Utilize nano-scale metrology techniques to investigate mechanical, structural, and chemical heterogeneity of mixtures contained incineration bottom ash aggregate

The utilization of municipal solid waste (MSW) incineration bottom ash (IBA) in the infrastructure construction is a double-win solution to feed the fueling demand for building stones and binding materials. However, MSWIBA is a so highly heterogeneous and variable material that the macro-scale researched results cannot guarantee its behavior at any moment and under any conditions. Therefore, we should figure out why the heterogeneity will happen and how the heterogeneity affects the mechanical behavior of the mixtures. In this paper, the heterogeneity of mixtures contained IBA was investigated at nano-scale from the point of view of chemistry, microstructure, and micromechanics. Nanoindentation (NI) testing together with the image processing technique and statistical method was performed to evaluate the elastic modulus and creep parameters' variation in the measured regions. The test sample was then studied by FESEM observation to illustrate its disordered microstructure. Finally, elemental and phase investigation of the NI sample was carried out by Energy-dispersive X-ray (EDX), which further gave the fundamental arguments why the MSW IBA mixtures present apparent heterogeneous behavior. It can be concluded that nanoindentation elastic/creep testing, FESEM observation, and EDX chemical analysis give mutual verification to illustrate the heterogeneous phenomenon in IBA cement mixtures.