Enhanced Strength Properties of Dredged Marine Sediments Using Electrokinetic Stabilization Method

2020 ◽  
Vol 997 ◽  
pp. 37-45
Author(s):  
Nurul Syakeera Nordin ◽  
Chee Ming Chan
Keyword(s):  
Moisture Content ◽  
Marine Sediments ◽  
Strength Properties ◽  
Strength Increase ◽  
High Plasticity ◽  
Stabilizing Agents ◽  
Access Channel ◽  
Dry Zone ◽  
Electrokinetic Stabilization ◽  
Maintenance Dredging

Nearshore’s facilities are often require frequent and regular maintenance dredging in maintaining appropriate water depths and enlarging the access channel and turning basin. A large amount of sediment was spawned from the dredging work. The dredged marine sediments (DMS) are not apt to be used in construction activities because of its poor geophysical properties. The purpose of this research is to study the improvement in moisture content and strength of DMS by using electrokinetic (EK) method. DMS are classified as a high plasticity silt (MH) with 240.74 % of its natural water content. Stainless steel plate was invoked as the electrode, while distilled water (DW), citric acid (CA) and calcium chloride (CaCl2) were applied as the stabilizing agents. The aforementioned stabilizers are electrically injected into the DMS which causing flow of the solutions through the pores in DMS under 50 V/m of applied direct current (DC). The results of treated DMS are presented in moisture content, undrained shear strength and SEM-EDX analysis. The EK treated DMS shows it increases in strength in the dry zone area after the 14 days treatment. The dry zone area was created near the anode and wet zone was made near the cathode. The application of calcium ions in the treatment had increased the strength and alters the pattern of the soil fabric. Largely, EK has significantly improved the quality of DMS even though the strength increase observed was not homogeneous throughout the specimen.

Influence of Active Filler, Curing Time and Moisture content on the Strength Properties of Emulsion and Foamed Bitumen Stabilized Mix

2014 ◽  
Vol 70 (4) ◽  
Author(s):  
Zulakmal Sufian ◽  
Nafisah A. Aziz ◽  
Mohd Yazip Matori ◽  
Mat Zain Hussain ◽  
Mohd Rosli Hainin ◽  
...  
Keyword(s):  
Moisture Content ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Resilient Modulus ◽  
Asphalt Pavement ◽  
Strength Properties ◽  
Curing Time ◽  
Stabilizing Agents ◽  
Active Filler ◽  
Foamed Bitumen

Foamed bitumen and emulsion are common stabilizing agents that are currently used for recycled asphalt pavement construction throughout the world. The strength of stabilized Reclaimed Asphalt Pavement (RAP) is influenced by factors such as filler content, moisture level and curing time. This paper describes the strength impact of ordinary Portland cement as active filler, the length of the curing time and moisture content on the foamed bitumen and emulsion stabilized mix. The basic objective of the paper is to evaluate the effect of active filler (Ordinary Portland Cement), curing time and moisture content on the strength of foamed bitumen and emulsion treated mix. The foamed and emulsion treated samples with various contents of RAP and crushed stone aggregates were tested for their strength properties. The resultant strength increases in terms of resilient modulus, Unconfined Compressive Strength (UCS) and the Indirect Tensile Strength (ITS) values, were correlated with the length of curing time, using various percentages of active filler and proportions of RAP in the pavement mix. It was found that the strength decreased with increased RAP content, however if 100% RAP is to be used then the required pavement strength can be achieved by utilizing a higher active filler ratio. The effect of moisture content variation on foamed bitumen and emulsion treated samples with high percentage of RAP is not significant.

Co-cooking nonwoods with hardwoods

TAPPI Journal ◽  
2014 ◽  
Vol 13 (6) ◽  
pp. 19-24
Author(s):  
TROY RUNGE ◽  
CHUNHUI ZHANG
Keyword(s):  
High Performance Liquid Chromatography ◽  
High Performance ◽  
Paper Industry ◽  
Pulp And Paper Industry ◽  
Strength Properties ◽  
Agricultural Residues ◽  
Kraft Pulping ◽  
Pulp And Paper ◽  
Strength Increase ◽  
Xylan Content

Agricultural residues and energy crops are promising resources that can be utilized in the pulp and paper industry. This study examines the potential of co-cooking nonwood materials with hardwoods as means to incorporate nonwood material into a paper furnish. Specifically, miscanthus, switchgrass, and corn stover were substituted for poplar hardwood chips in the amounts of 10 wt %, 20 wt %, and 30 wt %, and the blends were subjected to kraft pulping experiments. The pulps were then bleached with an OD(EP)D sequence and then refined and formed into handsheets to characterize their physical properties. Surprisingly, all three co-cooked pulps showed improved strength properties (up to 35%). Sugar measurement of the pulps by high-performance liquid chromatography suggested that the strength increase correlated with enriched xylan content.

scholarly journals Moisture-Dependent Strength Properties of Thermally-Modified Fraxinus excelsior Wood in Compression

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1647 ◽  
Author(s):  
Edward Roszyk ◽  
Elżbieta Stachowska ◽  
Jerzy Majka ◽  
Przemysław Mania ◽  
Magdalena Broda
Keyword(s):  
Moisture Content ◽  
Strength Properties ◽  
Treatment Temperature ◽  
Thermal Modification ◽  
Fraxinus Excelsior ◽  
Mechanical Parameters ◽  
Saturation Point ◽  
Wood Moisture ◽  
Intrinsic Anisotropy ◽  
European Ash

European ash (Fraxinus excelsior L.) is one of the species commonly used for wood thermal modification that improves its performance. The presented research aimed to investigate a moisture-dependent strength anisotropy of thermally-modified European ash in compression. Wood samples were modified at 180 °C and 200 °C. Their mechanical parameters were determined in the principal anatomical directions under dry (moisture content of 3%) and wet (moisture content above fibre saturation point) conditions. Effect of heat treatment temperature and moisture content on the ash wood mechanical parameters concerning each anatomical direction were determined. The results show that thermal treatment kept the intrinsic anisotropy of wood mechanical properties. It decreased wood hygroscopicity, which resulted in improved strength and elasticity measured for wet wood when compared to untreated and treated samples. Higher treatment temperature (200 °C) increased wood elasticity in compression in all the anatomical directions despite wood moisture content during the measurements. Multivariate analysis revealed that the modification temperature significantly affected the modulus of elasticity perpendicular to the grain, while in the case of compression strength, the statistically significant effect was observed only parallel to the grain. The results obtained can be useful from an industrial perspective and can serve as part of a database for further modelling purposes.

Technological Properties of Wood from Trees in Polluted Regions

IAWA Journal ◽  
1986 ◽  
Vol 7 (4) ◽  
pp. 389-397 ◽  
Author(s):  
A. Frühwald
Keyword(s):  
Moisture Content ◽  
Wood Quality ◽  
Wood Properties ◽  
Biological Indicators ◽  
Strength Properties ◽  
West Germany ◽  
Technological Properties ◽  
Growth Rings ◽  
Physical Chemical ◽  
Faster Development

Wood quality from about 230 healthy and diseased fir, spruce, pine and beech trees from various locations in West Germany was tested. In general results are satisfactory for mechanical wood properties, but some physical, chemical and biological indicators lead to the conclusion that logs from heavily diseased trees may be attacked a !ittle earlier and faster by microorganisms during storage. Width of growth rings is reduced in severely damaged softwood trees on most locations whereas beech shows no significant reduction. Declining health of the trees had no or little influence on wood density; the modulus of elasticity and strength were at normal levels and independent of tree damage. Width and moisture content of sapwood were reduced little in pines but more in spruce and fir. A tendency to a more intensely developed irregular brown heartwood in severeIy damaged beech trees could not be proved until now. Storage of spruce in a log yard for four months has shown a slightly faster development of discoloration caused by fungi in diseased trees whereas after seven months wood from healthy trees was more discoloured. After storage strength properties are not or only slightly reduced, but no difference was found between trees assigned to the various health classes. After two years of storage under sprinkling water, pine logs from healthy and diseased trees show no difference in discoloration.

scholarly journals Tensile response and fracturing process in moderate- and high-plasticity clays

2020 ◽  
pp. 1-11
Author(s):  
Giulia Forlati ◽  
Paul Shepley
Keyword(s):  
Moisture Content ◽  
Fracture Behaviour ◽  
Soil Layer ◽  
Clay Soils ◽  
Tensile Fracture ◽  
Future Research ◽  
High Plasticity ◽  
Bending Tests ◽  
Fracturing Process ◽  
The Difference

Sinkholes in clay soils can be considered as the collapse of a soil layer previously bridging a void. Here, flexural deformation in the clay drives the formation of tensile cracks from the lowest surface of the layer and the consequent soil collapse is from crack propagation. Considering a simplified model of the sinkhole geometry, this paper aims to describe the tensile and fracture behaviour of clay soils with different plasticity indices. Speswhite kaolin, London, and Durham clays were tested using direct tensile and bending tests. Moderate- and high-plasticity clays showed a nonlinear fracture response with increasing moisture content, while low-plasticity clays demonstrated a linear response. Bending tests confirmed the importance of the moisture content while the plasticity index confirmed the difference in ductile or fragile collapse for fracture propagation. To assess the results, elasto-plastic fracture mechanics (EPFM) theory was applied to clays with appropriate modifications. The analysis demonstrated that EPFM theory provides a good baseline for predicting tensile fracture behaviour in clay soils, which can be extended in future research.

scholarly journals Shear Strength of Compacted Clays as Affected by Mineral Content and Wet-Dry Cycles

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Frederick Nai Charkley ◽  
Kunyong Zhang ◽  
Guoxiong Mei
Keyword(s):  
Shear Strength ◽  
Clay Minerals ◽  
Mineral Content ◽  
Strength Properties ◽  
High Plasticity ◽  
Wetting And Drying ◽  
Frictional Strength ◽  
Precautionary Measures ◽  
Weather Changes ◽  
Clay Slopes

The behaviors of high-plasticity clays depend largely on the clay mineral content. Recently, it has been observed that sudden slope failures of most clay slopes occur in regions pronounced with repeated rainfall and sunny climate. The reason for this is still unclear. Examining the effect of clay minerals and drastic weather changes on shear strength will be useful in predicting the performance of structures built in such soils and to take precautionary measures to improve the properties before failure. Therefore, a series of quick direct shearing tests were conducted on 11 artificial clay mixtures. The cohesion and frictional strength properties were determined and linked to the proportion of clay minerals and the number of wetting and drying cycles. The results show a significant reduction in shear strength after exposure to wetting and drying. Generally, montmorillonite-dominated mixtures were less susceptible to the changes in cohesion strength than kaolin-dominated mixtures, and the reduction in frictional strength was relatively insignificant.

scholarly journals Experimental Study on the Efficacy of Water Infusion for Underground Mining of a Coal Seam

2019 ◽  
Vol 9 (18) ◽  
pp. 3820 ◽  
Author(s):  
Nguyen ◽  
Nguyen ◽  
Do
Keyword(s):  
Experimental Study ◽  
Moisture Content ◽  
Coal Seam ◽  
Field Test ◽  
Underground Mining ◽  
Water Injection ◽  
Strength Properties ◽  
Water Infusion ◽  
Coal Wall ◽  
Infusion Method

The main purpose of this study is to evaluate the efficacy of the water infusion method for various coalfaces of a coal seam by an experimental study. First, laboratory tests were performed on several coal samples taken from actual coalfaces to determine the general characteristics, especially the strength properties, with respect to the moisture content and time. The results obtained from the laboratory were employed to evaluate the appropriate parameters (e.g., water injection time and the optimum moisture content) for water infusion works in the field. A field test was then performed in order to assess the efficacy of water infusion for underground mining. The spalling depth (i.e., longwall face failure of coal wall, involving the stability of underground mining coalfaces) and mining velocity (i.e., involving the cost-effectiveness of mining constructions) were monitored at various coalfaces for both case studies (i.e., with and without water infusion). Expectedly, the field test results revealed that the spalling depth decreased significantly, whereas the mining velocity sped up considerably, at coalfaces using water infusion compared to at those without using the water infusion method. In conclusion, the promising findings obtained from the field test reinforced the efficacy of water infusion for underground mining coalfaces.

Undrained shear strength properties of organic harbor mud at low consolidation stress levels

2011 ◽  
Vol 48 (3) ◽  
pp. 388-398 ◽  
Author(s):  
Benjamin Friedrich Schlue ◽  
Tobias Mörz ◽  
Stefan Kreiter
Keyword(s):  
Shear Strength ◽  
Large Scale ◽  
Strength Properties ◽  
Undrained Shear Strength ◽  
Ex Situ ◽  
High Plasticity ◽  
Compression Time ◽  
Stress Levels ◽  
Strong Surface ◽  
Undrained Shear

Dredging operations in European harbors for maintenance of navigable water depth produce vast amounts of harbor mud. Between 2005 and 2007, the second largest harbor construction project in Germany was designed as a pilot study, using dredged harbor mud as backfill material to avoid expensive deposition or ex situ treatment. During this project, strong surface deformations of the backfill highlighted the need for an improved assessment of undrained shear strength of naturally liquid harbor mud. The strength of harbor mud cannot be measured accurately under corresponding low in situ effective stress levels by standard laboratory tests. Therefore, a large-scale oedometer cell with a diameter of 22 cm was designed, providing the opportunity to perform vane shear measurements during consolidation. This study shows that East Harbor mud is a very sensitive, organogenic clay of extremely high plasticity, exhibiting very small undrained shear strength when compared with other cohesive soils. Both the peak and residual undrained shear strengths are shown to increase about 3%–4% per log-cycle increase in secondary compression time (days).

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