Study on the environmental resistance of foamed lightweight soil material from sintered dust
In order to realize the resource utilization of industrial solid waste dust-based foamed lightweight soil in transportation infrastructure construction,this paper puts forward the performance improvement technology of dust-based foamed lightweight soil and develops a new material of dust-based foamed lightweight soil to evaluate the mechanical properties,water stability and durability of dust-based foamed lightweight soil under different mix ratios after composite modification.The microstructure changes and strength formation mechanism of the material is also explored before and after modification.The results show that the nonionic surfactant(AEO-9)can significantly improve the foam stability and the wettability of the dust,and the optimal dosage is 20％of the mass of the original foaming liquid and 0.4％of the mass of the dust,respectively.After composite modification,the content of dust ash is up to 50％,the 28 d strength of dust ash-based foam lightweight soil reaches 2.08 MPa.The water absorption and softening coefficient are 21.4％and 0.765 respectively.The strength losses of dry-wet cycle and freeze-thaw cycle are 13.8％and 17.3％,respectively,which meets the requirements of water stability and durability index.The results of scanning electron microscopy show that the microscopic pore structure of the composite modified fly ash-based foamed lightweight soil is significantly optimized,and the proportion of bubbles with a diameter of less than 200 u m increases from 32.54％to 52.2％.The results of XRD analysis further show that the slag powder is helpful to improve the initial strength of the material in the alkaline environment,and the Fe2O3 in the dust is helpful to form a stable hydrated tricalcium aluminosilicate C3(AF)H6 after the activation of the activity,which further improves the strength of the material.The dust-based foam lightweight soil modification method and its new materials provide a cost-reduction and efficient way for the resource utilization of industrial solid waste in the backfilling engineering.
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