Use of MSWI fly ash for the production of lightweight artificial aggregate by means of innovative cold bonding pelletization technique. Chemical and morphological characterization

Cement-based cold bonding pelletization process has recently gained relevant consideration in literature mostly due its suitability for the manufacture of artificial aggregates. An extensive study on the recovery of municipal solid waste incinerator fly ash is investigated. Such material is classified as hazardous and it needs a treatment to be used or landfilled. The examined fly ash from waste incineration plant were subjected to cold bonding pelletization process by using cement, lime and coal fly ash as binders to achieve their stabilization/solidification. Several mixtures were prepared employing different weight amounts of ash from 50% to 70%. A further pelletization step was performed using only cementitious binders in order to reach satisfactory immobilization levels. Lightweight porous aggregates with good properties in terms of density, water absorption and crushing strength were obtained from this process. The results consider these materials suitable for the recovery in the field of building materials. The same process was also tested on concrete specimens manufactured with the same aggregates. The results showed a lightweight concrete having average performance and mostly suitable for applications where high performance are not necessary.