An Attempt to Reduce Materials Cost of Autoclaved Aerated Concrete Production

Background: Municipal solid waste incineration (MSWI) bottom ash contains a not insignificant amount of metallic aluminum, while circulating fluidized bed combustion (CFBC) fly ash is rich in active SiO2. Objective: To reduce the materials cost of autoclaved aerated concrete (AAC) production, these two types of solid waste could theoretically be used as the aerating agent and silica source, respectively. Method: In the present work, the metallic aluminum concentration in an MSWI bottom ash sample was determined from hydrogen generation and this ash was used to make AAC in conjunction with CFBC fly ash. The extent of air entrainment in the resulting AAC specimens was varied by changing the bottom ash to fly ash ratio, and the effects of this ratio on the properties of the AAC were investigated. Results: Results showed that the ratio has a negligible effect on both the type and the morphology of the hydrates in the AAC, but is inversely proportional to the compressive strength, density and volume stability. Conclusion: This study proves that AAC having satisfactory properties can be successfully prepared from a combination of MSWI bottom ash and CFBC fly ash.