June 2014 The physics of clay minerals: From the nano-scale to the geo- scale, and everything in between Jon Otto Fossum Laboratory for Soft and Complex Matter Studies NORWAY Bio- Geo- inspired Materials science Question: What is the first that comes to your mind when I say the word: Clay? MUD? Clays in ART The oldest surviving piece of art: The oldest sample known of baked clay: Figurine: "Venus of Vestonice" Found in 1920 in the Czech Republic. Approximate age: 23000 B.C. (Dated from mammoth bone ash in the clay) Clay avalanches No rwe g ia n G e o te c hnic a l Institute Clay avalanche: Rissa Norway 1978 Observation: Extreme mechanical instability of certain clayey RISSA soils, under given humidity conditions Example: the Rissa landslide (1978, near Trondheim, Norway) 3 Triggered by the excavation of 1000 m prior to building a barn Duration: 6 min 3 7 to 8 millions m of soil were displaced 40 persons were taken, 1 died 7 farms were rammed 33 ha of lands were touched A linear length of 80 m of coast ended up in the fjord The slope was very moderate The na tural quic k c la ys we re se dime nte d a t the e nd of the la st ic e a g e , c ommonly a t rive r mo uths in sa lty wa te r. The spe c ific ity of the na tural quic k c la ys is tha t the sa lt ha s be e n wa she d a wa y by wa te r ove r time , whic h ha s we a ke ne d the c ohe sion of the ma te rial. “House of c a rd” struc ture? : ~1 µm Clays are nano-/micro-particles: Two basic forms at nano-/micro-scale: 100 nm thick nanolayered particles 1 nm thick ”nanocards” ”decks of nanocards” (Bentonite/Laponite) (Kaolinite) ~ µm ,Aluminum ~ µm Qx-(Al3-xMgx)Si4O10(OH)2 DLVO Theory: vdW + Screened Electrostatic Rep. From J. Israe la c hvili Temperature effects: WAXS + SAXS + Rheometry Simple analog landslide experiments Q uic kc lay a nd Landslide s o f Claye y Soils, A.Kha ldo un, P.Mo lle r, A. Fall, G.We gdam,B. De Lee uw, Y. Me he ust, J.O . Fossum, D. Bo nn, Géosciences Re nne s 1, Unive rsity o f Amste rda m, ENS-Pa ris, NTNU-Tro nd he im Physical Review Letters 103, 188301 (2009) Shear stress imposed by gravity: (null at the free surface) All material above the yield surface is expected to flow ? ~1 µm Analog laboratory landslide experiments 56% 58% 61% 63% Weight% clay Quasi-newtonian flow Analog laboratory landslide experiments (3) 56% 58% 61% 63% 56% 58% 61% 63% Weight% clay Yield stress fluid flow Analog laboratory landslide experiments 56% 58% 61% 63% Weight% clay Landslide regime = flow on a thin lubrication layer ⇒ This is why the Rissa farm buildings remained upright ? Analog laboratory landslide experiments 56% 58% 61% 63% Weight% No flow clay No flow: steric hindrance of particle alignment? Similar to that observed in earlier study on bentonite/montmorillonite muds (Coussot, P., N. Roussel, S. Jarny, and H. Chanson: Continous or catastrophic solid-liquid transition in jammed systems, Phys. Fluids, 17, 011,704 (2005)) In addition: Preparation of a synthetic quick clay Composition: illite + bentonite + salt Illite is washed to remove any salt 3% of washed bentonite (swelling clay) Controlled additionIllite is washed of salt andso as measure to remove of the any elastic salt modulus as a function of the salt concentration3% of washed bentonite (swelling clay) Controlled addition of salt and measure of the elastic modulus as a function of the salt concentration Our conclusions (so far) regarding quick clay materials science and avalanches: A material containing more water is not necessarily more unstable For a limited range of water contents, the slide can occur on a very thin lubrication layer (lubrication layer/threadmill effect) This occurs when the material's yield stress is larger than a critical value that can be related to a simple theoretical model including the volume of the sample It is possible to prepare in the laboratory a synthetic material that has the same mechanical properties as the natural quick clay: A small amount of swelling (smectite) clay is essential for the behavior observed Appropriate question: Did we really study the “native” quick clay? Our clay experimental model system: Q-fluorohectorite synthetic clay: Qx-(Mg3-xLix)Si4O10F2, Q is the exchangeable cation (Q = Na+, Li+, Ni2+, Fe3+, etc) ~ 100 nm O ne of our experiments: Orie ntational o rde r in g ravity dispe rse d c lay c o lloids: A sync hrotron x- ray sc atte ring study o f Na- fluo rohe c to rite suspe nsions. E. DiMa si, J.O . Fossum, T. G o g , a nd C . Venkataraman. Phys.Rev. E 64, 061704 (2001) Pure Water NaCl Clay (Fluorohectorite) powder –3 About 3 % in weight About 10 M After Basic ~100nm Liquid clay some particle days of Isotropic gel or glass? ~µm gravity settling 4 ”Phases” in same Sample Tube Nematic like gel or glass? Sediment Se lf- orga niza tion by se dime nta tion c la y pa rtic le s in H2O : Increasing salt: ?? Clay avalanches connected to layered structures or or lubrication layer of house of cards? Snow avalanches and weak layers: All snow exists as layers. Some layers are relatively more cohesive (stronger layers) and others are relatively less cohesive (weaker layers). When the snowpack is stressed by rapid changes (e.g. wind-drifted snow, new snow, or rain) this stress can cause the weak layer to fracture. Liquid Crysta lline Pha se s Cha rac te riza tion O rde r Pa rame te r = O .P. Iso trop ic = Ang ula r d istrib utio n func tio n Phase (O.P. = 0) 2 = S2 = ½<3c o s θ-1> Ne ma tic Pha se (O.P. ≠ 0) Irving Langmuir (Nobel Prize in Chemistry 1932): 1st experimental work in 1938 on liquid crystal structures in a clay suspension. J. Che m Phys. 6, 873 (1938) The most common and most used synthetic clay: Laponite Colloidal gels: Clay goes patchy, Observation of empty liquids and equilibrium gels in a colloidal clay, W. K. Kegel & H. N. W. Lekkerkerker, B. Ruzicka, E. Zaccarelli, L. Zulian, R. Angelini, M. Sztucki, A. Moussaïd, Nature Materials 10, 5–6 (2011) T. Narayanan and F. Sciortino, Nature Materials 10, 56-60 (2011) DLVO Theory: vdW + Screened Electrostatic Rep. FIG. 1. Schematic figures representing repulsive ‘‘Wigner’’ colloidal glass (a), attractive glass (b), and gel (c). Each thick line represents a Laponite disk, while a white ellipsoid represents the range of electrostatic repulsions: (a), long- range electrostatic repulsions dominate. (b), attractive interactions affect the spatial distribution but repulsive interactions still play the predominant role in the slow dynamics of the system. (c), attractive interactions play a dominant role; a percolated network forms, which gives the system its elasticity and higher yield stress. One sample for each point Our clay experimental model system: Q-fluorohectorite synthetic clay: Qx-(Mg3-xLix)Si4O10F2, Q is the exchangeable cation (Q = Na+, Li+, Ni2+, Fe3+, etc) ~ 100 nm Increasing salt: ”Repulsive nematic” ”Attractive nematic” ”Wigner glass” ”Gel” Particles push each other out Particles ”catch each other” in towards container walls, DLVO local minima nematic «small» domains at high enough concentration «large» domains The phase diagram of polydisperse Na-Fluorohectorite–water suspensions: A synchrotron SAXS study, D. M. Fonseca, Y. Meheust, J. O. Fossum, K. D. Knudsen, and K. P. S. Parmar, Phys.Rev. E 79, 021402 (2009) Obtained by combining: Transitions of interest: •Eccentricity of SAXS scattering •Angle of tilt of SAXS scattering •X-ray transmission NS Orde r Parame te r = O.P. = Ang ula r d istributio n func tio n DLVO theory: vdW + Screened electrostatic rep. 2 (i.e The clay particles are effectively soft) = S2 = ½<3c o s θ-1> Cartoon of nematic phase of clay platelets seen from above: Wall anchoring Cartoon of nematic phase of clay platelets, side-view: O rde r Pa rame te r = O .P. = Ang ula r d istrib utio n func tio n 2 = S2 = ½<3c o s θ-1> a and b are ”typical” nematic defect signatures: Disclinations ("discontinuity" in the "inclination" of the director) Ne matic te xtures in c o lloidal dispe rsions o f Na- fluo rohe c to rite sy nthe tic c lay . N.I. Ring d a l, D.M. Fonse c a , E.L. Ha nse n, H. He mme n, and J.O. Fossum. Phys.Rev. E 81, 041702 (2010) Anchoring to Nematic-Isotropic Interface: The Iso tropic - Ne matic Inte rfac e in Suspe nsions o f Na- Fluo rohe c to rite Synthe tic Clay . H. He mme n, N. I. Ring d a l, E. N. De Aze ve d o , M. Eng e lsb e rg , E. L. Ha nse n, Y. Me he ust, J. O . Fossum a nd K. D. Knud se n. Lang muir 25, 12507–12515 (2009) Response to magnetic field: Magnetic field guided se lf- orga niza tion: Glass wall anchoring confirmed by spatially resolved MRI measurements of anisotropic → Isotropic self-diffusion coefficient of water in the g nematic phase. Nematic Magnetic field induced ordering, due to diamagnetic anisotropy of the platelets at Sediment fields above about 1 Tesla. S ~ +0,5 S2 ~ -0.3 2 Anisotropic water diffusion in nematic self assemblies of clay nano-platelets suspended in water.