Influence of microstructural and morphological properties of raw natural clays on the reactivity of clay brick wastes in a cementitious blend matrix

Abstract The physical, chemical, and mineralogical characteristics of raw clays used in the industries interfere greatly in the production process and final ceramic product. Raw clays from 4 industries in the South of Brazil were characterized by the XRD, XRF, FTIR, DSC, and SEM techniques. In addition, the pozzolanic potential was also verified based on the kaolinite content of the raw samples. The raw clay that presented the highest pozzolanic potential had a quantity of kaolinite of 69.7%. The use of 40% of the brick waste produced with this raw clay (particle size of 75 μm) replacing Portland cement in a mortar resulted in a gain of 51% in compressive strength at 28 days. The analysis of the hydration products resulting from the Ca(OH)2 reaction from the cement hydration with the ceramic waste showed the presence of Al2O3.2SiO2 forming the C-S-H gel.