Effect of the Ca-to-Si ratio on the properties of autoclaved aerated concrete containing coal fly ash from circulating fluidized bed combustion boiler

The Ca-to-Si (C/S) ratio appropriate for autoclaved aerated concrete (AAC) containing fly ash from pulverized coal combustion (PCC) boiler may not be equally suitable for AAC containing fly ash from circulating fluidized bed combustion (CFBC) boiler. We investigated the effect of the C/S ratio on the properties of AAC containing CFBC fly ash, using AAC containing PCC fly ash as the control. Results showed that AAC containing CFBC fly ash and AAC containing PCC fly ash have distinct properties. Furthermore, the C/S ratio affects the properties of AAC containing coal fly ash by altering the hydrates and pore structure of the AAC. To achieve satisfactory mechanical properties, a higher C/S ratio should be adopted for AAC containing CFBC fly ash as compared with AAC containing PCC fly ash. We confirmed that the C/S ratio of AAC containing PCC fly ash should not be randomly applied to AAC containing CFBC fly ash, owing to the unique properties of CFBC fly ash.