MSW incineration bottom ash (MIBA) as a substitute to conventional materials in geotechnical applications: A characterization study from India and comparison with literature

Abstract

The study characterizes Delhi municipal solid waste incineration (MSWI) bottom ash (MIBA) collected from three incineration plants over a period of 1.5 years in different seasons (monsoon, winter, summer). Physicochemical characteristics such as chemical composition, visual composition, grain-size distribution, specific gravity and loss on ignition as well as geotechnical characteristics i.e., compaction behaviour, permeability, compressibility and shear strength were ascertained on soil-sized fraction of Delhi MIBA (SSF-DBA) and the material was assessed for suitability of geotechnical reuse. Furthermore, the results were compared with three locally available granular materials i.e., Badarpur sand, Yamuna sand and coal bottom ash. Present work is the first detailed characterization on MIBA from a lower-income nation which also attempts to evaluate the differences (or similarities) with MIBA from higher-income nations through a comprehensive compilation of global experimental data.The study reveals higher SiO2, lower CaO and lower Fe2O3 content of SSF-DBA in comparison to higher-income nations. Additionally, greater percentage of fines and lower compacted unit weight has been observed for Indian MIBA. While permeability and compression index of SSF-DBA are similar to the results reported from other countries, angle of shearing resistance lies in a narrow range of 40-46° in comparison to the wide range of values (24-59°) reported in literature. The influence of different seasons on properties of SSF-DBA was only attributable to MSWI plant’s combustion efficiency as more unburnt organics resulted in lower stiffness and reduced shearing resistance of SSF-DBA. Mechanical behaviour of SSF-DBA compares favourably with other granular materials.