Hydraulic performance of activated calcium bentonite treated by polyionic charged polymer

Razakamanantsoa, Andry; Barast, Gilles; Djéran-Maigre, Irini

doi:10.1016/j.clay.2012.01.022

Cited by 57 publications

(15 citation statements)

References 32 publications

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“…In order to investigate the impact of Pb concentrations on hydraulic conductivity of conventional back lls SB, the MFP tests on SB specimens permeated with Pb(NO 3 ) 2 solution with 0 to 50 mM (0, 5,10,15,20,30,40, and 50 mM) were conducted, and the applied pressure was 100 kPa.…”

Section: Relationship Between Hydraulic Conductivities and Pbmentioning

confidence: 99%

“…Polymers as additives used in modifying bentonite have been investigated for improving the hydraulic performance of bentonite-rich barriers [11][12][13][14][15][16]. Several kinds of polymermodified bentonite have been developed, including but not limited to HYPER-Clay, dense prehydrated GCLs (DPH-GCL, polymer-modified bentonite plays an important role in GCL), and BPC [12,14,[17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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Hydraulic Conductivity of Polymer-Amended Sand-Bentonite Backfills Permeated with Lead Nitrate Solutions

Shen

Wei

2018

Advances in Civil Engineering

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Hydraulic conductivity of sand-bentonite (SB) backfills amended with polyanionic cellulose (PAC) to lead nitrate (Pb(NO3)2) solutions was evaluated experimentally in this study. PAC-amended sand-bentonite (PSB) backfills were synthesized by mixing sand-bentonite mixture with 0.3 to 1.2% dry PAC (by total dry mixture mass) and mixed with a certain weight of conventional bentonite (CB) slurry. The rheology properties including the filtrate loss, viscosity, density, and pH testes of slurry with various bentonite dosages were measured to determine the reasonable CB dosage of slurry. The slump tests on PSB backfills with various mass slurries were conducted to determine the corresponding water content of backfills with slump 125 ± 5 mm. Under the applied pressure 100 kPa, the hydraulic conductivity to Pb(NO3)2 solutions (kc) of PSB backfills with various PAC contents was evaluated based on the modified filter press (MFP) tests, to ascertain the optimum PAC content of PSB backfills when permeated with Pb(NO3)2 solutions. Index properties, including the specific gravity (Gs) and liquid limit (wL) of PSB backfills, were measured after MFP tests. The MFP tests for PSB backfills were then conducted under various applied pressures to obtain the relationship between void ratio (e) and hydraulic conductivity of backfills. Finally, the flexible-wall permeability test (FWP test) under osmotic pressure 100 kPa was conducted to verify the effectiveness of the MFP test. The results indicate that slurry with 8% bentonite dosage is the reasonable choice in slurry wall construction. PSB has lower GS and higher wL compared to SB; increasing Pb concentration leads to GS of PSB increased and wL of PSB decreased. PSB with 0.6% PAC content is supposed as the optimum proportion of backfills when permeated with concentrated Pb(NO3)2 solution. PAC adsorbs large amount of bound water, which leads to higher water content (w) and e of PSB backfills, while lead ions (Pb) cause the diffuse double layer (DDL) of bentonite compressed and e of PSB backfills reduced. The kc of PSB-0.6 remains lower than 10−9 m/s and increases less than 10 times though the Pb concentration was up to 500 mM, demonstrating that the hydraulic performance of backfills can be improved effectively in Pb(NO3)2 solution by the additive PAC. The comparison results between k from MFP tests and FWP tests show that the MFP test is an effective and easy evaluation of hydraulic conductivity of backfills.

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Section: Relationship Between Hydraulic Conductivities and Pbmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hydraulic Conductivity of Polymer-Amended Sand-Bentonite Backfills Permeated with Lead Nitrate Solutions

Shen

Wei

2018

Advances in Civil Engineering

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“…1 and 2% cationic polymer amounts in terms of dry mass was added to the bentonite-polymer mixture, respectively. Afterwards, the mixture was taken in a polyethylene bottle and the mixture was shaken by for 5 min and remained in the bottle for almost 24 h to obtain a homogenous structure [12]. Finally, the polymer-treated GCLs were manufactured similarly with the GCLs that were assembled without polymer treatment.…”

Section: Methodsmentioning

confidence: 99%

“…Cationic polymer-treated bentonite specimens were prepared by measuring the mass of the polymer as 1 and 2% in the bentonite-polymer mixture [12]. After pouring all of the bentonite or bentonite-polymer mixture into the burette filled with the permeation fluid, the swell index was measured after 24 h for the bentonite specimens without polymer treatment and after 72 h for the bentonite specimens with polymer treatment due to the longer period for the swelling of polymer-treated bentonite specimens [1].…”

Section: Free Swell Testsmentioning

confidence: 99%

Problems and solutions for GCLs used in waste containment facilities: temperature concerns and polymer treatment related to GCLs used in waste containment areas

Ozhan

2017

Innov. Infrastruct. Solut.

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In this study, first, various geosynthetic clay liner (GCL) application areas were briefly defined and afterwards, the details of GCL usage in mine applications were given. GCLs are barrier materials that are preferred in mining facilities such as heap leach pads, tailing dams or waste landfills. In these applications, GCLs might be in contact with aggressive leachates that could deteriorate the hydraulic properties of the GCLs. The hydraulic capability of the GCLs is decreased by an increase in hydraulic conductivity or a decrease in swell index of the bentonite component of the GCL. Due to the biodegradation of the organic substances in a waste containment area, heat is generated and the temperature of the leachates increases. To investigate the effect of temperature, triaxial permeability and free swell tests were conducted on the GCLs that were permeated with 0.5 M MgCl 2 solution and deionized water. The temperature of the permeation fluid was chosen as 20 and 40°C. Furthermore, a cationic polymer having 1 and 2% amounts of mass was added to the bentonite component of the GCL to enhance the hydraulic capability of the GCL. Test results indicated that temperature increase in 0.5 M MgCl 2 solution from 20-40°C caused both an increase in the swell index and the permittivity of the GCLs. The increase in permittivity could be attributed to the lower viscosity of the fluid at higher temperatures. Finally, adding a cationic polymer up to the amount of 2% by mass to the bentonite resulted in almost two orders of magnitude decrease in the permittivity of the GCLs that were permeated with 0.5 M MgCl 2 solution. In conclusion, cationic polymer-treated GCLs might be used effectively in waste containment facilities by both decreasing the permittivity and increasing the swell index of the GCLs.

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“…In the tetrahedral silica sheet and octahedral alumina sheet of montmorillonite, some Si 4+ and Al 3+ are exchanged with Al 3+ and Mg 2+ , respectively [3] [4] [5]. As a result, surface of silica and alumina sheets has negative charges [6] [7]. These negative charges are balanced by cations, such as Ca 2+ or Na + , intercalated between the structural platelets/sheets.…”

Section: Introductionmentioning

confidence: 99%

The Aggregation of Bentonite Using Poly(N-isopropylacrylamide) as a Flocculant

Nakamura¹,

Murakami²

2018

MSCE

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Sedimentation tests of bentonite suspension were carried out by adding various concentrations of poly(N-isopropylacrylamide) (PNIPAM) with different molecular weights as flocculant below and above lower critical solution temperature (LCST). Also, the effect of PNIPAM on aggregation of bentonite was investigated by sedimentation rate, turbidity of supernatant. Additionally, XRD patterns and SEM photographs were measured in order to consider aggregation mechanism of PNIPAM. The sedimentation rate and turbidity for the PNIPAM with large molecular weight or PNIPAM solution of high concentration above LCST were faster and clearer than those with small molecular weight or low concentration. From XRD patterns, the peak of bentonite sediment with PNIPAM shifted to the low-angle side, suggesting that a part of PNIPAM chain entered between bentonite layers. Furthermore, it was confirmed by SEM photographs that PNIPAM covered bentonite surface after sedimentation test. It was indicated that PNIPAM adsorbs on the bentonite surface and aggregates each bentonite particle above LCST. From these results, PNIPAM works as a flocculant and the PNIPAM with large molecular weight has a good ability.

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Hydraulic performance of activated calcium bentonite treated by polyionic charged polymer

Cited by 57 publications

References 32 publications

Hydraulic Conductivity of Polymer-Amended Sand-Bentonite Backfills Permeated with Lead Nitrate Solutions

Hydraulic Conductivity of Polymer-Amended Sand-Bentonite Backfills Permeated with Lead Nitrate Solutions

Problems and solutions for GCLs used in waste containment facilities: temperature concerns and polymer treatment related to GCLs used in waste containment areas

The Aggregation of Bentonite Using Poly(N-isopropylacrylamide) as a Flocculant

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