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Transcript of Faculty of Civil Engineering Laboratory (LEGHYD) Laboratory (LEGHYD) University of Sciences and...
Faculty of Civil Engineering Laboratory (LEGHYD)
University of Sciences and Technology
Houari Boumediene USTHB/ Algeria
ICCGE 2015 : 17th International Conference on Civil and Geological Engineering
Istanbul , Turkey, August 17 - 18 , 2015
Valorization of Local Materials in the Waterproofing Technique
of Landfills Site "TLS"
M. Debieche, F. Kaoua
Objectifs of the presentation
Valuation of two Algerian materials
Study of water and mechanical behavior of a compacted mixture of a pulverulent material (sand) and bentonite
Location map of the bentonite deposit in Algeria
The primary interest for environment protection increases the requirement of high quality and reliable sealing systems, whose the main characteristics sought are:
1) A maximum dry density of the compacted mixtures sand / bentonite.2) A low hydraulic conductivity (K ≤ 10-9m/s), to minimize leakage using a small percentage of bentonite. 3) A sufficient shear strength to maintain slope stability of the TLS. 4) The sustainability of the mixture should be checked vis-a-vis the climate
changes, in consecutive hydration properties over time (cycles of wetting-drying).
Category SiO2 (%) Al2O3% MgO% Na2O% CaO% Viscosity
Drilling mud 50 to 65 15 to 25 2 - 3 >2 < 1 ≥ 30
Foundry 50 to 65 15 to 25 2 - 3 - - -
Discoloring earth
50 to 65 15 to 25 3 - 5 - < 1 -
Pelletizing 50 to 65 15 to 25 2 - 3 > 1 - -
Criteria for the Selection of Compounds the Bentonite
Some Worlwide Bentonites Algerian Bentonite
* Kutch Inde %
S&B Greece %
Wyoming Federal%
Wyoming Black hill %
South of the USA%
Bentonite of Maghnia %
SiO2 45.43 60.83 58.14 66.12 59 64.98Al2O3 16.4 17.9 21.73 17.01 18.4 16.08Fe2O3 14.05 4.34 2.46 2.46 5.1 2.93CaO 1.18 1.9 0.86 1.37 3.88 0.61MgO 2.43 2.83 2.42 1.51 2.86 3.51K2O 0.13 1.98 0.52 0.54 0.78 2.02
Na2O 3.1 2.96 2.08 2.02 0.41 3.88TiO2 1.86 / / / / 0.20
Loss on ignition
13.28 6.44 5.3 7.3 8.31 6.07
Comparison of Chemical Compositions of the Worldwide and Algerian Bentonite
X-ray diffraction pattern of the bentonite of Maghnia
Photography of the Microstructure Bentonite of Maghnia
Designation Identification Bentonite of Maghnia
Natural water content (%)(1) 8,5Specific density of solid grains. Gs (2) 2.72Percentage of particles< à 80µm (3) 100
Percentage of particles C2< à 2µm (3) 42.5Liquidity limit. Wl(%) (4) 240Plasticity limit Wp(%) (4) 43Plasticity index Ip (%) (4) 197
Consistency index Ic (%) (4) 1.18Withdrawal limit Lr (%) (5) 10.24Withdrawal index Ir (%) (5) 229.76
Activity (%) Ac (6) 6.06Free swelling (ml) (7) 35
Value of methylene blue test (8) 18.75specific area(m2/g) (9) 394
pH(10) 10.3
Results of Identification Tests of the Studied Bentonite
Designation Identification Sand of Baghlia
Percentage of particles< à 80µm (3) 0.25Specific density of solid grains Gs (2) 2.65
Effective diameter (mm) D10 (3) 0.26Uniformity coefficient Cu (3) 3.46Curvature coefficient Cc (3) 0.98
Equivalent of sand ES (%) (11) 97Value of methylene blue test (8) 0.012
Results of Identification Tests of the Studied Sand
Grain-Size distribution curves of two materials used in this study
Dry density versus the water content for different concentrations of bentonite
Optimal water content versus concentration of bentonite
Evolution of maximum dry density versus concentration of bentonite
The effect of cycles of climatic variation on sand-bentonite mixtures
Hydraulic conductivity versus the bentonite content
Mohr-Coulomb straight intrinsic for different percentages of bentonite (CD)
Mohr-Coulomb straight intrinsic for different percentages of bentonite (UU)
The hydraulic conductivity and friction angle according to the bentonite percentages.
CONCLUSIONThe performed tests on S/B mixtures, allowed us to draw up the following conclusions:
The content of the optimal water content of the mixtures depends on the increase of the bentonite concentration.
A very low value of permeability (of the order of 10- 11 m /s), is achieved by introducing of only 6 % of SB. This is explained by a high specific area, an index fairly high plasticity, and a high rate of swelling SB from Maghnia, and therefore a greater of the adsorption capacity.
During the "wetting-drying" cycles, the SB mixtures exhibit good durability vis- a-vis the climatic variations due to the self-healing of this one.
The adding of the SB to the sand generates a reduction of the friction angle (φ) and an increase in the cohesion (C).
Due to the availability of materials in Algeria, its proper behavior towards mechanical, hydraulic and climatic constraints, the optimal mixture is the one compound of 6% of SB, which bestows a dual economic and ecological advantage, for waterproofing systems in coverage or at the bottom of the waste disposal centers.