Properties of sintered low calcium bottom ash aggregate with clay binders

This paper focuses on the properties of sintered aggregates with low calcium bottom ash from coal fired thermal power plants using a wide range of clay binders through pelletization process. The experimental runs were designed using central composite design of response surface methodology. The aggregate was produced using a disc pelletizer. The pelletized aggregate was sintered at 800–1100 °C for 30–120 min. Sintered aggregates were tested for bulk density, 10% fines value and water absorption. The factors involved in the process are moisture content, binder, Ca(OH)2 dosage, sintering temperature and duration. It was observed that an increase in binder dosage and sintering temperature resulted in aggregates with higher 10% fines value and low water absorption. The properties of aggregates depended on the type of binder used. Aggregate with kaolinite and metakaolin binders resulted in high 10% fines value. The results indicate the potential for manufacturing high quality lightweight aggregate from bottom ash using clay binders.

Research highlights
► This paper focuses on the properties of sintered aggregates with coal bottom ash.
► Wide range of clay binders were used to improve the properties of these aggregates.
► Increase in binder dosage and sintering temperature enhanced the properties of the aggregates.
► Aggregate with kaolinite and metakaolin binders resulted in high 10% fines value.
► The properties of aggregates depended on the type of binder used.