Experimental study on the influence of curing conditions on the mechanical performance of municipal solid waste incinerated-bottom ash (MSWI-BA)

In this study, three groups of municipal solid waste incinerated-bottom ash (MSWI-BA) with different particle sizes (1.18–2.36 mm; 2.36–4.75 mm; 4.75–9.5 mm) were separately treated under natural dry, half-wet, and wet condition, to investigate the possibility of their mechanical performance. The strength of MSWI-BA was periodicity tested by crushing value test. The changes of microstructure and mineral components over curing time were separately analyzed via scanning electron microscopy-energy dispersive spectroscopy (SEM–EDS) and X-ray diffraction (XRD). The results show that the MSWI-BA requires long curing time to develop a certain strength, and the highest strength of MSWI-BA is obtained under half-wet curing condition. The strength development of MSWI-BA is attributed to the formation of hydration products of calcium silicate hydrate (C-S–H) and the increase in well-crystallized minerals of CaCO3. In addition, the results of the indoor long-term immersion test show that the heavy metal leached concentrations of MSWI-BA are far below the limited values in China standard GB 5085. In addition, the curing can solidify heavy metals to a certain extent, ensuring the safety of MSWI-BA as a road construction material.