Thermal, mechanical, and microstructural properties of inorganic polymer composites from quarry wastes (feldspathic minerals)

In the recent century, geopolymer materials have grown significantly due to their unique properties applicable in many different fields. In the present work, the heat evolution, thermal and mechanical behavior of inorganic geopolymer composites (IPCs), based on solid solution of feldspathic minerals (pegmatite and granite) or sand quartz that were altered by a low fraction (15–20 mass%) of calcined clay (metakaolin or calcined halloysite). The isothermal calorimeter tests revealed that the heat flow evolution (dQ/dt) of mix design of different compositions was low compared to standard geopolymer materials due to low reactivity in alkaline medium of solid solution used. It was also found that the integrated heat flow during the geopolymerization decreases with the crystallinity of solid solution. The thermogravimetric analysis of all the samples revealed two main changes, before 120 °C and between 700 and 890 °C. The changes are attributed to the loss of water molecules and crystallization of albite and nepheline, respectively with an overall loss of mass which varies from 14.0 to 21.6%. The heating microscope up to 1200 °C shows a shrinkage of 50% for D3C4 and R2C1 samples. The study of mechanical and physical behaviors of geopolymer composites with different compositions showed that samples based on pegmatite and MK developed higher strengths (42.11 MPa and 106.75 MPa for flexural and compression) associated with lower water absorption (7.01%). The high strengths obtained were due to the combination of denser and homogeneous microstructure of IPCs. These materials are potential candidates for eco-friendly construction materials.