Evaluation of the ability of cement prepared with incineration fly ash to solidify heavy metals at high temperatures

Abstract

Scholars have demonstrated the feasibility of using incineration fly ash to prepare cement. Therefore, this article evaluated the performance changes and the ability to solidify heavy metals of cement prepared with the incineration fly ash after being exposed to fire (high temperature). The research results indicated that with the increase of incineration fly ash content, the mass loss of the cement prepared rose from 8.96% to 9.92%, and the strength loss increased from 63.91% to 92.73% after high-temperature treatment at 800 °C. Which proved that the incineration fly ash significantly weakened the performance of the cement after high temperatures, which was not conducive to the reuse of the components in cement. After high-temperature treatment, new phases - Lime and Tobermorite were generated, and the pore structure of cement was greatly changed, with a decrease in harmless pores. The content of harmful and multi-harmful pores exceeded 87%. A large amount of heavy metals evaporated, resulting in a decline of heavy metal content in cement. The leaching concentration of a few heavy metals in weak acid environments tended to increase, but it was still far below the limits specified in Chinese standards GB 5085.3-2007, GB 16889-2008, and GB 18598-2019. Therefore, the high-temperature treated cement still effectively solidified residual heavy metals, but it could not suppress the volatilization of heavy metals at high temperatures.