抄録
Hydrothermal reaction was investigated for a recycling technology of sludge from water purification plant. The calcined sludge at 600 degree C for the removal of organic compound was mixed with Ca(OH)2 so that the Ca/Al atomic ratio was in the range from 0.08 to 1.09. Specimens were formed by uniaxial pressing at 30 MPa and hydrothermal treatment under saturated steam pressure between 160 and 220 degree C for 6 to 10 h. The Ca/Al ratio of the mixture had influence on the strength development. Hydrothermal reaction at 220 degree C for 10 h with Ca/Al = 0.29 yielded the maximum flexural strength of 13 MPa with a bulk density of 1090 kg/m3, resulting from the formation of about 100nm size hydrate. The high specific surface area (157m2/g) of the sample suggests an application as a humidity conditioning material.
