Characteristics of Porous Ceramics Produced from Waste Diatomite and Water Purification Sludge

In this investigation, samples of waste diatomite and water purification sludge were subjected to a constant pressure of 5 MPa, sintering temperatures of 1000°C to 1270°C, and a sintering time of 2 hours to determine the suitability of the materials for the development of porous ceramic products. The percentage of water purification sludge mixed in the waste diatomite ranged from 0% to 20%. Under the operating conditions just described, a homogeneous melt with a viscosity that allowed the samples to be shaped was obtained. Microstructures, crystal structures, and volumes of the pores of the ceramic samples were then determined by X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry, respectively. When the heating temperature was 1270°C, porous ceramic samples of diatomite containing 20% water purification sludge had a density of 0.97 g/cm3, a porosity of 49.9%, a water absorption of 51%, a shrinkage of 15.3%, and a high compressive strength (18.3 MPa). When heated to this temperature, sintered samples contained pores of approximately 2.5 μm to 3 μm, and they yielded a small peak in around 0.3μm to 2 μm. In summary, porous ceramics samples of 80% diatomite and 20% water purification sludge have favorable mechanical properties and therefore may be utilized in several applications, particularly as a water-retaining material in pavements.