Abstract
Incinerator Bottom Ash Aggregate (IBAA), produced as a by-product from Energy-from-Waste (EfW) facilities in Scotland, is gaining acceptance as a sustainable alternative for concrete applications. This shift is driven by Scotland’s forthcoming landfill ban, which encourages increased recycling and diversion of waste from landfill. This study presents a detailed characterization of IBAA, sourced from four Scottish incinerators across various particle size fractions. Physical testing showed that the coarse IBAA fractions (12–22 mm) meet BS EN 8500-2 for use in ready-mixed and precast non-structural concrete. Furthermore, Los Angeles abrasion values (36–42%) and flakiness indices (13–18%) lend themselves well to this type of application. Constituent analyses confirmed compliance with limits for unbound aggregates, brick, glass, and other materials, supporting their suitability in concrete. Chemical analyses revealed that acid-soluble sulfate content in coarse fractions remained around 1%, well within acceptable limits, while finer fractions displayed higher sulfate levels. Metal analysis showed aluminium contents below 1%, with total ferrous and non-ferrous metals typically ranging from 1–2%. X-ray diffraction indicated a predominance of non-crystalline (amorphous) material, as well as beneficial crystalline phases such as calcite, quartz and gehlenite, especially in coarser fractions. Overall, the study demonstrates that the four IBAAs, particularly their coarse fractions, are good-quality, sustainable materials suitable for replacing natural aggregate in non-structural concrete. The use of IBAA can contribute to circular economy goals by reducing landfill use and conserving natural resources.
Keywords
recycled aggregate, sustainability, circular economy, IBAA, incinerator bottom ash aggregate, Scotland.
DOI
10.5703/1288284318107
Recommended Citation
Norouzifar, Mohammad Naser; Dyer, Tom; and Newlands, Moray, "Characterization of Incinerator Bottom Ash Aggregate (IBAA) from Four Scottish Incinerators" (2025). International Conference on Durability of Concrete Structures. 8.
https://docs.lib.purdue.edu/icdcs/2025/sce/8
Characterization of Incinerator Bottom Ash Aggregate (IBAA) from Four Scottish Incinerators
Incinerator Bottom Ash Aggregate (IBAA), produced as a by-product from Energy-from-Waste (EfW) facilities in Scotland, is gaining acceptance as a sustainable alternative for concrete applications. This shift is driven by Scotland’s forthcoming landfill ban, which encourages increased recycling and diversion of waste from landfill. This study presents a detailed characterization of IBAA, sourced from four Scottish incinerators across various particle size fractions. Physical testing showed that the coarse IBAA fractions (12–22 mm) meet BS EN 8500-2 for use in ready-mixed and precast non-structural concrete. Furthermore, Los Angeles abrasion values (36–42%) and flakiness indices (13–18%) lend themselves well to this type of application. Constituent analyses confirmed compliance with limits for unbound aggregates, brick, glass, and other materials, supporting their suitability in concrete. Chemical analyses revealed that acid-soluble sulfate content in coarse fractions remained around 1%, well within acceptable limits, while finer fractions displayed higher sulfate levels. Metal analysis showed aluminium contents below 1%, with total ferrous and non-ferrous metals typically ranging from 1–2%. X-ray diffraction indicated a predominance of non-crystalline (amorphous) material, as well as beneficial crystalline phases such as calcite, quartz and gehlenite, especially in coarser fractions. Overall, the study demonstrates that the four IBAAs, particularly their coarse fractions, are good-quality, sustainable materials suitable for replacing natural aggregate in non-structural concrete. The use of IBAA can contribute to circular economy goals by reducing landfill use and conserving natural resources.
