Dredged marine sediments stabilized/solidified with cement and GGBS: Factors affecting mechanical behaviour and leachability

Wan-Lu Zhang; Lun-Yang Zhao; Bryan A McCabe; Yong-Hui Chen; Liam Morrison

doi:10.1016/j.scitotenv.2020.138551

Dredged marine sediments stabilized/solidified with cement and GGBS: Factors affecting mechanical behaviour and leachability

Sci Total Environ. 2020 Sep 1:733:138551. doi: 10.1016/j.scitotenv.2020.138551. Epub 2020 Apr 8.

Authors

Wan-Lu Zhang¹, Lun-Yang Zhao², Bryan A McCabe³, Yong-Hui Chen⁴, Liam Morrison⁵

Affiliations

¹ Guangdong Engineering Center of Non-point Source Pollution Prevention Technology, Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-environmental Science & Technology, Guangdong Academy of Sciences, Guangzhou 510650, PR China; National-Regional Joint Engineering Research Center for Soil Pollution Control and Remediation in South China, Guangzhou 510650, PR China; Civil Engineering, School of Engineering and Ryan Institute, National University of Ireland, Galway H91TK33, Ireland.
² South China Research Institute on Geotechnical Engineering, South China University of Technology, Guangzhou 510641, China.
³ Civil Engineering, School of Engineering and Ryan Institute, National University of Ireland, Galway H91TK33, Ireland. Electronic address: bryan.mccabe@nuigalway.ie.
⁴ Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing, China.
⁵ Earth and Ocean Sciences, School of Natural Sciences and Ryan Institute, National University of Ireland, Galway H91TK33, Ireland. Electronic address: liam.morrison@nuigalway.ie.

PMID: 32422459
DOI: 10.1016/j.scitotenv.2020.138551

Abstract

Management strategies for the safe disposal of contaminated dredged marine sediment constitute a global-scale environmental issue. The stabilization/solidification method was investigated as a sustainable approach to the recycling of the sediment as a construction material. A systematic study of the factors affecting the mechanical performance and contaminant release was performed. The physico-chemical variables selected to assess the potential re-use of the sediment treated with Ordinary Portland cement (OPC) and Ground Granulated Blast Furnace Slag (GGBS) in an aquatic environment were: curing duration (7, 28, 56 and 98 days), curing temperature (5, 20 and 40 °C) and ambient (leachate) pH (1, 4, 7 and 10). Unconfined compressive strength (UCS) tests were conducted and extended-duration tank leaching tests were used to characterize the long-term leaching of Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Ba, Pb. The results showed that S/S methods provide excellent immobilization of metals in marine sediment at a pH range of 4 to 10. Immobilization efficiencies of >99.9% for Mn, Fe, Zn, As, Ba, Pb and >97.8% for Al, Cu and Zn are reported over 100 days. GGBS replacement is an effective way to further improve sediment properties by enhancing strength, mitigating sediment alkalization and offering a better immobilization capacity for Fe, Ni and Zn. The release of metals (Al, Mn, Cu, As, Ba and Pb) was strongly associated with a coupling effect of the physico-chemical factors, with metal-specific responses to curing temperature, curing duration and pH. Mn mobility showed a dramatic sensitivity to ambient pH while Ba was less pH-dependent. Al release is related to strength and leached out by dissolution in all situations considered. Considering that dredged marine sediments may contain multiple metal contaminants which exhibit individual responses to remediation, treatment with GGBS may be considered a potentially suitable management option.

Keywords: Leaching ratio; Marine dredged sediment; Tank leaching test; Unconfined compressive strength.