Fabrication of pure phase calcium carbonate hardened bodies as a means of creating novel geomimetic ceramics

To date, there have been few reports of the fabrication of hardened, pure calcium carbonate specimens beginning from the powder state. In this study, hardened calcium carbonate bodies exhibiting high densities and compressive strengths were produced using a warm press method. The warm press conditions consisted of temperatures from 150 to 280 °C and a uniaxial pressure of 240 MPa, applied for durations of 10-180 min to powder compacts composed of pure calcium carbonate powder or powder mixed with 10% water (by mass). Heating at 150 °C and 240 MPa for 180 min with 10% water generated a relative density of 87% and an average compressive strength of 40 MPa. The added water was found to play an important role to promote a solution-precipitation process inside the calcium powder compact, allowing low temperature sintering to form dense calcium carbonate.