Effects of ultrasonically dispersed nano-slurries on solid waste-based autoclaved concrete (SWAC) and its leaching of heavy metals

Abstract

The effects of three nano-slurries and nano-powders on the solid waste-based autoclaved concrete (SWAC) mainly from municipal solid waste incineration fly ash (MSWI) and fly ash (FA) were studied. Then leaching test of SWAC was further investigated. The results indicate that the ultrasonically dispersed nano-slurries promote the filling effect and nucleation of nanomaterials, which are more conducive to the formation of tobermorite. The intercalation of flaky tobermorite leads to a denser microstructure when nano-slurries are doped, and the compressive strength, water absorption and leaching of SWAC are substantially improved, especially for nano-CaCO₃, in which case the compressive strength increases by 32.0% and the water absorption decreases by 23.2%. In addition, the solidification rates of Pb, Cu and Zn can reach 90.5%, 91.5% and 83.3%, respectively, which is mainly because the hydrothermal treatment and nano-slurries can promote the formation of tobermorite that owns good ability to adsorb heavy metals in MSWI.

Keywords:

• reuse of solid waste
• autoclaved concrete
• nanomaterials
• hydrothermal treatment
• heavy metals
• tobermorite

Acknowledgment

The authors acknowledge the financial supports received from the National Key Research and Development Program of China (No. 2019YFE0112600) and the Science and Technology Innovation Action Plan of Shanghai of China (No. 19DZ1204900).

Disclosure statement

No potential conflict of interest was reported by the authors.