Freeze-thaw cycles aggravated the negative effects of moss-biocrusts on hydraulic conductivity in sandy land

CATENA ◽  
2021 ◽  
Vol 207 ◽  
pp. 105638
Author(s):  
Yu-Bin Wang ◽  
Ze Huang ◽  
Jia-Xin Qian ◽  
Tong Li ◽  
Jia Luo ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Sandy Land ◽  
Negative Effects ◽  
Freeze Thaw

scholarly journals Mechanical Properties, Permeability, and Freeze–Thaw Resistance of Pervious Concrete Modified by Waste Crumb Rubbers

2018 ◽  
Vol 8 (10) ◽  
pp. 1843 ◽  
Author(s):  
Hanbing Liu ◽  
Guobao Luo ◽  
Yafeng Gong ◽  
Haibin Wei
Keyword(s):  
Mechanical Properties ◽  
Urban Areas ◽  
Rubber Particle ◽  
Crumb Rubber ◽  
Pervious Concrete ◽  
Negative Effects ◽  
Freeze Thaw ◽  
Urban Heat ◽  
Island Phenomena ◽  
Pavement Material

Due to the negative effects that derive from large impervious surfaces in urban areas, pervious concrete has been developed, and has become an environmentally friendly pavement material. As a porous and permeable material, pervious concrete presents an overwhelming advantage in solving urban problems, such as flooding, groundwater decline, urban heat island phenomena, etc. Waste crumb rubber has been verified as a feasible modifier for pavement material. The objective of this paper is to explore the effects of rubber particle size and incorporation level on the permeability, mechanical properties, and freeze–thaw resistance of pervious concrete. Two kinds of rubbers (fine and coarse) with four incorporation levels (2%, 4%, 6%, and 8%) are used in the experiment. Permeability, compressive strength, flexural strength, flexural strain, and freeze–thaw resistance are tested. The results indicate that the addition of rubber slightly decreases strength and permeability, but significantly enhances ductility and freeze-thaw resistance. Fine crumb rubber with a suitable incorporation level could remarkably improve the ductility and freeze–thaw resistance of pervious concrete without sacrificing excessively strength and permeability.

Substrate freeze–thaw in a drained Alberta fen

1989 ◽  
Vol 19 (8) ◽  
pp. 1024-1029 ◽  
Author(s):  
L. E. Swanson ◽  
R. L. Rothwell
Keyword(s):  
Hydraulic Conductivity ◽  
Significant Delay ◽  
Freeze Thaw ◽  
Sample Points ◽  
Surface Peat

The study of ground frost levels in a drained and undrained forested fen showed a significant delay in thaw as well as lower temperatures at 40 and 60 cm depths in the drained area because of the insulating effect of drier surface peat in the drained area. The undrained area froze to greater depths than the drained area, but thawed more rapidly. Ice was present year-round at 16.7% of the sample points in the portion of the drained area of low hydraulic conductivity. Thickness of the frozen layer appeared to be related to hydraulic conductivity as well as drainage. Thawing from underneath the frozen layer accounted for 38% of total thaw in the undrained area.

THE EFFECTS OF SLOPE POSITION AND CROPPING SEQUENCE ON SOIL PHYSICAL PROPERTIES IN PRINCE EDWARD ISLAND

1988 ◽  
Vol 68 (4) ◽  
pp. 763-774 ◽  
Author(s):  
LINNELL M. EDWARDS
Keyword(s):  
Shear Strength ◽  
Hydraulic Conductivity ◽  
Prince Edward Island ◽  
Soil Depth ◽  
Aggregate Stability ◽  
Penetration Resistance ◽  
Slope Position ◽  
Bottom Slope ◽  
Freezing And Thawing ◽  
Freeze Thaw

Soil physical characteristics were examined at depth intervals of 0–15 and 15–30 cm over three slope positions (top-, mid-, and bottom-slope) for three cropping sequences (hay-barley, cereals-barley, and potato-barley). Hydraulic conductivity was a significant (P ≤ 0.05) 40–50% greater at top-slope than mid- or bottom-slope, and aggregate stability percentage was a significant 6–7% greater at bottom-slope than mid- or top-slope when the soil aggregates were pretreated by freezing and thawing (freeze/thaw). Under the potato-barley sequence shear strength, penetration resistance and bulk density were significantly greater than any other sequence by up to 29, 21 and 15%, respectively; while hydraulic conductivity and maximum penetration depth were, respectively, up to 65 and 28% lower than any other sequences. Under hay-barley, hydraulic conductivity and aggregate stability (freeze/thaw) were, respectively, up to a significant 82 and 10% greater than any other sequence. There was, therefore, significantly more compaction under potato-barley and more soil physical enhancement under hay-barley than other respective sequences. Disease severity was up to 55% greater at bottom-slope than at mid-slope or top-slope for Birka barley, which also showed a significant linear decrease (r2 = 0.89) in yield with increasing shear strength. Yield of Perth barley showed a significant linear increase with increasing soil depth (r2 = 0.92) and clay-silt content (r2 = 0.78). Key words: Aggregate stability (freeze/thaw), crop rotation, penetration resistance, shear strength, barley, potatoes, hay

Freeze–thaw cycling concurrent with cation exchange and the hydraulic conductivity of geosynthetic clay liners

2014 ◽  
Vol 51 (6) ◽  
pp. 591-598 ◽  
Author(s):  
Gregory P. Makusa ◽  
Sabrina L. Bradshaw ◽  
Erin Berns ◽  
Craig H. Benson ◽  
Sven Knutsson
Keyword(s):  
Hydraulic Conductivity ◽  
Cation Exchange ◽  
Pore Water ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Chemical Changes ◽  
Clay Liner ◽  
Freeze Thaw ◽  
Exchange Complex ◽  
Before And After

A study was conducted to assess the effect of cation exchange concurrent with freeze–thaw cycling on the hydraulic conductivity of a geosynthetic clay liner (GCL). GCLs were prehydrated by contact with silica flour moistened with synthetic subgrade pore water and subsequently permeated with a solution representing the pore water in the cover soil over a tailings facility. Control tests were conducted using the same procedure, except deionized (DI) water was used as the permeant liquid to preclude cation exchange from the permeant liquid. The GCLs were subjected to 1, 3, 5, 15, and 20 freeze–thaw cycles, and the hydraulic conductivity and exchange complex were determined before and after freeze–thaw cycling to assess chemical changes that occurred during freezing, thawing, and permeation. GCLs undergoing freeze–thaw cycling experienced little to no cation exchange through 5 freeze–thaw cycles. After 20 freeze–thaw cycles, 50% of the sodium (Na+) initially in the exchange complex was replaced by calcium (Ca2+). Dissolution of calcite within the bentonite is a likely source of the Ca2+. Hydraulic conductivity of the GCLs exposed to freeze–thaw cycling was lower than the hydraulic conductivity of a new GCL permeated with DI water (<2.2 × 10−11 m/s). A small increase in hydraulic conductivity (∼2.3 times), which may have been caused by cation exchange, occurred between 15 and 20 freeze–thaw cycles, but the hydraulic conductivity remained below the hydraulic conductivity of a new GCL unexposed to freeze–thaw cycling and permeated with DI water.

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