The Tensile Strength of Compacted Clays as Affected by Suction and Soil Structure

2007 ◽  
pp. 219-226 ◽  
Author(s):  
Rainer M. Zeh ◽  
Karl Josef Witt
Keyword(s):  
Tensile Strength ◽  
Soil Structure ◽  
Compacted Clays

scholarly journals Tensile and erosive strength of soil macro-aggregates from soils under different management system

2014 ◽  
Vol 62 (4) ◽  
pp. 324-333 ◽  
Author(s):  
Emilia Urbanek ◽  
Rainer Horn ◽  
Alwin J.M. Smucker
Keyword(s):  
Tensile Strength ◽  
Organic Carbon ◽  
Soil Structure ◽  
Soil Aggregates ◽  
Soil Health ◽  
Soil Tillage ◽  
Structure Stability ◽  
Total Strength ◽  
Tillage Practices ◽  
Aggregate Strength

Abstract Reduced soil tillage practices are claimed to improve soil health, fertility and productivity through improved soil structure and higher soil organic matter contents. This study compares soil structure stability of soil aggregates under three different tillage practices: conventional, reduced and no tillage. The erosive strength of soil aggregates has been determined using the abrasion technique with the soil aggregate erosion chambers (SAE). During abrasion soil aggregates have been separated into the exterior, transitional and interior regions. The forces needed to remove the material from the aggregate were calculated as erosive strength and compared with the tensile strength of the aggregates derived from crushing tests. The relationship between aggregate strength and other soil properties such as organic carbon and hydrophobic groups’ content has also been identified. The results show that erosive and tensile strength of soil aggregates is very low in topsoil under conventional and reduced tillage comparing with the subsoil horizons. Negative correlation was found between the content of organic carbon, hydrophobic compounds and erosive aggregate strength which suggests that the stabilising effect of soils organic carbon may be lost with drying. The positive relationship between the tensile strength and erosive strength for aggregates of 8-5 mm size suggests that the total strength of these aggregates is controlled by the sum of strength of all concentric layers

Generation of microcracks in molded soils by rapid wetting

Soil Research ◽  
1989 ◽  
Vol 27 (1) ◽  
pp. 169 ◽  
Author(s):  
CD Grant ◽  
AR Dexter
Keyword(s):  
Water Management ◽  
Tensile Strength ◽  
Natural Regeneration ◽  
Soil Structure ◽  
Initial Water ◽  
Fracture Surfaces ◽  
Water Contents ◽  
Wetting Rate ◽  
Soil Tensile Strength

Tillage of compacted or of puddled and remoulded soils is a major agronomic problem internationally. The natural regeneration of microcracks (tilth mellowing) prior to the cultivation of such soils can reduce the energy needed to work them. Rapid wetting, under certain conditions, plays a major role in developing cracks in structurally damaged soils. This study reports the use of different initial water contents and wetting rates to examine the development of 'new' soil structure, described mechanically by tensile strength, and optically by measurements of the relief of fractured soil surfaces. New terminology is introduced to describe the rate of wetting needed to induce mellowing and to describe the rugosity of soil fracture surfaces. Rapid wetting was found to induce microcracking in soils, even with initial matric potentials as wet as -1.0 to -1.5 MPa. Implications for water management are briefly considered. Visual and analytical evidence from photographs and computer images indicates that internal microcracking is almost always detectable whenever the wetting rate is sufficiently high to reduce the soil tensile strength.

scholarly journals Tensile strength, friability and organic carbon in an oxisol under a crop-livestock system

2009 ◽  
Vol 66 (4) ◽  
pp. 499-505 ◽  
Author(s):  
Rachel Muylaert Locks Guimarães ◽  
Cássio Antonio Tormena ◽  
Sérgio José Alves ◽  
Jonez Fidalski ◽  
Éverton Blainski
Keyword(s):  
Tensile Strength ◽  
Organic Carbon ◽  
Soil Compaction ◽  
Soil Structure ◽  
Soil Depth ◽  
Limiting Factor ◽  
Surface Layers ◽  
Livestock Systems ◽  
Livestock System ◽  
Soil Tensile Strength

The crop-livestock system can promote soil compaction in surface layers, mainly due to animal trampling. However, plants and their root growth, in interaction with animal trampling, can decrease the deleterious changes in soil structure caused by this system. Up to the present time, the physical soil modifications in crop-livestock systems, including oat and ryegrass crops for winter animal forages are unknown. The objective of this study was to quantify and to relate tensile strength, friability and soil organic carbon in an Oxisol under a crop-livestock system. The study was conducted in Campo Mourão - Paraná, Brazil. Four forage heights were used for the winter forages: 7, 14, 21 and 28 cm. For each forage height, five soil blocks were randomly collected from each layer of 0 - 0.1, 0.1 - 0.2 and 0.2 - 0.3 m of depth. The increase in carbon content promotes an increase in soil tensile strength at the 0.1 - 0.2 m soil depth, this layer having the highest values for tensile strength. The forage height of 21 cm was found to be the best height for soil friability, and the soil was very friable at this height. Despite a decrease in friability in the upper layers of the soil, the crop-livestock system was not found to be a limiting factor for the subsequent cultivation of annual crops.

Tensile Strength of Compacted Clays during Desiccation under Elevated Temperatures

2021 ◽  
Vol 44 (4) ◽  
pp. 20200114 ◽  
Author(s):  
Kwestan Salimi ◽  
Amy B. Cerato ◽  
Farshid Vahedifard ◽  
Gerald A. Miller
Keyword(s):  
Tensile Strength ◽  
Elevated Temperatures ◽  
Compacted Clays

Biochar impact on tensile strength of Dystric Cambisol aggregates – a model study

2020 ◽  
Author(s):  
Katarzyna Szewczuk-Karpisz ◽  
Agnieszka Tomczyk ◽  
Zofia Sokołowska ◽  
Marcin Turski ◽  
Marta Cybulak ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Soil Structure ◽  
Mechanical Stability ◽  
Soil Aggregates ◽  
Soil Condition ◽  
Crop Productivity ◽  
Gas Diffusion ◽  
Water Infiltration ◽  
Satellite Monitoring ◽  
Root Penetration

<p>Aggregate tensile strength is a significant parameter of soil structure. Adequate mechanical stability of aggregates promotes long-term crop productivity due to, inter alia, maintaining gas diffusion, facilitating root penetration and improving water infiltration. Soil aggregates characterized by high tensile strength are also resistant to erosion. Nowadays, intensive agriculture and environmental pollution contribute to clear deterioration of soil condition. The soil structure is often destroyed. In order to limit the negative phenomena, various soil additives are used, e.g. biochar.</p><p>In this paper, the effect of wood waste biochar on tensile strength and porosity of Dystric Cambisol artificial aggregates was examined. The experiments were performed on dry-air and wet soil aggregates non-containing and containing 0.1% or 5% dose of biochar. Tensile strength of the probes was determined using strength testing device (Zwick/Roell), whereas porosity – by mercury intrusion porosimetry (Micrometrics). The obtained results indicated that the biochar addition decreases tensile strength of all examined aggregates. This effect was more significant for higher biochar dose – 5%. This phenomenon is probably connected with formation of macropores of larger sizes within aggregates after the biochar addition.</p><p>Research was conducted under the project "Water in soil - satellite monitoring and improving the retention using biochar" no. BIOSTRATEG3/345940/7/NCBR/2017 which was financed by Polish National Centre for Research and Development in the framework of "Environment, agriculture and forestry" - BIOSTRATEG strategic R&D programme.</p>

Phase Transformations in Ti-7w/oMo-3w/oMe Alloy

1974 ◽  
Vol 32 ◽  
pp. 514-515
Author(s):  
S. Fujishiro
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Transmission Electron Microscopy ◽  
Tensile Strength ◽  
Mechanical Processing ◽  
Ray Method ◽  
X Ray ◽  
Transmission Electron ◽  
Water Quench ◽  
Alpha Beta

The mechanical properties of three titanium alloys (Ti-7Mo-3Al, Ti-7Mo- 3Cu and Ti-7Mo-3Ta) were evaluated as function of: 1) Solutionizing in the beta field and aging, 2) Thermal Mechanical Processing in the beta field and aging, 3) Solutionizing in the alpha + beta field and aging. The samples were isothermally aged in the temperature range 300° to 700*C for 4 to 24 hours, followed by a water quench. Transmission electron microscopy and X-ray method were used to identify the phase formed. All three alloys solutionized at 1050°C (beta field) transformed to martensitic alpha (alpha prime) upon being water quenched. Despite this heavily strained alpha prime, which is characterized by microtwins the tensile strength of the as-quenched alloys is relatively low and the elongation is as high as 30%.

A TEM microscopical investigation of the magnetic domain structure of a metastable austenitic stainless steel

1994 ◽  
Vol 52 ◽  
pp. 696-697
Author(s):  
G. Fourlaris ◽  
T. Gladman
Keyword(s):  
Tensile Strength ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Cold Rolling ◽  
Solution Treatment ◽  
Magnetic Domain ◽  
High Strength ◽  
Medium Carbon Steel ◽  
Magnetic Characteristics ◽  
Metastable Austenitic Stainless Steel

Stainless steels have widespread applications due to their good corrosion resistance, but for certain types of large naval constructions, other requirements are imposed such as high strength and toughness , and modified magnetic characteristics.The magnetic characteristics of a 302 type metastable austenitic stainless steel has been assessed after various cold rolling treatments designed to increase strength by strain inducement of martensite. A grade 817M40 low alloy medium carbon steel was used as a reference material.The metastable austenitic stainless steel after solution treatment possesses a fully austenitic microstructure. However its tensile strength , in the solution treated condition , is low.Cold rolling results in the strain induced transformation to α’- martensite in austenitic matrix and enhances the tensile strength. However , α’-martensite is ferromagnetic , and its introduction to an otherwise fully paramagnetic matrix alters the magnetic response of the material. An example of the mixed martensitic-retained austenitic microstructure obtained after the cold rolling experiment is provided in the SEM micrograph of Figure 1.

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