Particles size and distribution on the improvement of the mechanical performance of high strength solid solution based inorganic polymer composites: A microstructural approach

This research reports on the influence of particle size and distribution on the physical, mechanical and microstructural features of solid solutions (feldspathic materials) based inorganic polymer composites (IPCs). Both granite and pegmatite were ground to different degree of finess making four different granulometry with particles of 63, 80, 125 and 200 μm. The respective mixes receive 15 wt% of metakaolin and were activated with a well designed alkaline solution. Matrices obtained showed high compressive and flexural strengths in the range 101.2–131.3 MPa, and 29–35.5 MPa, respectively. It was observed that the optimum mechanical performance of these matrices can be achieved through a mix-design of different grades of granulometry. This was suggested by mechanism combining reactivity and particles packing. In fact, although it can be expected that the finess of the combination of the particles size under 63 μm might present the better reactivity, it is showing that the combination of fine, medium and coarse particles is efficient in achieving denser and tougher microstructure. Lower cumulative pore volume (17 mL g⁻¹) of the composites based on pegmatite, value not far from that of natural stones, resulted in a higher impact resistance of 3.03 J. It was concluded that designing the feldspathic rock-based composites with high strengths appear as sustainable, low energy consumption and environmentally-friendly materials for the structural construction.