Exploring the Viability of Using WtE Incineration Ash as a Cement Replacement in Concrete

Abstract

The increasing importance of reducing greenhouse gas emissions demands new environmentally sustainable building materials. In the concrete industry most of the emissions comes from the production of cement. Research on materials that can be used as replacements for cement (SCMs) could help reduce the climate impact of the concrete industry. One of the possible SCMs that could be used are ash from WtE incineration. In this report the viability of the use of three different ash fractions from WtE incineration as cement replacement are be evaluated. These are a fly ash sample, an incinerator bottom ash sample and a mineral fraction incinerator bottom ash sample. Chemical and mechanical properties was evaluated using different techniques including a modified R3 method, compressive strength tests, PXRD and leaching tests with ICP-MS. It was found that all three of the ash fractions had chemical reactivity and the mechanical strength tests suggested that two of the ash fractions fly ash and MIBA had effect on the mechanical strength while the slag did not have ant effect. The results from the leaching tests were compared to thresholds on allowed limits of leaching from monolithic concrete samples and found to be below these thresholds. However, the limited knowledge and regulations on monolithic samples made the interpretation of these results difficult. The result from this thesis suggests that the use of WtE incineration ash a SCM is a possibility but that more research is needed. It is also concluded that the need for more and less complicated to understand regulations regarding leaching from monolithic concrete is needed in Sweden and that the current lack of regulations might be hindering the adoption of new sustainable building materials.