On the reliability of reusing bottom ash from municipal solid waste incineration as aggregate in concrete

The present work concerns an experimental investigation on the use of residues derived from fluidized bed incinerators as aggregates for concrete. Concrete mixtures were obtained from conventional mix designs used in the production of unreinforced precast elements by partial replacement of natural aggregates with recycled components. The characterization was performed by means of physical and mechanical tests according to the prescriptions of the Italian technical code for construction, with special attention to the probabilistic evaluation of the compressive strength and an investigation of the tensile behavior of the considered specimens. The simplified statistical analysis shows that mixtures containing recycled aggregates may achieve characteristic values of the compressive strength that are very close to the performance of conventional mix designs that are commonly used in the investigated applications. The average compressive strength and the material reliability, i.e., the scattering of results, of concretes containing recycled aggregates are both comparable with those of the reference concrete. Conversely, an investigation on the tensile strength points out a lower performance for mix designs including recycled aggregates. In both cases, the adoption of 42.5R cement is found to remarkably improve experimental results, i.e., to reduce the gap between the performance of concretes containing recycled aggregates and the reference concrete.