Sintered material from alkaline basaltic tuffs

The possibility to obtain sintered material from alkaline basaltic tuffs is demonstrated. The parent rock was milled for 10–15 min, the resulting powder was pressed at 100 MPa and the obtained samples were heat-treated in the range of 1000–1140 °C. The sintering behaviour and the phase formation were studied by pycnometry, dilatometry, DTA, XRD and SEM.The final material was obtained by sintering at 1100 °C and is characterized by zero water absorption, 8–9 vol.% closed porosity and a structure similar to a glass-ceramic. Due to high crystallization trend of used composition, phase formation takes place during the sintering and cooling steps; this leads to a crystallinity of ∼60% and formation of different crystal phases (pyroxene, anorthite, spinel and hematite).Despite the low-cost production cycle the obtained material is characterized by high mechanical properties: bending strength of 100 MPa and Young modulus of 90 GPa.