Utilization of circulating fluidized bed fly ash in preparing non-autoclaved aerated concrete production

Circulating fluidized bed combustion (CFBC) fly ash (CFA) is an industrial waste from CFBC boiler of electric power plant, which is not a good supplementary cementitious material for Portland cement and concrete because its expansive feature results in unexpected deterioration of concrete in the last stage. The non-autoclaved aerated concrete (NAAC) was developed using the CFA as main raw materials in this study. To find out the effect of raw materials on the products properties, rheological property of fresh pastes, physical, chemical, mechanical and microstructure analyses were performed. The results show the reasonable dosage of CFA, cement, and lime were 65.5%, 22%, and 10%, respectively. Medium diameter of CFA particle size ranges from 9.6 μm to 23.9 μm is the most suitable for preparation of NAAC duo to the matching condition between thickening rate of the slurry and the reaction rate of aluminum powder and water. The principal minerals in NAAC are needlelike AFt and floccular C–S–H, be different from autoclaved aerated concrete (AAC).