Spark plasma sintering using siliceous waste concrete powder

Spark plasma sintering (SPS) was performed using siliceous waste concrete powder for the effective utilization of waste concrete. The sintering temperature of the SPS compacts was optimized to improve their mechanical properties. Siliceous waste concrete powder was prepared using a pot‐milling procedure of waste concrete. SPS was conducted by varying the sintering temperature from 1173 to 1273 K. Consequently, the Vickers hardness (HV), flexural modulus, and flexural strength were maximized at a sintering temperature of 1248 K. At a sintering temperature of 1248 K, the HV, flexural modulus, and flexural strength were 604, 66.3 GPa, and 75.0 MPa, respectively. Thus, the proposed SPS compact possessed twice the flexural strength defined in the ISO 13006 standard (35 MPa), which classifies ceramic tiles. Furthermore, diopside synthesis was detected owing to the decarburization of calcite during sintering. Therefore, siliceous waste concrete powder is a promising raw material for ceramics processed using SPS.