Geoenvironmental properties of industrially contaminated site soil solidified/stabilized with a sustainable by-product-based binder

Ya-Song Feng; Yan-Jun Du; Annan Zhou; Ming Zhang; Jiang-Shan Li; Shi-Ji Zhou; Wei-Yi Xia

doi:10.1016/j.scitotenv.2020.142778

Geoenvironmental properties of industrially contaminated site soil solidified/stabilized with a sustainable by-product-based binder

Sci Total Environ. 2021 Apr 15:765:142778. doi: 10.1016/j.scitotenv.2020.142778. Epub 2020 Oct 6.

Authors

Ya-Song Feng¹, Yan-Jun Du², Annan Zhou³, Ming Zhang⁴, Jiang-Shan Li⁵, Shi-Ji Zhou⁶, Wei-Yi Xia⁷

Affiliations

¹ Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 211189, China. Electronic address: fengyasong@seu.edu.cn.
² Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 211189, China. Electronic address: duyanjun@seu.edu.cn.
³ Civil and Infrastructure Engineering, School of Engineering, Royal Melbourne Institute of Technology (RMIT), Melbourne, Vic 3000, Australia. Electronic address: annan.zhou@rmit.edu.au.
⁴ Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1, Higashi, Tsukuba, Ibaraki 305-8567, Japan. Electronic address: m.zhang@aist.go.jp.
⁵ State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China. Electronic address: jsli@whrsm.ac.cn.
⁶ Jiangsu Key Laboratory of Urban Underground Engineering and Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 211189, China. Electronic address: shijizhou@seu.edu.cn.
⁷ Jiangsu Provincial Academy of Environmental Science, Nanjing 210036, China. Electronic address: xiaweiyi@seu.edu.cn.

PMID: 33127139
DOI: 10.1016/j.scitotenv.2020.142778

Abstract

This paper presents a study on utilizing a novel BCP binder, basic oxygen furnace slag (BOFS) activated with mixed calcium carbide residue (CCR) and phosphogypsum (PG), to solidify/stabilize heavy metals in industrial contaminated site soil. The effects of curing time and binder dosage on the geoenvironmental properties of the solidified/stabilized soil including soil pH, electrical conductivity, unconfined compressive strength, and leachability were tested and discussed. Chemical speciation of target heavy metals, pore-size distribution of treated soil, and phase identification of reaction products were analyzed to understand the mechanisms leading to the change of geoenvironmental properties. The results demonstrated that the addition of the BCP binder yielded remarkable increase in soil pH, unconfined compressive strength, and relative binding intensity index (I_R) of target heavy metals including nickel (Ni) and zinc (Zn), while significantly decreased the electrical conductivity and leachability of contaminated soil. The I_R value of heavy metals had a good linear relationship with the leached concentrations on a semi-logarithmic scale. The formation of heavy metal-bearing precipitates, absorptivity of calcium silicate hydrate (C-S-H), heavy metals encapsulation by C-S-H, and ion-exchange of heavy metals with ettringite (AFt) contributed to the immobilization of heavy metals in the solidified/stabilized soil.

Keywords: By-products; Contaminated soil; Heavy metal; Leachability; Solidification/stabilization; Unconfined compressive strength.