Rapid freezing of saturated clays under large thermal gradients

2021 ◽  
Vol 11 (4) ◽  
pp. 1-16
Author(s):  
Jungyeon Jang ◽  
Minsu Cha
Keyword(s):  
Freezing Behavior ◽  
Rapid Freezing ◽  
Thermal Gradients ◽  
Micro Ct ◽  
Water Migration ◽  
Volume Changes ◽  
Fine Grained ◽  
Insufficient Time ◽  
Lens Formation ◽  
Inner Parts

This study investigates the rapid freezing behavior of saturated clays under large thermal gradients. Although the freezing characteristics of soils under natural/low thermal gradients such as ice lens formation and water migration have been extensively studied, the freezing of a saturated soil under a large thermal gradient is not understood. This study presents rapid freezing tests to examine the freezing behavior of saturated fine-grained soils in a closed system under large thermal gradients using liquid nitrogen (LN). Temperatures are measured inside specimens during freezing and micro-CT visualized internally after freezing. Results show that large thermal gradients develop near the surfaces of specimens upon their submersion in LN. The specimens freeze homogeneously, and no visible ice lenses form, owing to the insufficient time for water migration and ice segregation under rapid freezing. The specimens fracture and split into major pieces, under no confining stresses in this study; freezing first occurs near the boundaries, and the freezing front propagates inward, creating temporal, differential volume changes between the outer and inner parts of the specimens, which leads to fractures in the unconfined state. The fractures affect subsequent temperature propagation and thermal gradients.

A mechanistic theory of ice lens formation in fine-grained soils

1980 ◽  
Vol 17 (4) ◽  
pp. 473-486 ◽  
Author(s):  
Jean-Marie Konrad ◽  
Norbert R. Morgenstern
Keyword(s):  
Steady State ◽  
Heat Flow ◽  
Freezing Temperature ◽  
Cold Side ◽  
Freezing Soil ◽  
Fine Grained ◽  
Mechanistic Theory ◽  
Two Parameters ◽  
Lens Formation

This study reveals that a freezing soil can be characterized by two parameters, the segregation-freezing temperature Ts and the overall permeability of the frozen fringe [Formula: see text]. During unsteady heat flow, the variation of these parameters with temperature produces rhythmic ice banding in fine-grained soils. At the onset of steady-state conditions, freezing tests conducted at a fixed warm end temperature showed that Ts was independent of the cold side step temperature. In addition, a model is presented that indicates how the overall permeability of the frozen fringe can be calculated without detailed measurements at the scale of the frozen fringe. It is also constant in the tests reported here.

Permeability and volume changes in till due to cyclic freeze/thaw

1998 ◽  
Vol 35 (3) ◽  
pp. 471-477 ◽  
Author(s):  
Peter Viklander
Keyword(s):  
Soil Structure ◽  
Void Ratio ◽  
Vertical Direction ◽  
Rigid Wall ◽  
Freezing And Thawing ◽  
Volume Changes ◽  
Freeze Thaw ◽  
Fine Grained ◽  
Loose Soil ◽  
Freezing And Thawing Cycles

A fine-grained nonplastic till was compacted in the laboratory in three types of rigid wall permeameters, having a volume of 0.4, 1.5, and 25 dm3, respectively, and, was thereafter exposed to a maximum of 18 freezing and thawing cycles. The permeabilities in the vertical direction of saturated samples were measured in unfrozen soil as well as in thawed soil. The results show that the permeabilities changed after freezing and thawing. The magnitude of the changes in this study were in the range 0.02-10 times after freeze/thaw compared with the unfrozen soil. Soil exhibited volume changes subsequent to freeze/thaw. The volume typically decreased for an initially loose soil and increased for a dense soil. Independent of whether the initial soil structure was loose or dense, a constant "residual" void ratio, eres, was obtained after 1-3 cycles. For the soil investigated, the residual void ratio ranged from 0.31 to 0.40.Key words: till, fine-grained, non plastic, permeability, freeze/thaw, residual void ratio.

Effects of cyclic freezing and thawing on volume changes and permeabilities of soft fine-gained soils

1996 ◽  
Vol 33 (4) ◽  
pp. 529-537 ◽  
Author(s):  
K D Eigenbrod
Keyword(s):  
Moisture Content ◽  
Initial Moisture Content ◽  
Maximum Volume ◽  
Freezing And Thawing ◽  
Volume Changes ◽  
One Dimensional ◽  
Freeze Thaw ◽  
Fine Grained ◽  
Liquidity Index ◽  
Thaw Consolidation

Soft, fine-grained soils were exposed to cyclic one-dimensional, open-system freezing and thawing, resulting in maximum volume changes of up to 30%, depending on the initial moisture content and plasticity of the clay as well as on the rate of freezing. A linear relationship between the net volume changes subsequent to freezing and thawing and the liquidity index prior to freezing and thawing was obtained. This correlation is not unique, but depends on rate and mode of freezing. Thus, settlements from freeze–thaw consolidation in the field can be predicted from such tests if the rate and mode of freezing are the same as in the field. During cyclic freezing and thawing the soils became fissured and jointed, resulting for most clays in large increases in their bulk permeabilities, which increased with an increasing number of freeze–thaw cycles, often by more than two orders of magnitude. For some materials, however, little change in permeability occured. Key words: cyclic freeze–thaw, clays, freeze–thaw consolidation, permeability, volume changes.

scholarly journals Estimation of pulmonary arterial volume changes in the normal and hypertensive fawn-hooded rat from 3D micro-CT data

2002 ◽  
Author(s):  
Robert C. Molthen ◽  
Christian Wietholt ◽  
Steven T. Haworth ◽  
Christopher A. Dawson
Keyword(s):  
Micro Ct ◽  
Volume Changes ◽  
Pulmonary Arterial ◽  
Ct Data

Study of Residual Stresses in Traditional Ceramics

2014 ◽  
Vol 608 ◽  
pp. 14-20
Author(s):  
C. Venturelli ◽  
Mariano Paganelli
Keyword(s):  
Residual Stresses ◽  
Ceramic Ware ◽  
Thermal Gradients ◽  
Volume Changes ◽  
Lower Face ◽  
Coupling Factors ◽  
The Common ◽  
Porcelain Tiles ◽  
Traditional Ceramics ◽  
Porcelain Tile

Residual stresses in traditional ceramics may have different origin and nature. In glazed tiles (both porous and sintered), they can be due to the thermal expansion mismatch of glaze and body. Another type of residual stresses in glazed and unglazed porcelain tiles is due to temperature gradients during cooling, which give rise to volume variations in different areas of the same ceramic ware. Thermal gradients may originate not only between the surface and the core of the tile, but also between the upper and the lower face of the tile. The common practice in the porcelain tile industry to use differential cooling to control the planarity of the finished product induces permanent changes of volume in different areas of the ceramic ware, which give rise to permanent states of stress. At room temperature there are two main stress relaxation mechanisms, depending on the nature of the tiles: cracks growth in porcelain tiles and post-expansion in porous tiles. Generally, residual stresses relaxation cause delayed curvature according to these different mechanisms. Optical dilatometry and optical fleximetry techniques allow to investigate the volume changes induced by the cooling rate and the glaze-body coupling, factors responsible for residual stresses.

The ultrabasic lava flows of Mashhad, North East Iran

1981 ◽  
Vol 118 (1) ◽  
pp. 49-58 ◽  
Author(s):  
B. Majidi
Keyword(s):  
Lava Flows ◽  
Small Scale ◽  
Lower Carboniferous ◽  
Transition Zones ◽  
Fine Grained ◽  
North East ◽  
Flow Units ◽  
Small Crystals ◽  
Inner Parts ◽  
Ne Iran

SummaryUltrabasic and basic lavas are interbedded with metamorphosed Lower-Carboniferous sediments in the northern slope of the Alborz mountains, NE Iran. In the outcrop area at least 15 individual units of ultrabasic lava have been observed. Flow units range in thickness from a few metres up to about 70 m. The inner parts of the flow units are holo-crystalline, showing a poikilitic texture with rounded small crystals of serpentinized olivine surrounded by large crystals of clinopyroxene (‘wehrlitic facies’). The upper portions of the thicker units are olivine-free, and pyroxene, sometimes accompanied by brown hornblende, is set in a groundmass of fine-grained epidotized plagioclase (‘doleritic facies’). In the upper and lower margins of flows the groundmass is devitrified to chlorite and tremolite. Small-scale differentiation and igneous lamination is observable in transition zones between the wehrlitic and doleritic ‘facies’. The upper doleritic facies and other individual basic units have a tholeitic chemistry. In contrast, the chemical composition of wehrlitic rocks (which predominate amongst the exposed rocks in the area) is comparable with Archaean ultrabasic lava flows in Canada and southern Africa.

Strength behaviour of lime-treated soils in the presence of sulphate

2000 ◽  
Vol 37 (6) ◽  
pp. 1358-1367 ◽  
Author(s):  
P V Sivapullaiah ◽  
A Sridharan ◽  
H N Ramesh
Keyword(s):  
Shear Strength ◽  
Black Cotton Soil ◽  
Strength Development ◽  
Volume Changes ◽  
Treated Soil ◽  
Fine Grained ◽  
Strain Behaviour ◽  
Abnormal Volume ◽  
Stabilized Soil ◽  
Cemented Soils

Lime has been used extensively to improve the shear strength of fine-grained soils. It has been recently reported that the presence of sulphate causes abnormal volume changes in lime-stabilized soil. The paper presents the strength behaviour of lime-treated montmorillonitic natural black cotton soil in the presence of varying sulphate contents after curing for periods of up to 365 days. Alteration of soil–lime reactions in the presence of sulphate affects the strength development by cementation. Consequently, the stress–strain behaviour effective stress paths of soil cured with sulphate are similar to those of normally consolidated soil rather than cemented soils. The reduction in shear strength due to a reduction in effective cohesion intercept occurs for lime-treated soil cured with sulphate for long periods.Key words: clays, cohesion, fabric, friction, shear strength.

scholarly journals Freezing Behavior of Prunus, Subgenus Padus, Flower Buds

1992 ◽  
Vol 117 (6) ◽  
pp. 955-960 ◽  
Author(s):  
Sorkel A. Kader ◽  
Edward L. Proebsting
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Freezing Behavior ◽  
Entire Length ◽  
Prunus Serotina ◽  
Xylem Vessel ◽  
Water Migration ◽  
Flower Buds ◽  
Vessel Elements

Flower buds of Prunus serotina Ehrh. produced high temperature exotherms (HTEs) and low temperature exotherms (LTEs). Supercooling in P. serotina occurred during full dormancy in December and early January but disappeared thereafter, whereas no supercooling was observed in P. padus L. or P. virginiana L. Both intact and detached lnflorescences of P. serotina supercooled and froze as a unit and not as individual florets. Exotherms in dehydrated parts occurred at lower temperatures than in hydrated parts. Dormant buds of P. serotina lost the detectable exotherms when kept at -7C for 2 days, while buds stored at 3C exhibited LTEs between -20 and -26C. Dormant Morescences of P. serotina were filled with elongated procambium and pith cells. In contrast, P. padus and P. virginiana had differentiated xylem vessel elements (XVE) the entire length of the inflorescence and did not supercool. Bud scales and bud axis of P. serotina were the flower parts where water apparently migrated during storage at 3 and -7C. This was not observed for P. padus and P. virginiana flower buds. The rate of water migration from the inflorescences to bud scales and axis probably plays a role in the freezing behavior of P. serotina.

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