Silt fraction effects of frozen soils on frozen water content, strength, and stiffness

Introduction Plaster of Paris (PoP) impregnated bandages have been used to maintain the position of bones and joints for over a century. Classically, wool dressing is applied to the limb before the PoP, which can then be moulded to the desired shape. A modification of this practice is to wrap the PoP bandages circumferentially in cotton before wetting and applying to the patient in an attempt to reduce inhalation of plaster dust and reduce mess. However, this may affect the water content of the cast and therefore also its setting properties and strength. This study compared the setting properties of PoP casts when used with and without cotton wrapping. Methods Sixty specimens, compliant with the American Society for Testing and Materials standards for three-point bending tests, were prepared, with thirty wrapped in cotton. All were weighed before and after water immersion, and wrapped around a plastic cylinder to mimic limb application. Bending stiffness and yield strength was measured on a servohydraulic materials testing machine at 2, 6, 12, 24, 48 and 72 hours. Results The water content of cotton-wrapped plaster was significantly higher (50%) than that of standard plaster. It had significantly lower strength up to 24 hours and significantly lower stiffness up to 72 hours. Conclusions The initial decrease in strength and stiffness of the cast wrapped in cotton may comprise the ability of the backslab to hold the joint or bone in an optimal position. Any modification of the standard plaster slab application technique should allow for the potential adverse effects on the plaster setting properties.

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DRYING OF FROZEN SOILS

Canadian Journal of Soil Science ◽

10.4141/cjss88-079 ◽

1988 ◽

Vol 68 (4) ◽

pp. 807-811 ◽

Cited By ~ 10

Author(s):

E. de JONG ◽

R. G. KACHANOSKI

Keyword(s):

Environmental Factors ◽

Key Words ◽

Water Content ◽

Maximum Rate ◽

Drying Rate ◽

Frozen Soils ◽

Drying Rates

Drying rates of frozen aggregates varied from 2 mg cm−2 h−1 to zero, mainly in response to decreasing water content. Temperature, windspeed and dryness of the air controlled the maximum rate of drying. The variation in drying rate with water content was explained by the balance between ice and water in the pores. Key words: Frozen soils, evaporation, environmental factors

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Compressive strength behavior of fine-grained frozen soils

Canadian Geotechnical Journal ◽

10.1139/t90-062 ◽

1990 ◽

Vol 27 (4) ◽

pp. 472-483 ◽

Cited By ~ 11

Author(s):

Harsha Wijeweera ◽

Ramesh C. Joshi

Keyword(s):

Compressive Strength ◽

Water Content ◽

Yield Stress ◽

Constant Strain Rate ◽

Unit Weight ◽

Total Water Content ◽

Total Water ◽

Frozen Soils ◽

Fine Grained ◽

Dry Unit Weight

Constant strain-rate (0.01/s) uniaxial compression-strength tests were conducted on more than 200 saturated samples of six fine-grained frozen soils at temperatures between −5 and −17 °C. Saturated soil samples containing total water contents between 15% and 105% were prepared using a consolidation apparatus specially designed for this purpose. The effect of dry unit weight, total water content, temperature, and soil type on the behavior of peak compressive strength was studied. Test results indicate the peak compressive strength of fine-grained soils is sensitive to changes in the dry unit weight and the total water content. The temperature dependence of the peak compressive strength is represented by a simple power law. An empirical formula has been developed to predict the peak compressive strength of fine-grained frozen soils at a particular temperature using index properties, specific surface area, particle-size distribution, and dry unit weight. A linear relationship exists between the peak compressive stress and the yield stress. Key words: peak compressive strength, yield stress, frozen soils, fine-grained soils, dry unit weight, failure strain, temperature, total water content, slurry consolidation.

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The measurement of unfrozen water content by time domain reflectometry: results from laboratory tests

Canadian Geotechnical Journal ◽

10.1139/t81-012 ◽

1981 ◽

Vol 18 (1) ◽

pp. 131-144 ◽

Cited By ~ 98

Author(s):

D. E. Patterson ◽

M. W. Smith

Keyword(s):

Dielectric Property ◽

Water Content ◽

Time Domain ◽

Empirical Relationship ◽

Time Domain Reflectometry ◽

Unfrozen Water ◽

Published Data ◽

Frozen Soils ◽

Unfrozen Water Content ◽

Property Versus

A new technique for determining the volumetric unfrozen water content of frozen soils is reported, which uses time domain reflectometry (TDR) to measure the dielectric property. Using precise temperature control, the technique, which was developed previously by others for unfrozen soils, has been successfully applied to the measurement of unfrozen water contents of frozen soils. Curves of the dielectric property versus temperature show a close similarity to unfrozen water content curves, for a variety of soils. Results from experiments on ice–water mixtures and from combined TDR–dilatometry experiments on frozen soils suggest that an empirical relationship obtained by Topp, Davis, and Annan may be applicable to frozen media as well as unfrozen soils. Using this relationship, dielectric values were converted to unfrozen water content values, and the results agreed very closely with published data for similar soils, determined by other methods. For silt loams, agreement is typically within ± 1½% in volumetric water content, and for clays ± 3 %. Some of this difference is undoubtedly due to soil sample variations.

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