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Abstract. New systematic experiments reveal that the flexural strength of saline S2 columnar-grained ice loaded normal to the columns can be increased upon cyclic loading by about a factor of 1.5. The experiments were conducted using reversed cyclic loading over ranges of frequencies from 0.1 to 0.6 Hz and at a temperature of −10 ∘C on saline ice of two salinities: 3.0 ± 0.9 and 5.9 ± 0.6 ‰. Acoustic emission hit rate during cycling increases with an increase in stress amplitude of cycling. Flexural strength of saline ice of 3.0 ± 0.9 ‰ salinity appears to increase linearly with increasing stress amplitude, similar to the behavior of laboratory-grown freshwater ice (Murdza et al., 2020b) and to the behavior of lake ice (Murdza et al., 2021). The flexural strength of saline ice of 5.9 ± 0.6 ‰ depends on the vertical location of the sample within the thickness of an ice puck; i.e., the strength of the upper layers, which have a lower brine content, was found to be as high as 3 times that of lower layers. The fatigue life of saline ice is erratic. Cyclic strengthening is attributed to the development of an internal back stress that opposes the applied stress and possibly originates from dislocation pileups.
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The flexural strength of bonded ice
Abstract. The flexural strength of ice surfaces bonded by freezing, termedfreeze bond, was studied by performing four-point bending tests of bondedfreshwater S2 columnar-grained ice samples in the laboratory. The sampleswere prepared by milling the surfaces of two ice pieces, wetting two of thesurfaces with water of varying salinity, bringing these surfaces together,and then letting them freeze under a compressive stress of about 4 kPa. Thesalinity of the water used for wetting the surfaces to generate the bondvaried from 0 to 35 ppt (parts per thousand). Freezing occurred in air under temperatures varyingfrom −25 to −3 ∘C over periods that varied from 0.5 to∼ 100 h. Results show that an increase in bond salinity ortemperature leads to a decrease in bond strength. The trend for the bondstrength as a function of salinity is similar to that presented in Timco andO'Brien (1994) for saline ice. No freezing occurs at −3 ∘C oncethe salinity of the water used to generate the bond exceeds ∼ 25 ppt. The strength of the saline ice bonds levels off (i.e., saturates)within 6–12 h of freezing; bonds formed from freshwater reach strengthsthat are comparable or higher than that of the parent material in less than0.5 h.
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- Award ID(s):
- 1947107
- PAR ID:
- 10494407
- Publisher / Repository:
- Copernicus
- Date Published:
- Journal Name:
- The Cryosphere
- Volume:
- 15
- Issue:
- 6
- ISSN:
- 1994-0424
- Page Range / eLocation ID:
- 2957 to 2967
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.5194/tc-15-2957-2021
