Novel hydraulically bound base course material from recovered munincipal solid waste incineration bottom ash (MSWI BA) and industrial by-products

In this study different fraction of recovered municipal solid waste incineration bottom ash (MSWI BA) was tested for a hydraulically bounded base course material. Portland cement is commonly used as a hydraulical binder in... [ view full abstract ]

In this study different fraction of recovered municipal solid waste incineration bottom ash (MSWI BA) was tested for a hydraulically bounded base course material. Portland cement is commonly used as a hydraulical binder in base course stabilization. An alternative hydraulic and pozzolanic materials e.g. biomass fly ash (BM-FA), coal fly ash (CFA) and lime have been tested as a partial substitute for cement for this purpose (Lynn et al. 2017). The purpose of this study was to test if industrial by-product based binder could be used for cement substitute. The potential of BM-FA, waste gypsum from phosphoric acid production process, waste burnt lime and milled 0-2 mm MSWI BA fraction were examined as binder materials. In addition, the effect of mechanical activation on BM-FA binder properties was tested.

Especially in the northern Europe and Scandinavia one of the significant features for hydraulically bound base course material is the low thermal conductivity and durability against frost. The base material used in the base course stabilization was mixture of recovered MSWI BA fractions 0-2 mm, 2-5 mm in 1:1 ratio and 0-2 mm, 2-5 mm and 5-12 mm fractions in 1:1:1 ratio. Stabilized test specimens were prepared in standard proctor mould and the effect of different binders were evaluated with unconfined compression strength (CEN ISO/TS 17892-7: fi), freeze-thaw durability test, thermal conductivity and water permeability (CEN ISO/TS 17892-11: fi).

Based on the laboratory tests the most potential by-product based binders were mechanically activated BM-FA and mixture of waste burnt lime and milled 0-2mm fraction of recovered MSWI BA. Especially mechanically activated BM-FA showed good compression strength and resistance against freeze-thaw cycles with high binder amount (>20 %). The relatively low thermal conductivities of the stabilized materials can reduce the needed structural thickness in the base courses if it is considered in frost dimensioning. By combining the various by-products and mechanical activation it is possible to efficiently utilize industrial by-products and achieve a well-functioning road structure. The solution mentioned above shall be tested in pilot construction during 2018.

_{Works cited: Lynn, C. J., Ghataora, G. S.,Dhir, R. K., 2017,  Municipal incinerated bottom ash (MIBA) characteristics and potential for use in road pavements, International Journal of Pavement Research and Technology, vol. 10 pp.185-201}