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Thematic Session 32

Clays in geotechnical applications

Jaak J.K. Daemen Department of and Metallurgical Engineering, University of Nevada-Reno, Reno, Nevada, USA [email protected]

Haluk Akgün Department of Geological Engineering, Middle East Technical University (METU), Çankaya, , [email protected]

Mustafa Kerem Koçkar Department of , Hacettepe University, Çankaya, Ankara, Turkey [email protected]

Clayey , clay-soil and clay minerals play a very important role in geotechnical applications since clay in general has a low strength, high compressibility, high plasticity, high swelling potential and relatively low coefficient of permeability. These geotechnical properties of clay almost always need to be improved prior to its use in geotechnical projects related to highway construction, , slurry , liner, and underground waste repository sealing as as in the oil industry. Since clay minerals are electrochemically active, they affect the soil microstructure and hence, it is also very important to understand the relationship between clay mineralogy and geotechnics. This session seeks contributions to aid in understanding the improvement of the geotechnical properties of clayey , clay-soil/rock mixtures (i.e., -, bentonite-crushed rock, mixtures of clay and various material(s), etc.) and clay minerals in geotechnical projects related to highway construction, dam, slurry trench, , underground waste repository sealing and oil industry utilized bentonite/ along with understanding the relationship between clay mineralogy and geotechnics. Improvement of the geotechnical properties might involve a decrease/increase in plasticity and swelling potential, an increase in strength that increases workability, a decrease in the coefficient of permeability, etc.

Keywords: Clay geotechnics, Clay barriers in , Clay in sealing waste repositories, Clay mineralogy- geotechnics relationship, Clay geotechnics in the oil industry.

Potential Journals: Applied Clay Science, Clays and Clay Minerals, Clay Minerals.

a) b) 14 700

12 FS = 0.12e0.02 (SSA) 600 Relationships between a) FS ) SP = 1.21e0.03 (SSA) % r² = 0.84 ( 500 10 r² = 0.96 and SSA, b) SP and SSA, c) , FS , 8 400 FS and w/c, d) SP and w/c, e)

6 300

Pressure, SP (kPa) SP Pressure, Swelling

4 200 FS and SKR, f) SP and SKR. Free Free

2 Swelling 100 SSA: specific surface area, 0 0 0 50 100 150 200 250 0 50 100 150 200 250 FS: free swelling, SP: swelling SSA (m2/g) SSA (m2/g)

c) d) pressure, w/c: , 14 700 FS = 0.89 (w/c) - 20.53 SKR: smectite/ ratio 12 600 SP = 42.06 (w/c) - 10.2 r² = 0.87 r² = 0.93 10 500 for Orta clay, Çankırı, Turkey 8 400 (Source: Akgün, H., 6 300 4 200 Türkmenoğlu, A.G., Kelam,

Free Swelling, FS FS (%) Swelling, Free 2 100

Swelling Pressure, SP (kPa) SP Pressure, Swelling A.A., Yousefi-Bavil, K., Öner, 0 0 0 10 20 30 40 0 10 20 30 40 G., Koçkar, M.K., 2018, Water Content, w/c (%) Water Content, w/c (%) Assessment of the effect of e) f) 14 700 mineralogy on the FS = 5.63 (SKR) - 4.50 SP = 292.41 (SKR) - 306.93 12 600 r² = 0.74 r² = 0.86 geotechnical parameters of 10 500 8 400 clayey soils: A case study for 6 300 the Orta County, Çankırı, 4 200

Free Swelling, FS FS (%) Swelling, Free Turkey, Applied Clay Science,

2 (%) SP pressure, Swelling 100 0 0 164:44-53. 0 1 2 3 4 0 1 2 3 4 Smectite/Kaolinite Ratio (SKR) Smectite/Kaolinite Ratio (SKR)

An example of conceptual design of (a) used fuel container, (b) engineered barrier in the emplacement room of a (c) underground nuclear waste disposal repository, often referred to as deep geological repository (DGR) (Witherspoon PA, Bodvarsson GS (2006) Geological (a) (b) challenges in radioactive waste isolation: fourth worldwide review, Sciences Division, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California, Publication LBNL- 59808) as quoted by Akgün, H. and Koçkar, M.K., 2018, Evaluation of a sand bentonite as a shaft/ sealing material, Applied Clay Science, 2018, 164: 34-43.

(c)