scholarly journals Laboratory study of small-strain behavior of a compacted silty sand

2013 ◽  
Vol 50 (2) ◽  
pp. 179-188 ◽  
Author(s):  
Ana Heitor ◽  
Buddhima Indraratna ◽  
Cholachat Rujikiatkamjorn
Keyword(s):  
Moisture Content ◽  
Structural Changes ◽  
Initial Moisture Content ◽  
Small Strain ◽  
Matric Suction ◽  
Point Of View ◽  
Silty Sand ◽  
Degree Of Saturation ◽  
Compacted Soil ◽  
Strain Behavior

Small-strain behavior is a key indicator for assessing the performance of compacted fills. Compaction conditions, i.e., initial moisture content and applied energy, govern compaction effectiveness and thus, the structure and matric suction of compacted soil. This paper presents an experimental study of the small-strain behavior of compacted silty sand prepared with different compaction conditions. Specimens with varying initial moisture contents and compaction energies were tested with bender elements to determine the small-strain shear modulus (G0), while the post-compaction matric suction was measured using the filter paper method and tensiometer. The experimental data suggest a pronounced relationship between G0 and the degree of saturation (Sr) of the as-compacted soil specimens. X-ray computed tomography (CT) scans were performed to examine structural changes of selected specimens upon compaction. The laboratory results are also examined in light of common end-product specifications, which show that it is beneficial to compact the soil slightly dry of optimum moisture content from the modulus point of view.

scholarly journals Modelling the moisture sorption isotherms of Roselle (Hibiscus sabdariffa L.) in the temperature range of 5–35 °C

2013 ◽  
Vol 61 (6) ◽  
pp. 1769-1777 ◽  
Author(s):  
Jitka Langová ◽  
Donludee Jaisut ◽  
Ratiya Thuwapanichayanan ◽  
Charotorn Phowong ◽  
Jiří Štencl ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Sorption ◽  
Structural Changes ◽  
Sorption Isotherms ◽  
Moisture Sorption ◽  
Ambient Air ◽  
Point Of View ◽  
Hibiscus Sabdariffa ◽  
Adsorption And Desorption ◽  
Moisture Sorption Isotherms

Water sorption tests of Roselle (Hibiscus sabdariffa L.) carried out under laboratory conditions are presented together with mathematical analyses of the moisture sorption isotherms (MSI’s). Moisture equilibrium data for adsorption and desorption of water from Roselle powder were investigated at near ambient air temperatures in the range of 5 and 35 °C and water activity (Aw) ranging from 0.11 to 0.97. The manometric method has been used for water sorption tests. Models for MSI’s are exponential equations. Coefficients of determination are 0.998 and 0.996 (for adsorption and desorption at 5 °C, respectively), 0.998 and 0.999 (for adsorption and desorption at 20 °C, respectively), and 0.998 and 0.999 (for adsorption and desorption at 35 °C, respectively). The equilibrium moisture content (EMC) of Roselle samples increased with an increase of Aw at a constant temperature both for adsorption and desorption. Adsorption curve equates to desorption curve at higher temperatures of tests carried out. Critical values of EMC of samples tested corresponding to the Aw equal to 0.6 were between 13.401% moisture content wet basis (MC w.b.) and 15.934% MC (w.b.) for moisture adsorption and desorption, respectively. These values are useful for storing conditions optimisation from point of view microorganisms grow and structural changes analyses. Crystal structure changes were observed during adsorption and desorption in the microscope, too. It was found out glass transition in dependence on the water content of samples tested.

scholarly journals Effect of soil moisture content on the bearing capacity of small bored piles in the unsaturated soil of Maringá, Paraná, Brazil

2021 ◽  
Vol 337 ◽  
pp. 03006
Author(s):  
Verônica Ricken Marques ◽  
Antonio Belincanta ◽  
Mary-Antonette Beroya-Eitner ◽  
Jorge Luis Almada Augusto ◽  
Ewerton Guelssi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Bearing Capacity ◽  
Water Content ◽  
Unsaturated Soil ◽  
Soil Layer ◽  
Matric Suction ◽  
Load Test ◽  
Degree Of Saturation ◽  
Static Load Test

In this study, the influence of soil moisture on the bearing capacity of piles founded in an unsaturated clay soil was investigated. The soil studied, composing the upper soil layer in Maringá, Brazil, is lateritic, has degree of saturation between 37% and 70% and has collapsible behaviour when wet. The bearing capacity was determined by full-scale load tests following the Brazilian Standard for Static Load Test. Two pile lengths, 4 m and 8 m, were considered. To analyse the influence of soil moisture, two tests were performed for each pile length: one in soil in its natural moisture content and another in pre-moistened soil. Results show that for both pile lengths, an increase in water content caused a significant reduction in bearing capacity, which is attributed to the decrease in the matric suction of the soil. This is confirmed by the results of the initial evaluation made on the variation of matric suction and its contribution to the bearing capacity with changes in water content. In summary, this study confirms that the pile bearing capacity in unsaturated soil is dependent on soil water content, highlighting the fact that the approach of assuming full saturation condition in the evaluation of the pile bearing capacity in such soil may give erroneous results. Moreover, this study demonstrate that the empirical methods most commonly used in Brazil for pile bearing capacity determination, the Décourt & Quaresma and Aoki & Velloso methods, are overly conservative when applied to the Maringá soil.

scholarly journals Effect of Reinforcement on Properties of Silty Sand

2021 ◽  
Vol 9 (12) ◽  
pp. 1934-1938
Author(s):  
Dr. G. Sireesha
Keyword(s):  
Moisture Content ◽  
Normal Stress ◽  
Axial Strain ◽  
Optimum Moisture Content ◽  
Silty Sand ◽  
Dry Density ◽  
Maximum Dry Density ◽  
Strain Behavior ◽  
Deviator Stress ◽  
Water Contents

Abstract: The variation of the stress-strain behavior and shear -parameters of reinforced silty sand is studied. The geotextiles were provided at different heights in the sample and tested in unconsolidated undrained condition. Two types of geotextiles, woven and nonwoven were used as reinforcement and the experiment was conducted at three water contents. Tests were performed on samples prepared at OMC, dry of OMC and wet of OMC in order to study the effect of water content. The results demonstrated that geotextile inclusion increases the peak strength, axial strain at failure. The sample was found to fail due to bulging between the layers. Keywords: Optimum Moisture Content, Maximum Dry Density, Unconsolidated Undrained, Deviator Stress, Normal Stress

scholarly journals Modelling resilient modulus seasonal variation of silty sand subgrade soils with matric suction control

2014 ◽  
Vol 51 (12) ◽  
pp. 1413-1422 ◽  
Author(s):  
Farhad Salour ◽  
Sigurdur Erlingsson ◽  
Claudia E. Zapata
Keyword(s):  
Stress State ◽  
Moisture Content ◽  
Prediction Model ◽  
Pore Pressure ◽  
Resilient Modulus ◽  
Matric Suction ◽  
Pressure Effects ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Suction Control

The resilient modulus of unbound materials is an important parameter in the mechanistic design of pavements. Although unbound layers are frequently in a partially saturated state, a total stress approach is conventionally used in modeling the material behaviour, and therefore pore pressure effects are not considered. In fine-grained unbound materials, the saturation state can affect their mechanical behaviour due to pore pressure effects. In this study a modified test procedure and a predictive resilient modulus model that takes into account the subgrade soil matric suction as a stress state variable is presented. Two different silty sand subgrade materials were tested in unsaturated conditions using a series of repeated load triaxial tests under controlled pore suction conditions to study its influence on the resilient modulus. The test data were further used to obtain the resilient modulus model regression parameters that account for moisture content variations through the matric suction parameter. Generally, the prediction model could effectively capture the resilient modulus behaviour of the subgrades with respect to changes in the normal stress state and the matric suction. Given the completeness of this method, this prediction model is recommended as an improved approach in capturing the moisture content effects on the material stiffness properties.

Small strain behavior of a silty sand in controlled-suction resonant column – torsional shear tests

2002 ◽  
Vol 39 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Claudio Mancuso ◽  
Roberto Vassallo ◽  
Anna d'Onofrio
Keyword(s):  
Shear Stiffness ◽  
Small Strain ◽  
Bulk Water ◽  
Silty Sand ◽  
Resonant Column ◽  
Soil Behavior ◽  
Soil Response ◽  
Strain Behavior ◽  
Torsional Shear ◽  
Constant Suction

An experimental study has been carried out using a new resonant column – torsional shear cell to investigate the small strain behavior of an unsaturated compacted silty sand. The device, recently developed at the Dipartimento di Ingegneria Geotecnica di Napoli (Italy), is fitted for controlled-suction testing using the axis-translation technique. Both optimum and wet of optimum compacted specimens have been tested to analyze the effects of suction and fabric on soil behavior. Shear stiffness measurements have been taken during constant-suction tests. Collected data indicate an S-shaped initial shear stiffness versus suction variation, which can be explained considering the progressive change from a bulk-water regulated soil response to a menisci-water regulated soil response. A model is proposed to account for the observed trend. Results highlight significant effects of suction and fabric on soil behavior.Key words: compacted soil, small strain behavior, shear stiffness, suction, soil fabric.

scholarly journals Effect of Extrusion Temperature and Feed Moisture Content on the Microstructural Properties of Rice-Flour Pellets and Their Impact on the Expanded Product

Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 198
Author(s):  
Yadira Zambrano ◽  
Ingrid Contardo ◽  
María Carolina Moreno ◽  
Pedro Bouchon
Keyword(s):  
Moisture Content ◽  
Structural Changes ◽  
Initial Moisture Content ◽  
Rice Flour ◽  
Extrusion Temperature ◽  
Micro Ct ◽  
Processing Conditions ◽  
Microstructural Properties ◽  
Cooking Temperature ◽  
Feed Moisture

Extrusion can lead to an expanded product or to a slightly expanded pellet, known as a third-generation (3G) snack. In this case, expansion occurs subsequently, in an independent thermal device (e.g., oven), out of the extruded pellet. During both processes, several structural changes occur which are linked to processing conditions, including cooking temperature, screw speed, formulation, and initial moisture content. However, a clear relationship between processing variables and the structure of pellets and expanded products has not yet been identified. Accordingly, this work aimed to study the effect of extrusion temperature (110, 135, and 150 °C) and moisture content (27, 29, and 31%) in rice-flour pellets and their microwave expansion, through a microstructural approach using micro-CT. The results showed that the lowest moisture content (27%) and the highest extrusion temperature (150 °C) led to the highest pellet volume and the highest wall thickness, which in turn led to the highest expansion after microwave heating (50 s, 800 W). Interestingly, no significant differences were observed when analyzing the ratio between the volume of the expanded products and the volume of the pellet (~2.4) when using the different processing conditions.

Infiltration and structural changes as influenced by initial moisture content

Soil Research ◽  
1971 ◽  
Vol 9 (2) ◽  
pp. 107 ◽  
Author(s):  
N Collis-George ◽  
R Lal
Keyword(s):  
Moisture Content ◽  
Structural Changes ◽  
Initial Moisture Content ◽  
Infiltration Rate ◽  
Surface Layers ◽  
Infiltration Process ◽  
Moisture Condition ◽  
Heat Of Wetting ◽  
Cumulative Infiltration ◽  
Entrapped Air

The variation of infiltration behaviour, in columns of aggregates of a structurally stable and an unstable soil, caused by pre-equilibrating the aggregates with a range of relative humidities from 0 to 98%, was measured in terms of advance of the front, cumulative infiltration, slaking, and swelling. In this range, the effect of initial moisture condition on the stable soil (krasnozem) was slight compared with that on the unstable soil (black earth); the wetter the soil initially, the greater was the infiltration rate, and the smaller the slaking and swelling. The change in the behaviour of infiltration into systems of stable aggregates is reflected as (1) an increase in the importance of the sorptivity, and (2) a reduction in the importance of the hydraulic conductivity contribution to the steady-state infiltration process. (The aggregates of 1/2-1 mm are of such a size that the sorptivity contribution should not normally be detectable in stable soils.) It is suggested that in the unstable soil, the heat of wetting is associated with aggregate collapse. The degraded structure of the surface layers prevents fast entry of water into the lower layers. The collapse of structure dominates the infiltration process so that the analysis in terms of sorptivity carried out for stable aggregates cannot be made. The effect of entrapped air on slaking of aggregates of these soils is shown to be negligible compared with the effect of initial moisture content. The application of the results to flood irrigation of unstable soils under field conditions is briefly considered.

Examination of Tobacco Hygroscopicity / Über die Hygroskopizität des Tabaks

1965 ◽  
Vol 3 (1) ◽  
Author(s):  
L. Hübschen
Keyword(s):  
Moisture Content ◽  
Sorption Isotherm ◽  
Initial Moisture Content

AbstractThe present paper shows the detectable factors on which a sorption isotherm depends. Even if it is well-known that a sorption isotherm is most essentially conditioned by influences of the respective tobacco variety, other factors, such as temperature, initial moisture content, or fibre dimension, play a part as well. In general, a sorption isotherm constitutes a ''summation'' of such factors and, in the end, a combination of desorption and adsorption if the tobacco is dried or moistened from the average commercial moisture content. The tobacco hysteresis is experimentally investigated and discussed

Pengeringan Biji Kakao dengan Pengering Surya Tipe Terowong Berpenggerak Sel Fotovoltaik di Manokwari

Agrotek ◽  
2018 ◽  
Vol 2 (6) ◽  
Author(s):  
Wilson Palelingan Aman
Keyword(s):  
Moisture Content ◽  
Performance Test ◽  
Initial Moisture Content ◽  
Maximum Temperature ◽  
Photovoltaic Module ◽  
Cocoa Beans ◽  
Drying Time ◽  
Tunnel Dryer ◽  
Heat Collector ◽  
New Construction

<em>A research about cocoa beans drying used solar tunnel dryer with photovoltaic module driven have conducted in Manokwari. Solar tunnel dryer used in this research adapted from type Hohenheim with photovoltaic module and integrated air heat collector has been installed at the Department of Agricultural Technology, Papua State University Manokwari to dried cocoa beans. The objectives of this research were to design solar tunnel dryer and evaluate it�s performance in dryed cocoa beans. The result obtained was a new construction of solar tunnel dryer for cocoa beans with dimensions 6 m of length and 0,9 m of wide. The dryer completed with photovoltaic module to drive the blowers of hot drying air. �Performance test of the dryer showed that drying of 10 kg of cocoa beans with initial moisture content about 70% wet basis needed 13 hours of drying time to achieved final moisture content about 7,17% wet basis. The drying time achieved was faster compared than traditional solar drying that needed 20 hours of drying time. The maximum temperature achieved in drying chamber was 60 <sup>o</sup>C.</em>

scholarly journals Wood Chip Drying through the Using of a Mobile Rotary Dryer

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1590 ◽  
Author(s):  
Angelo Del Giudice ◽  
Andrea Acampora ◽  
Enrico Santangelo ◽  
Luigi Pari ◽  
Simone Bergonzoli ◽  
...  
Keyword(s):  
Moisture Content ◽  
Power Plants ◽  
Black Locust ◽  
Thermal Power ◽  
Initial Moisture Content ◽  
Wood Chip ◽  
Wood Chips ◽  
Cocurrent Flow ◽  
Drying Process ◽  
Rotary Dryer

Drying is a critical point for the exploitation of biomass for energy production. High moisture content negatively affects the efficiency of power generation in combustion and gasification systems. Different types of dryers are available however; it is known that rotary dryers have low cost of maintenance and consume 15% and 30% less in terms of specific energy. The study analyzed the drying process of woody residues using a new prototype of mobile rotary dryer cocurrent flow. Woodchip of poplar (Populus spp.), black locust (Robinia pseudoacacia L.), and grapevine (Vitis vinifera L.) pruning were dried in a rotary drier. The drying cycle lasted 8 h for poplar, 6 h for black locust, and 6 h for pruning of grapevine. The initial biomass had a moisture content of around 50% for the poplar and around 30% for grapevine and black locust. The study showed that some characteristics of the biomass (e.g., initial moisture content, particle size distribution, bulk density) influence the technical parameters (i.e., airflow temperature, rate, and speed) of the drying process and, hence, the energy demand. At the end of the drying process, 17% of water was removed for poplar wood chips and 31% for grapevine and black locust wood chips. To achieve this, result the three-biomass required 1.61 (poplar), 0.86 (grapevine), and 1.12 MJ kgdry solids−1 (black locust), with an efficiency of thermal drying (η) respectively of 37%, 12%, and 27%. In the future, the results obtained suggest an increase in the efficiency of the thermal insulation of the mobile dryer, and the application of the mobile dryer in a small farm, for the recovery of exhaust gases from thermal power plants.

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