Impact of wetting-drying cycles and cracks on the permeability of compacted clayey soil

Louati, Fatma; Trabelsi, H.; Jamei, Mehrez; Taïbi, Saïd

doi:10.1080/19648189.2018.1541144

Cited by 28 publications

(11 citation statements)

References 57 publications

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“…Synthetic liners offer long-term impermeability to leachate but imply a high technology input and can be affected by slope stability, interface shear strength (Kavazanjian et al, 2006) and physico-chemical, thermal and mechanical problems (Kong et al, 2017), which may result in failure within 10 yrs of service (Rowe and Sangam, 2002;Rowe et al, 2003). Compacted clay liners are puncture-resistant and have advantageous reactive properties, but can be unstable in contact with leachate and susceptible to crack-ing under repeated wetting and drying cycles (Louati et al, 2018;Yesiller et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

The Role of Natural Clays in the Sustainability of Landfill Liners

2020

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Engineered synthetic liners on their own cannot protect the environment and human health against landfill leachate pollution. Despite their initial impermeability, they are susceptible to failure during and after installation and have no attenuation properties. Conversely, natural clay liners can attenuate leachate pollutants by sorption, redox transformations, biodegradation, precipitation, and filtration, decreasing the pollutant flux. Depending on the clay, significant differences exist in their shrinkage potential, sorption capacity, erosion resistance and permeability to fluids, which affects the suitability and performance of the potential clay liner. Here, the physico-chemical, mineralogical and geotechnical characteristics of four natural clayey substrata were compared to discuss their feasibility as landfill liners. To study their chemical compatibility with leachate and rainwater, hydraulic conductivities were measured every ≈2 days spread over 7 weeks of centrifugation at 25 gravities. At field-scale, this is equivalent to every 3.4 yrs spread over 80 yrs. All the clayey substrata had favourable properties for the attenuation of leachate pollutants, although different management options should be applied for each one. London Clay (smectite-rich) is the best material based on the sorption capacity, hydraulic conductivity and low erodibility, but has the greatest susceptibility to excessive shrinkage and alterable clay minerals that partially collapse to illitic structures. Oxford Clay (illite rich) is the best material for buffering acid leachates and supporting degradation of organic compounds. The Coal Measures Clays (kaoline-rich) have the lowest sorption capacity, but also the lowest plasticity and have the most resistant clay minerals to alteration by leachate exposure.

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Section: Introductionmentioning

confidence: 99%

The Role of Natural Clays in the Sustainability of Landfill Liners

2020

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“…high specific surface area (SSA), cation exchange capacity (CEC), and absorption) which enhance the attenuation of inorganic contaminants in landfill leachate by filtration, sorption, biodegradation and precipitation reactions (Allen, 2001;Allen and Taylor, 2006). However, clays can have high plasticity, which may result in large volume changes due to swelling and shrinkage upon uptake and removal of water or contact with high ionic strength liquids, such as leachate (Louati et al, 2018;Yesiller et al, 2000). This can lead to increased leakage through compacted clay liners.…”

Section: Natural Clay Substratamentioning

confidence: 99%

“…The high plasticity (CH in the Unified Soil Classification System, USCS) when applying the BS 1377:2 (1990) of the Oxford and London clays implies a susceptibility to cracking and slope and landsides failure; thus they are unsuitable as a bottom liner per se (Louati et al 2018, Wagner 2013Yalcin 2007). However, London Clay is the best material regarding the sorption capacity and low erodibility, and Oxford Clay is the best regarding the acid buffering and organic degradation properties.…”

Section: Additives Recycled From Industrial Process Residuesmentioning

confidence: 99%

“…A major limitation of the containment strategy is that final stabilisation of the waste is prolonged and the contaminating potential of leachate is maintained, potentially beyond the design life of the control systems, to create a long-term environmental risk. Failure of the liner components in <10 yrs by different mechanico-chemical mechanisms is common (Louati et al, 2018;Rowe and Sangam, 2002;Yesiller et al, 2000). Diffusion of contaminants through clay liners due to the high concentration gradient and persistent source in the leachate remains a key problem causing liner failure in the long term (Chen et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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High Attenuation Recycled Materials as landfill liners (the HARM project) – A new concept for improved landfill liner design

Regadío¹,

Cargill²,

Black³

et al. 2020

Preprint

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A new approach in landfill liner design which combines hydraulic containment of leachate with contaminant attenuation to improve the performance of these environmental control systems at landfills is described. The idea is to re-use readily available industrial waste residues (construction and biomass waste) as additives for natural clay liners, wherein the additives have specific properties which enhance the attenuation of contaminants by the mixture. The aim is to (1) evaluate the contaminant attenuation capacity of these mixtures, (2) develop design guidelines to construct liners for waste containment systems and similar applications, and (3) interpret their performance using numerical modelling. This is evaluated in permeation studies using a geotechnical centrifuge, which enables the performance of liner compositions to be tested for representive time-scales (100 years), pressures and temperatures at realistic experimental time-scales of days-weeks in the laboratory. The permeation experiments include liner compositions flushed with leachate to deduce contaminant transport and attenuation mechanisms, followed by rainwater to assess the potential for release of attenuated contaminants. This experimental methodology is illustrated with depth profiles from permeation studies conducted on different clay-additive compositions. The concept will be applicable for liner design at other waste disposal facilities and is a timely improvement which addresses the problem of managing large quantities of industrial residues. Instead of disposal these can be recycled as an additive in host clay to construct these liners, thus conserving natural resources (clay) and reducing construction costs. It also provides an effective and more environmentally sustainable basis to reduce risks from leachate leakage.

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“…During construction or production, the compacted clay produces a variety of changes in properties, the most obvious of which is the formation of fractured clay 1 – 4 . Fractured clay has great irregularity and unpredictability, that is, there are fractures that run through the entire clay layer or there are non-penetrating fractures that partially penetrate the clay 5 , 6 .…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical simulation of solute transport in non-penetrating fractured clay

Shen

et al. 2022

Sci Rep

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A set of one-dimensional experimental device for solute transport in non-penetrating fractured clay are developed, which can study the laws of groundwater flow and solute transport under different hydraulic heads, fractured aperture, and thickness of non-penetrating zones. The experimental results show that the solute will quickly reach the bottom of the clay along the non-penetrating fracture, and there is an obvious dominant flow phenomenon compared with the intact clay. According to the experimental data and numerical calculation results, the model parameters of the fracture and each soil layer were identified, and the verified numerical model was used to simulate the solute transport in the non-penetrating fractured clay. The numerical results show that the increase of the thickness for the non-penetrating zone has a significant improvement on the anti-seepage ability of clay, and the increase of the hydraulic head pressure and fractured aperture leads to a faster growth rate of the solute concentration, which indicates that the solute breaks down the lower impermeable clay layer under high head pressure. The research results are of great significance for the bottom anti-seepage layer similar to landfill projects.

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Impact of wetting-drying cycles and cracks on the permeability of compacted clayey soil

Cited by 28 publications

References 57 publications

The Role of Natural Clays in the Sustainability of Landfill Liners

The Role of Natural Clays in the Sustainability of Landfill Liners

High Attenuation Recycled Materials as landfill liners (the HARM project) – A new concept for improved landfill liner design

Experimental and numerical simulation of solute transport in non-penetrating fractured clay

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