A field-scale evaluation of municipal solid waste incineration bottom ash as a road base material: Considerations for reuse practices

Abstract

Laboratory studies indicate that municipal solid waste incineration (MSWI) bottom ash (BA) can serve as a suitable road base material. However, very little is known about how field-scale design variables, such as layer thickness and compaction effort, and changes in moisture content over time affect the long-term performance of MSWI BA base courses. Understanding how these parameters affect the physical performance of BA base courses is necessary for developing construction specifications and guidelines specific to this material – a critical step in promoting widespread reuse practices. In this study, processed MSWI BA aggregate was tested in a field-scale test facility that replicated real-world scenarios to examine their effects on two important material properties: resilient modulus and permanent deformation. These results suggest that layer thickness, compaction effort, and moisture content can affect the base layer's resilient modulus and the permanent deformation, with moisture content having the most significant impact. Moisture content above the material's optimum decreased base modulus and increased permanent deformation, but the degree of deformation proportionally decreased with increasing layer thickness. Based on these results, guidelines on designing and reusing MSWI BA as a base course are discussed, suggesting optimal performance from highly compacted, thicker layers while stressing a need for tight control of moisture during and post-construction.