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.