Use of Cement-Chelated Solidified MSWI Fly Ash for Pavement Material: Mechanical and Environmental Evaluations

As a by-product from the incineration of Municipal Solid Waste (MSW), fly ash usually contains mobile heavy metals that may engender severe pollution for reuse. In this study, fly ash was solidified with cement and chelating agent to immobilize these polluting elements. The possibility of using the solidified fly ash for pavement materials was also assessed through mechanical and environmental perspectives. According to the results, the strength of solidified fly ash was found proportional to both the cement/fly ash ratio and curing time. This indicated that the increase of fly ash loading reduced the concentration of products from cement hydration, and thus destroyed the structure of products of hydration. With the increase of freeze-thaw cycles, the compressive strength of cement-stabilized fly ash decreased from 7 to 14 days, and then increased from 14 to 28 days. Subsequently, the finite element analysis showed that placing the solidified fly ash layer as pavement materials between unbound base course and subgrade was beneficial to prolong the fatigue life and reduce the rutting distress of asphalt pavements. Finally, the metals leachability of the mixtures was tested, which showed that leaching concentration decreased as the cement/ash ratio, curing time and chelating agent content increased.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author