Effect of biological and agricultural foaming agents on concrete waste for the preparation of porous ceramic materials

Abstract This study offers a novel method for recycling leftover concrete to create porous ceramic materials. Various pouring agents, such as starch mixed with flour, yeast, baking powder, wheat straw, or sawdust, have created porous waste concrete ceramic materials. The starch is a binder for ceramic particles and a growth substrate for forming gas bubbles. Utilizing starch consolidation procedures, the green bodies are produced by firing them at temperatures of 1200 °C, 1250 °C, and 1300 °C. Various techniques characterize the fired sample, including Fourier Transform Infrared Spectroscopy, Thermogravimetric analysis, Differential Scanning Calorimetry, Apparent porosity, Bulk density, Compressive strength, Phase composition, and Microstructure. The acquired results showed that apparent porosity decreased except for samples containing baking powders, while the bulk density and compressive strength increased as the firing temperature increased. With apparent porosity of 56% and 39%, bulk density of 1.27 g/cm 3 and 1.64 g/cm 3 , and mechanical characteristics of 0.55 MPa and 1.47 MPa at 1250 °C and 1300 °C, respectively, samples containing flour have a highly porous structure. At 1250 °C, the thermal transmittance of this sample reaches 0.327 W/m 2 K. The sawdust-containing sample exhibited the highest strength, reaching 1.54 MPa at 1250 °C and 5.23 MPa at 1300 °C. At those respective temperatures, its apparent porosity measured approximately 55% and 38%. Additionally, sawdust samples had a thermal transmittance of up to 0.336 W/m 2 K. Therefore, the current study created porous structure ceramics by substituting all or some of the more expensive polymer additives with recycled concrete debris. The resulting ceramics are potentially used in gas burners, membranes, filters, and refractory thermal conductivity.