degradation of the mechanical behavior when the quartzite rate is increased; this effect is due to a higher density of microcracks. However, adding the aggregate has a beneficial effect on the hardness of the material. These attractive features make this material a plausible matrix whose reinforcement with plant fibers will provide a ternary composite suitable for multiple applications.