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Geomechanics and Engineering
  Volume 31, Number 3, November10 2022 , pages 305-318
DOI: https://doi.org/10.12989/gae.2022.31.3.305
 


An assessment of the mechanical behavior of zeolite tuff used in permeable reactive barriers
Gökhan Çevikbilen

 
Abstract
    Permeable reactive barriers used for groundwater treatment require proper estimation of the reactive material behavior regarding the emplacement method. This study evaluates the dry emplacement of zeolite (clinoptilolite) to be used as a reactive material in the barrier by carrying out several geotechnical laboratory tests. Dry zeolite samples, exhibited higher wetting-induced compression strains at the higher vertical stresses, up to 12% at 400 kN/m2. The swelling potential was observed to be limited with a 3.5 swell index and less than 1% free swelling strain. Direct shear tests revealed that inundation reduces the shear strength of a dry zeolite column by a maximum of 10%. Falling head permeability tests indicate decreasing permeability values with increasing the vertical effective stress. Regarding self-loading and inundation, the porosity along the zeolite column was calculated using a proposed 1D numerical model to predict the permeability with depth considering the laboratory tests. The calculated discharge efficiency was significantly decreased with depth and less than 2% relative to the top for barrier depths deeper than 20 m. Finally, the importance of directional dependence in the permeability of the zeolite medium for calibrating 2D finite element flow analysis was highlighted by bench-scale tests performed under 2D flow conditions.
 
Key Words
    clinoptilolite; hydro-compression; permeability; permeable reactive barrier; shear strength; zeolite
 
Address
Gökhan Çevikbilen: Department of Civil Engineering, Istanbul Technical University,ITU Ayazaga Campus, Faculty of Civil Engineering, Room 140413, Sar
 

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