Fired clay bio-bricks were prepared by adding eggshell as a bio-filler and flux into earthenware clay compounds via an extrusion process. In this study, the suiTab. conditions for clay bricks preparation were firing at 1000 o C for a period of 5 h. Adding 20 wt% eggshell powder into the clay brick yielded good physical-mechanical-thermal properties: high compressive strength and hardness, low thermal expansion coefficient, and low water absorption. The measured compressive strength, hardness, and refractory water absorption were 7.0 MPa, 6.0 HV, and less than 15 wt%, respectively. The obtained clay brick with the eggshell powder added as shown here is potential for uses as bricks for construction and thermal insulation.

Abstract. Eggshell functioned as a bio-filler and sintering aid added into earthenware clay compounds to make fire clay bricks via extrusion process. The main composition of eggshell is calcium carbonate (CaCO 3 ) while the main composition of earthenware is aluminosilcate (Al 2 O 3 .2SiO 2 .2H 2 O) and other oxide compounds. Calcium carbonate in eggshell can react to chemical substances in earthenware clay compound to form calcium alumnosilicate or anorthite and wollastonite or calcium silicate phase formation of the fired clay bricks. Adding 20%wt eggshell powder into clay bricks and fired at 1000°C for 5 hrs., affects to the physical-mechanical-thermal properties, i.e. high compressive strength and hardness, good thermal expansion coefficient, good true density, and low water absorption. In general, the theoretical compressive strength, hardness, and water absorption of desired refractory are more than 7.0 MPa, 6.0 HV, and less than 25%wt, respectively. Therefore, the obtained fired clay bricks added eggshell powder and fired at 1000°C for 5 hrs., are potential for use as bricks for construction and thermal insulation.