Factors determining the optimum moisture content (OMC) of greywacke aggregates from northern New Zealand

2019 ◽  
Vol 19 ◽  
pp. 35-43
Author(s):  
Wentao Li ◽  
Douglas J. Wilson ◽  
Tam J. Larkin ◽  
Philippa M. Black
Keyword(s):  
New Zealand ◽  
Moisture Content ◽  
Optimum Moisture Content

scholarly journals Effect of Sand Percentage on the Compaction Properties and Undrained Shear Strength of Low Plasticity Clay

2021 ◽  
Vol 9 (1) ◽  
pp. 16-20
Author(s):  
Iyad Alkroosh ◽  
Ali Al-Robay ◽  
Prabir Sarker ◽  
Saif Alzabeebee
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Undrained Shear Strength ◽  
Optimum Moisture Content ◽  
Dry Density ◽  
Sand Content ◽  
Compression Tests ◽  
Maximum Dry Density ◽  
Sand Mixture ◽  
Undrained Shear

This paper investigates the influence of sand content on the mechanical behavior of a low plasticity clay that collected from south of Iraq (Sumer town). Samples have been prepared with sand contents of 0%, 10%, 20%, 30%, and 40% of the clay weight. Standard Proctor and unconfined compression tests have been carried out and the optimum moisture content, maximum dry density, and undrained shear strength have been determined. The results show a gradual increasing trend of the maximum dry density with the increase of the sand content up to 30%. The highest dry density reaches 1.90 g/cm3 corresponding to an optimum moisture content of 12%. In addition, this paper shows that the undrained shear strength is inversely proportional to the increase of the percentage of sand. The results of this work provide a useful addition to the literature regarding the behaviour or low plasticity clay-sand mixture.

Utilization of Large-Scale Rolling-Wheel Tester to Investigate the Stress Reduction in Pavement Layers Due to the Use of Geosynthetic Materials

2019 ◽  
Vol 2673 (2) ◽  
pp. 445-455
Author(s):  
Jason Wright ◽  
S. Sonny Kim ◽  
Mi G. Chorzepa ◽  
Stephan A. Durham
Keyword(s):  
Moisture Content ◽  
Large Scale ◽  
Pressure Sensors ◽  
Optimum Moisture Content ◽  
Small Scale ◽  
Wheel Load ◽  
Subgrade Soils ◽  
Rolling Wheel ◽  
Aggregate Base ◽  
Pavement Foundation

In a geosynthetic-reinforced pavement system, the load-bearing capacity of subgrade soil is improved by the lateral distribution of vertical stresses at the reinforcing layer. Under small-scale triaxial testing, the tensile properties of the geosynthetic are difficult to measure. Therefore, it is desirable to conduct large-scale testing to accurately monitor the behavior of geosynthetic-reinforced pavement foundations when subjected to rolling-wheel loadings. This study investigates the behavior of geosynthetic-reinforced pavement foundation systems through large-scale rolling-wheel tests performed with problematic subgrade soils found in north Georgia. Sixteen large-scale specimens were constructed of which twelve were reinforced with geosynthetic. Subgrade soils were compacted either at their optimum moisture content or at a higher than optimum moisture content to produce different California Bearing Ratios during specimen preparation. Both an extruded biaxial geogrid and woven geotextile were placed at various locations to investigate the optimal placement locations for different subgrade conditions. Pressure sensors were installed near the bottom of the aggregate base layer and near the top of the subgrade layer to monitor the variations in vertical stress within the pavement system under rolling-wheel load. Further, light weight deflectometer measurements were collected post-test to determine the effect of the geosynthetic on pavement foundation stiffness. The vertical pressure at the bottom of the aggregate base and top of subgrade decreased on average approximately 15.3% and 18.8%, respectively. The results indicate which type of geosynthetic and placement location provides the greatest reduction of pressure for each of the given subgrade conditions.

scholarly journals Numerical Simulations of Effects of Soil Moisture and Modification by Mountains over New Zealand in Summer

2011 ◽  
Vol 139 (2) ◽  
pp. 494-510 ◽  
Author(s):  
Yang Yang ◽  
Michael Uddstrom ◽  
Mike Revell ◽  
Phil Andrews ◽  
Hilary Oliver ◽  
...  
Keyword(s):  
Soil Moisture ◽  
New Zealand ◽  
Moisture Content ◽  
Air Temperature ◽  
Land Surface ◽  
Soil Moisture Content ◽  
Surface Air Temperature ◽  
Shortwave Radiation ◽  
Lower Sensitivity ◽  
The South

Abstract Historically most soil moisture–land surface impact studies have focused on continents because of the important forecasting and climate implications involved. For a relatively small isolated mountainous landmass in the ocean such as New Zealand, these impacts have received less attention. This paper addresses some of these issues for New Zealand through numerical experiments with a regional configuration of the Met Office Unified Model atmospheric model. Two pairs of idealized simulations with only contrasting dry or wet initial soil moisture over a 6-day period in January 2004 were conducted, with one pair using realistic terrain and the other pair flat terrain. For the mean of the 6 days, the differences in the simulated surface air temperature between the dry and moist cases were 3–5 K on the leeside slopes and 1–2 K on the windward slopes and the central leeside coastal region of the South Island in the afternoon. This quite nonuniform response in surface air temperature to a uniformly distributed soil moisture content and soil type is mainly attributed to modification of the effects of soil moisture by mountains through two different processes: 1) spatial variation in cloud coverage across the mountains ranges leading to more shortwave radiation at ground surface on the leeside slope than the windward slope, and 2) the presence of a dynamically and thermally induced onshore flow on the leeside coast bringing in air with a lower sensitivity to soil moisture. The response of local winds to soil moisture content is through direct or indirect effects. The direct effect is due to the thermal contrast between land and sea/land shown for the leeside solenoidal circulations, and the indirect effect is through the weakening of the upstream blocking of the South Island for dryer soils shown by the weakening and onshore shift of the upstream deceleration and forced ascent of incoming airflow.

Compaction Characteristic of Lime Modified Expansive Soil

2013 ◽  
Vol 710 ◽  
pp. 348-351
Author(s):  
Zheng Rong Zhao ◽  
Lei Wang ◽  
Hong Xia Yang
Keyword(s):  
Moisture Content ◽  
Expansive Soil ◽  
Size Composition ◽  
Optimum Moisture Content ◽  
Dry Density ◽  
Content Increase ◽  
Maximum Dry Density ◽  
Compaction Curve ◽  
Compaction Characteristic ◽  
Two Peaks

Through compaction test discussed about the compaction characteristics of expansive soil by lime modified in middle of Shandong province. The results show that the optimum moisture content is lower when the expansive soil is cured by dry compaction method, and the maximum dry density is higher. Compaction curve appeared the phenomenon of two peaks when expansive soil is cured by wet compaction method.Lime content of lime improved expansive soil, particle size composition, age and compaction function have influence on compaction curve.With the increase of the quantity of lime, the optimum moisture content increases, the maximum dry density decreases. With the age growth, the optimum moisture content increase slightly,the maximum dry density decreases slightly. The bigger the compaction work, the smaller moisture content is, the larger the maximum dry density is.

Adaptive Importance of Mesocotyl and Coleoptile Growth in Rice Under Different Moisture Regimes.

1978 ◽  
Vol 5 (4) ◽  
pp. 511 ◽  
Author(s):  
N Takahashi
Keyword(s):  
Moisture Content ◽  
Adaptive Response ◽  
Optimum Moisture Content ◽  
Ethylene Formation ◽  
Coleoptile Growth ◽  
Moisture Regimes ◽  
Mesocotyl Elongation ◽  
Endogenous Ethylene ◽  
Water Tension ◽  
Submerged Conditions

The lengths of mesocotyls (first internodes) and coleoptiles of rice varied greatly with the moisture content of the seed-bed. The optimum moisture content in most Indica cultivars was much higher for coleoptile than for mesocotyl growth, but not in some Japonica cultivars because the mesocotyl growth was not vigorous and did not vary with water content. Under submerged conditions, coleoptile growth was markedly stimulated, particularly in Japonica cultivars but there was no mesocotyl elongation in either cultivar. The plastic variability in the growth of coleoptile, leaves, mesocotyl and other internodes may be an adaptive response of rice to the water tension of the soil. Endogenous ethylene formation and effects of ethylene and carbon dioxide were also studied.

Atrazine mineralisation in New Zealand topsoils and subsoils: influence of edaphic factors and numbers of atrazine-degrading microbes

Soil Research ◽  
1998 ◽  
Vol 36 (4) ◽  
pp. 557 ◽  
Author(s):  
Graham Sparling ◽  
Robert Dragten ◽  
Jackie Aislabie ◽  
Rhonda Fraser
Keyword(s):  
New Zealand ◽  
Moisture Content ◽  
Cation Exchange Capacity ◽  
Surface Soil ◽  
Exchange Capacity ◽  
Most Probable Number ◽  
Edaphic Factors ◽  
Decomposition Rates ◽  
Decomposition Products ◽  
Probable Number

The mineralisation of 14C-ring-labelled atrazine to 14CO2 was measured in 3 contrasting New Zealand soils under controlled conditions of temperature and moisture. The numbers of atrazine-degrading organisms were measured by a most probable number technique. Decomposition rates were slow, with a maximum of 41% of atrazine being mineralised over 263 days. Mineralisation was generally very low in subsoils and was much reduced by low moisture content. However, one subsoil from 60–90 cm depth had unusually high numbers of atrazine-degrading microbes and showed mineralisation greater than or equivalent to the surface soil. Mineralisation was approximately doubled by a 10°C rise in temperature over the range 16–28°C. In general, the rate of atrazine mineralisation over 7–96 days could be predicted from the number of atrazine-degrading microbes and the cation exchange capacity of the soil (R2 = 0·86). A large amount (54–77%) of 14C remained in the soil as non-extractable residues after 263 days, but only trace amounts of the added atrazine or the decomposition products de-ethyl atrazine and de-isopropyl atrazine were detected by extraction in organic solvent.

scholarly journals Modeling the Resilient Modulus Variation of In Situ Soils due to Seasonal Moisture Content Variations

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Kevin Gaspard ◽  
Zhongjie Zhang ◽  
Gavin Gautreau ◽  
Khalil Hanifa ◽  
Claudia E. Zapata ◽  
...  
Keyword(s):  
Moisture Content ◽  
Resilient Modulus ◽  
Optimum Moisture Content ◽  
Test Method ◽  
Large Scatter ◽  
Controlling Parameter ◽  
Base Course ◽  
The Relationship ◽  
Level 2

LTRC is conducting a research project to determine the seasonal variation of subgrade resilient modulus (MR) in an effort to implement PavementME. One objective of that project, which is presented in this paper, was to locally calibrate the Enhanced Integrated Climate Model’s (EICM Fenv) curve for seasonal subgrade MR changes. Shelby tube sampling was conducted on six different roadways to a depth of approximately 7.92 m beneath the shoulder pavement’s base course. The AASHTO T-99 MR test method was used on all samples with an additional eight specimens being tested with NCHRP 1–28A MR test method. Four soils from Louisiana which were not from the six roadways were also tested and included in the analyses. Once the MR tests were completed and plotted, it was noticed that there was a rather large scatter (R2 = −0.266) around the EICM Fenv curve. The authors hypothesized that this occurred due to the density differences between in situ and remolded specimens. Further analyses confirmed this hypothesis. LTRC developed a new method based on the EICM Fenv method to determine the relationship between changes in subgrade MR as a function of changes in moisture content with the in situ moisture content and MR used as the control. This method differs from the EICM Fenv in that the EICM Fenv uses optimum moisture content as the controlling parameter. The LTRC method can be used for design purposes as well as level 2 inputs into the EICM.

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