226
A. V. Panko et al.
close to 2.5 nm. According stoichiometric conceptions this witnesses that minimal
nanoparticle sizes approach 4 nm. It is quite possible that they are connected
with phase contacts too, as already indicated for Kuyalnik peloid (Fig. 13.10b).
Physicomechanical properties of IOHSS and PS are most influenced by moisture
mass fraction in their composition. Thus, comparatively low-concentrated Black Sea
peloid suspensions (35% and 23% of solid phase) are characterized by thixotropic
flow mode of those suspensions (Fig. 13.4). Abnormal rheopectic flow mode for
Kuyalnik peloid is observed at solid phase mass fraction of 45% (Fig. 13.5), and,
as already mentioned, it is explained by strong phase nanocontacts in aggregates of
colloid particles (Fig. 13.10b). The Azov Sea pelagic sediment suspensions at 23%
moisture mass fraction have thixotropic flow mode, similar to low-concentrated
Black Sea peloid (Fig. 13.4b). At the same time, flow curves for concentrated
suspensions of bentonite clay (Fig. 13.7), glauconite (Fig. 13.8), and hydromica
(Fig. 13.9) have abnormal character. The same character was also detected for
concentrated suspension of IOHSS from marine PS, where its composition had 16%
of clay components and 84% of goethite [28]. All four specimens had concentrations
close to Atterberg plasticity limit, which separates plastic state from conditionally
solid (semisolid) state. Such results need additional description using conceptions
of classic mechanics.
Figure 13.11 shows material theoretical load and unload curves typical for elastoviscous state of tested material. At loading of a specimen (OCA curve segment)
solid material elastic state turns into viscous (OA curve segment). At unloading
(on AD segment), plastic sample properties are disappearing and elasticity usual
for solid (semisolid) material is being back at condition of irreversible process
(point B). At further specimen loading (dashed-line curve BA’) its plastic properties
appear at ££’ segment and disappear at A’D’ segment. Estimated view of viscosity
curve for plastic flow at CAD segment (Fig. 13.11, curves 1 and b) shows that
specimen viscosity change at loading is described by curve 1 at lower shear
stress values than for unloading (curve 2). Those curves (1 and 2) compared with
respective abnormal rheological curves on Figs. 13.7, 13.8, and 13.9, and in [28],
shows first of all that curves have similar curve trend as a result of identical
structures’ plastic flow mechanism. The latter is based upon effect of system
transition from solid-like to plastic state in conditions of phase contacts formation
[27]. Interaction of micro- and colloid particles in phase contacts according to
Rebinder is conditioned by short-range forces of cohesion or adhesion. The latter
ones are realized on surface much bigger than the surface of elemental lattice.
Adhesion of solid-like structures in such conditions is formed from not less than
10 2 –10 3 of atomic bonds, i.e., on nanolevel or on colloid level with formation of
structural–mechanical barrier according to Rebinder. Such bonds can be seen in
Fig. 13.10, formed with nanoparticle participation. As distinct from coagulation
ones such bonds are dissociated irreversibly, and it can be seen on experimental
curves in Figs. 13.7, 13.8, and 13.9 and theoretical curves in Fig. 13.11. Thus, it
can be considered as proven that abnormal rheological curve trend for concentrated
suspensions of clay minerals, IOHSS, PS, and peloids is conditioned by irreversible
dissociation of phase solid-like contacts built from nanoparticle blocks of silicates,
A. V. Panko et al.
close to 2.5 nm. According stoichiometric conceptions this witnesses that minimal
nanoparticle sizes approach 4 nm. It is quite possible that they are connected
with phase contacts too, as already indicated for Kuyalnik peloid (Fig. 13.10b).
Physicomechanical properties of IOHSS and PS are most influenced by moisture
mass fraction in their composition. Thus, comparatively low-concentrated Black Sea
peloid suspensions (35% and 23% of solid phase) are characterized by thixotropic
flow mode of those suspensions (Fig. 13.4). Abnormal rheopectic flow mode for
Kuyalnik peloid is observed at solid phase mass fraction of 45% (Fig. 13.5), and,
as already mentioned, it is explained by strong phase nanocontacts in aggregates of
colloid particles (Fig. 13.10b). The Azov Sea pelagic sediment suspensions at 23%
moisture mass fraction have thixotropic flow mode, similar to low-concentrated
Black Sea peloid (Fig. 13.4b). At the same time, flow curves for concentrated
suspensions of bentonite clay (Fig. 13.7), glauconite (Fig. 13.8), and hydromica
(Fig. 13.9) have abnormal character. The same character was also detected for
concentrated suspension of IOHSS from marine PS, where its composition had 16%
of clay components and 84% of goethite [28]. All four specimens had concentrations
close to Atterberg plasticity limit, which separates plastic state from conditionally
solid (semisolid) state. Such results need additional description using conceptions
of classic mechanics.
Figure 13.11 shows material theoretical load and unload curves typical for elastoviscous state of tested material. At loading of a specimen (OCA curve segment)
solid material elastic state turns into viscous (OA curve segment). At unloading
(on AD segment), plastic sample properties are disappearing and elasticity usual
for solid (semisolid) material is being back at condition of irreversible process
(point B). At further specimen loading (dashed-line curve BA’) its plastic properties
appear at ££’ segment and disappear at A’D’ segment. Estimated view of viscosity
curve for plastic flow at CAD segment (Fig. 13.11, curves 1 and b) shows that
specimen viscosity change at loading is described by curve 1 at lower shear
stress values than for unloading (curve 2). Those curves (1 and 2) compared with
respective abnormal rheological curves on Figs. 13.7, 13.8, and 13.9, and in [28],
shows first of all that curves have similar curve trend as a result of identical
structures’ plastic flow mechanism. The latter is based upon effect of system
transition from solid-like to plastic state in conditions of phase contacts formation
[27]. Interaction of micro- and colloid particles in phase contacts according to
Rebinder is conditioned by short-range forces of cohesion or adhesion. The latter
ones are realized on surface much bigger than the surface of elemental lattice.
Adhesion of solid-like structures in such conditions is formed from not less than
10 2 –10 3 of atomic bonds, i.e., on nanolevel or on colloid level with formation of
structural–mechanical barrier according to Rebinder. Such bonds can be seen in
Fig. 13.10, formed with nanoparticle participation. As distinct from coagulation
ones such bonds are dissociated irreversibly, and it can be seen on experimental
curves in Figs. 13.7, 13.8, and 13.9 and theoretical curves in Fig. 13.11. Thus, it
can be considered as proven that abnormal rheological curve trend for concentrated
suspensions of clay minerals, IOHSS, PS, and peloids is conditioned by irreversible
dissociation of phase solid-like contacts built from nanoparticle blocks of silicates,