Effects of Circulated Fluidized-Bed Fly Ash, Ground Granulated Blast-Furnace Slag and Coal Fly Ash on Properties of Mortars

Abstract

The amount of circulating fluidized bed combustion (CFBC) ash is increasing and the disposal cost of CFBC ash have also been increasing annually. Hence, developing a better utilization of CFBC fly ash with the by-products ground granulated blast furnace slag (GGBFS) and coal fly ash is an urgent and important task. In this study, seven mixes with different blended cements were prepared to cast mortar specimens. Flow test, setting times test, water absorption rate, compressive strength test and flexural strength test were performed to investigate the properties of mortars. Test results show that the addition of coal fly ash, CFBC fly ash, and GGBFS improves the workability.When the amount of cement replacement by CFBC fly ash, GGBFS, and coal fly ash was recommended less than 20% simultaneously, the compressive strength is higher than that of plain cement mortar. However, CFBC fly ash would results in a lower strength when adding up to 30%. Thus, the amount of CFBC fly ash replacement cement was recommended to be limited below 20% and the total amount of cement replacement was limited below 60%.