Using alkali-activated dredge sludge ash-bentonite for low permeability cutoff walls: The engineering properties and micromechanism

• DOI: 10.1016/j.eti.2023.103060
• Publication Date: 2023-02-10T23:01:57Z
• Authors: Xinminnan Hui; Yong Wan; Xingxing He; Jiang-shan Li; Xiao Huang; Lei Liu; Qiang Xue
• Keywords: Bentonite; Calcium silicate hydrate; Ettringite

Although vertical cutoff walls can effectively contain groundwater pollution, barriers constructed using conventional cement-bentonite-soil (CBS) mixtures exhibit poor permeability and produce considerable CO2 during cement production. The dredged sludge ash (DSA) has potential to be used as an eco-friendly source for building because of the remarkable pozzolonicity. In this study, a mixture consisting MgO-activated bentonite was develop low permeable DSA-bentonite-sand (MDBS) barrier material application walls. mechanical properties MDBS CBS were investigated hydration products microstructure examined scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDS), diffraction (XRD), mercury intrusion porosimetry (MIP). results showed that exhibited excellent impermeability: hydraulic conductivity cured 60 d reached minimum (1.83 × 10−8 cm/s), considerably superior common requirement (lower than 10−7 cm/s) unconfined compressive strength increased by approximately 112% compared samples only 7 d. in mainly magnesium silicate hydrate hydrotalcite, which filled pores more (calcium calcium hydroxide ettringite). products, swelling, pore size distribution determined permeability. It is verified activated dredge ideal instead cement.