scholarly journals Behavior of compacted Ca-bentonite subjected to HMC loading: observations and interpretation

2021 ◽  
Vol 337 ◽  
pp. 04004
Author(s):  
Takayuki Motoshima ◽  
Sachie Iso ◽  
Tomoyoshi Nishimura
Keyword(s):  
Chemical Properties ◽  
Swelling Pressure ◽  
Simulation Models ◽  
Radioactive Waste Disposal ◽  
Physical Parameters ◽  
Unconfined Compression ◽  
Unconfined Compression Test ◽  
Sand Mixture ◽  
Pressure Test ◽  
Calcium Bentonite

This study presents result of HMC experimental test and discussions of chemical effort in Cabentonite. SWCC test, swelling pressure test and unconfined compression test as hydro-mechanical-chemical (HMC) test were applied to Cabentonite-sand mixture. Na-type bentonite has been studied to predict safety and confidence for artificial barrier layer consist of bentonite that many experimental research reports are represented, and can offer technology advanced comprehensive performance due to mathematical simulation models associated to physical parameters on thermal-hydration-mechanical-chemical properties. This study proposed a significant property for calcium bentonite to relate evaluating safety in radioactive waste disposal system, which emphasised much influence of suction and salinity chloride to hydration-mechanical behaviour for Calcium bentonite.

scholarly journals Performance of THM behavior of sand-bentonite mixtures considering thermal effect

2021 ◽  
Vol 337 ◽  
pp. 01020
Author(s):  
Tomoyoshi Nishimura ◽  
Junichi Koseki
Keyword(s):  
Compressive Strength ◽  
Relative Humidity ◽  
Compression Test ◽  
Unconfined Compressive Strength ◽  
Triaxial Compression ◽  
Radioactive Waste Disposal ◽  
Unconfined Compression ◽  
Unconfined Compression Test ◽  
Sand Mixture ◽  
High Level

This study presented the overview on the behavior of bentonite-sand mixture used in high level radioactive waste disposal. Both unconfined compression test and triaxial compression test were conducted out that unsaturated-saturated bentonite-sand samples were applied temperature effect below 100 degrees Celsius. Unconfined compressive strength was determined with various temperatures and different relative humidity for unsaturated bentonite-sand specimens, so the growing of pore pressure due to heating was most significant for interpretation to THM behaviour of artificial barrier system compositing bentonite materials.

Swelling pressures of compacted bentonites from diffuse double layer theory

2004 ◽  
Vol 41 (3) ◽  
pp. 437-450 ◽  
Author(s):  
Snehasis Tripathy ◽  
Asuri Sridharan ◽  
Tom Schanz
Keyword(s):  
Radioactive Waste ◽  
Double Layer ◽  
Expansive Soils ◽  
Chemical Properties ◽  
Weighted Average ◽  
Swelling Pressure ◽  
Radioactive Waste Disposal ◽  
Diffuse Double Layer ◽  
Barrier Materials ◽  
Double Layer Theory

The swelling pressures of several compacted bentonites (MX80, Febex, and Montigel) proposed for use as barrier materials in storing high-level radioactive waste in many countries were determined from the Gouy–Chapman diffuse double layer theory. The swelling pressures thus determined were compared with the reported experimental swelling pressures. The study revealed that, in general, at low compaction dry densities of the bentonites, the experimental swelling pressures are less than their theoretical counterparts, with the reverse trend at high compaction dry densities. Based on the reported experimental results for the three bentonites, relationships between the nondimensional midplane potential function, u, and the nondimensional distance function, Kd, were established. New equations for the swelling pressure were proposed on the basis of the diffuse double layer theory and the reported experimental data to compute swelling pressures of compacted bentonites. The suitability of the new equations was also verified with additionally reported experimental swelling pressures from three other bentonites (Kunigel V1, Kunigel, and bentonite S-2) that have been also proposed for use as barrier materials. Very good agreement was found in all the cases between the experimental swelling pressures and the swelling pressures obtained using the proposed equations. The use of the proposed equations is based on the weighted average valency of the cations present in bentonites, since the valency of the cations present has a significant influence on the swelling pressure.Key words: clays, compressibility, swelling pressure, expansive soils, chemical properties, radioactive waste disposal.

scholarly journals Anisotropic and age-dependent elastic material behavior of the human costal cartilage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Matthias Weber ◽  
Markus Alexander Rothschild ◽  
Anja Niehoff
Keyword(s):  
Costal Cartilage ◽  
Indentation Test ◽  
Biomechanical Properties ◽  
Material Behavior ◽  
Cartilage Tissue ◽  
Elastic Behavior ◽  
Unconfined Compression ◽  
Unconfined Compression Test ◽  
Young’S Moduli ◽  
Age Related

AbstractCompared to articular cartilage, the biomechanical properties of costal cartilage have not yet been extensively explored. The research presented addresses this problem by studying for the first time the anisotropic elastic behavior of human costal cartilage. Samples were taken from 12 male and female cadavers and unconfined compression and indentation tests were performed in mediolateral and dorsoventral direction to determine Young’s Moduli EC for compression and Ei5%, Ei10% and Eimax at 5%, 10% and maximum strain for indentation. Furthermore, the crack direction of the unconfined compression samples was determined and histological samples of the cartilage tissue were examined with the picrosirius-polarization staining method. The tests revealed mean Young’s Moduli of EC = 32.9 ± 17.9 MPa (N = 10), Ei5% = 11.1 ± 5.6 MPa (N = 12), Ei10% = 13.3 ± 6.3 MPa (N = 12) and Eimax = 14.6 ± 6.6 MPa (N = 12). We found that the Young’s Moduli in the indentation test are clearly anisotropic with significant higher results in the mediolateral direction (all P = 0.002). In addition, a dependence of the crack direction of the compressed specimens on the load orientation was observed. Those findings were supported by the orientation of the structure of the collagen fibers determined in the histological examination. Also, a significant age-related elastic behavior of human costal cartilage could be shown with the unconfined compression test (P = 0.009) and the indentation test (P = 0.004), but no sex effect could be detected. Those results are helpful in the field of autologous grafts for rhinoplastic surgery and for the refinement of material parameters in Finite Element models e.g., for accident analyses with traumatic impact on the thorax.

Swelling pressure and microstructure of an activated swelling clay with temperature

Clay Minerals ◽  
1998 ◽  
Vol 33 (2) ◽  
pp. 255-267 ◽  
Author(s):  
D. Tessier ◽  
M. Dardaine ◽  
A. Beaumont ◽  
A. M. Jaunet
Keyword(s):  
Room Temperature ◽  
Swelling Pressure ◽  
Radioactive Waste Disposal ◽  
Basic Medium ◽  
Hydraulic Pressure ◽  
Swelling Behaviour ◽  
Transmission Electron ◽  
Ca Ions ◽  
Na Ions ◽  
Marked Drop

AbstractClay from Fourges has been selected by the Commissariat à l'Energie Atomique as a support in radioactive waste disposal studies. This material was activated by adding Na2CO3, then compacted at 60 MPa. Subsequently, its swelling behaviour was monitored at 90°C and 145°C for 330 days and at the end of this period the samples were examined by transmission electron microscopy (TEM). For this, they were embedded in a resin then sectioned with an ultramicrotome for mineralogical and chemical analyses. The initial material is essentially composed of kaolinite and smectite. Addition of Na2CO3 at room temperature induces a replacement of Ca ions by Na ions and the precipitation of finely divided carbonates on the surface of the constituents. At the end of 330 days at 90°C under a hydraulic pressure of 1 MPa, the initial particles combine and the material exerts a swelling pressure of 20 MPa. A complete reorganisation of the clay crystallites is observed without significant dissolution of the solid phases. After the same time at 145°C under a hydraulic pressure of 10 MPa, in a basic medium, the combined conditions are such that a high proportion of the clay is dissolved with formation of amorphous aluminosilicates correlated with a marked drop in the swelling pressure to 5 MPa. This work establishes the advantages of following the macroscopic properties in parallel with the microstructure variations for understanding the changes in the properties of clays.

scholarly journals High-density bimodal bentonite blends for hydraulic sealings at the Ibbenbüren coalmine

Clay Minerals ◽  
2015 ◽  
Vol 50 (3) ◽  
pp. 391-403 ◽  
Author(s):  
Felicitas Wolters ◽  
Wiebke Baille ◽  
Katja Emmerich ◽  
Eva Schmidt ◽  
Christian Wolters ◽  
...  
Keyword(s):  
Swelling Pressure ◽  
Mining Area ◽  
Applied Strain ◽  
Sand Mixture ◽  
Pressure Tests ◽  
Pressure Development ◽  
Pressure Water ◽  
Sufficient Magnitude ◽  
Sealing Materials ◽  
Oedometer Tests

AbstractThe two high-pressure water-retaining dams at the Ibbenbüren coalmine in Münsterland (Germany) have to perform reliably under the induced tension caused by further exploitation of the current mining area. The load-bearing and the sealing functions of the new barriers were separated and new sealing materials were developed. An innovative multilayer sealing system of bentonite and sandwiched equipotential layers (SANDWICH) supporting homogeneous swelling and sealing, independent of formation water (Nüesch et al., 2002), was applied in this project. A testing program of strain-controlled swelling pressure tests on compacted bentonite specimens and on a bentonite/sand mixture was conducted to ensure an adequate potential for swelling-pressure development.The measurements under constant volume for dry densities between 1.45 g/cm3 and 1.67 g/cm3 showed an evolving swelling pressure between 1.04 and 1.8 MPa for 100% bentonite samples. Straincontrolled oedometer tests for zero strain and step-wise applied strain up to 2% revealed that a sufficient magnitude of swelling pressure existed at maximum applied strain.

Numerical Simulation of the Swelling Pressure Test on Compacted Boom Clay

2008 ◽  
Vol 8 (20) ◽  
pp. 3690-3696
Author(s):  
K. Bendani ◽  
N. Laredj ◽  
H. Missoum ◽  
H. Khelafi
Keyword(s):  
Numerical Simulation ◽  
Swelling Pressure ◽  
Boom Clay ◽  
Pressure Test

SOFT SOIL IMPROVEMENT USING CHEMICAL-RUBBER CHIPS MIXTURE

2015 ◽  
Vol 76 (2) ◽  
Author(s):  
Aminaton Marto ◽  
Norazirah Aziz ◽  
Mohammed Ridzuan Jahidin ◽  
Nor Zurairahetty Mohd Yunus ◽  
Fauziah Kasim ◽  
...  
Keyword(s):  
Void Ratio ◽  
Soft Soil ◽  
Soil Improvement ◽  
Soil Test ◽  
Unconfined Compression ◽  
Marine Clay ◽  
Untreated Sample ◽  
Unconfined Compression Test ◽  
Soft Soils ◽  
Clay Particles

Soft soils are widely found in many areas around the world as well as in Malaysia. Marine clay is one of the problematic soft soils. The marine clay should be pretreated before the construction to enhance the usability and serviceability of highway constructed on this type of soil. This paper presents the research results on the usability of chemical (SH-85)-rubber chips mixtures as the stabilizing agent in improving the characteristics of marine clay from two engineering perspectives; the strength and the compressibility. Three types of laboratory tests were conducted; index soil test, unconfined compression test and oedometer test. The results show that the treated samples had higher unconfined compressive strength compared to untreated sample. The strength of marine clay increased when the amount of the SH-85 increased.  The void ratio reduced in value when the chemical-rubber chips mixture was added to the marine clay. It is due to the chemical that acts as a binder that interlocks the rubber chips and the marine clay particles, reducing the compressibility. It has been concluded that the mixture of chemical-rubber chips with 8 % SH-85 plus 1 % of rubber chips is more effectively improved the characteristics of marine clay.  

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