scholarly journals Change in the Mechanic Properties and Electrical Resistivity of High Water Backfill Material under Electrochemical Treatment

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Dongdong Chen ◽  
Yaohui Sun ◽  
Shengrong Xie ◽  
En Wang ◽  
Xiaoyu Wu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Elastic Modulus ◽  
Engineering Application ◽  
Deformation Modulus ◽  
Potential Gradient ◽  
High Water ◽  
Electrochemical Treatment ◽  
Uniaxial Compression Strength ◽  
Electrochemical Modification ◽  
Backfill Material

To modify the mechanic properties of high water backfill material (HWBM) for its engineering application in mining backfill, a series of experiments were performed to investigate the effects of electrochemical treatment on the mechanic properties and electrical resistivity of the HWBM at the early age. Meanwhile, the effects of the potential gradient, power-on time, and water–cement ratio (W/C) on electrochemical modification efficiency were investigated. The results show that the uniaxial compression strength (UCS), elastic modulus, and deformation modulus of the HWBM all first increased and then decreased after electrochemical treatment with the increasing of the potential gradient and power-on time. However, for the HWBM with different W/C, the UCS and electrical resistivity both increased the HWBM except when the W/C was 3 : 1. The elastic modulus and deformation modulus of the samples both increased after electrochemical modification except when the W/C was 4 : 1. Additionally, there is a positive correlation between the UCS and electrical resistivity in HWBM samples. Therefore, it is proved that the electrochemical technology is a potential method for improving the physicochemical properties of the HWBM.

scholarly journals Experimental and mechanistic research on modifying the mechanic properties of the high water backfill material by electrochemical treatment

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shengrong Xie ◽  
Yaohui Sun ◽  
En Wang ◽  
Dongdong Chen ◽  
Xiaoyu Wu ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Deformation Modulus ◽  
Potential Gradient ◽  
High Water ◽  
Electrochemical Treatment ◽  
Engineering Properties ◽  
Factors Affecting ◽  
Calcium Silicate Hydrates ◽  
Peak Points ◽  
Backfill Materials

Abstract To promote the engineering applications of high water backfill materials (HWBM) in mining, a series of experiments are performed to investigate the effects of the direct current (DC) electric field on the mechanic properties and electrical resistivity of HWBMs. Based on X-ray diffraction (XRD) and scanning electron microscopy (SEM) investigations, the influence of electrochemical treatment on the hydration products and the microstructure of the HWBM was studied. The results show that the peak strength, elastic modulus, deformation modulus and electrical resistivity of the HWBM samples all first increased and then decreased with the increasing of the potential gradient, and the peak points appeared when the potential gradient was 0.2 V/cm. The anisotropy of content of ettringite and calcium silicate hydrates (C–S–H) increased betweent the anodic and cathodic regions of samples. Meanwhile, microstructure in the anodic region of the samples was more stable after electrochemical treatment, which indicates that the different variation of mineralogical compositions and microstructures in different regions of the samples are the primary factors affecting the mechanic properties and electrical resistivity of the HWBM. Therefore, the electrochemical method is a potential technology to modify the engineering properties of the HWBM.

Evaluating Mechanical Properties of Cement Materials by Depth-Sensing Indentation Method

2010 ◽  
Vol 44-47 ◽  
pp. 2587-2591
Author(s):  
Xiu Fang Wang ◽  
Yi Wang Bao ◽  
Kun Ming Li ◽  
Yan Qiu ◽  
Xiao Gen Liu
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Energy Dissipation ◽  
Engineering Application ◽  
Calculated Data ◽  
Absorption Capacity ◽  
Cement Industry ◽  
Depth Sensing ◽  
Indentation Method ◽  
Recovery Resistance

The energy consumption of crushing is directly affected by the mechanical properties of cement materials. The elastic modulus, energy dissipation, recovery resistance and other mechanical properties of cement materials are evaluated based on the depth-sensing indentation method in this work. It is significant and efficient for engineering application. In results, the calculated elastic modulus is close to that measured by dynamic method, being used to verify the correctness of the calculated data. And the calculated energy dissipation of clinker is higher than that of limestone and granite, which can partially be used to explain why the grinding of clinker consumes a lot of energy in cement industry. The recovery resistance of clinker is almost identical to that of granite, more than that of limestone. It is found that the clinker, in contrast to granite and limestone, exhibits better plasticity and greater energy absorption capacity.

scholarly journals Evidence for a Till Layer Beneath Storglaciären, Sweden, Based on Electrical Resistivity Measurements

1987 ◽  
Vol 33 (115) ◽  
pp. 311-314 ◽  
Author(s):  
Geoff Brand ◽  
Veijo Pohjola ◽  
Roger Leb. Hooke
Keyword(s):  
Electrical Resistivity ◽  
Water Content ◽  
Marked Reduction ◽  
Heavy Rain ◽  
High Water ◽  
High Water Content ◽  
Similar Composition ◽  
Resistivity Measurements ◽  
Low Resistivity ◽  
Made In

AbstractElectrical resistivity measurements were made in a series of closely spaced holes drilled to the base of Storglaciären. Electrodes were lowered to the bottoms of the holes where they made contact with the substrate beneath the glacier. The measurements show that a layer of till, ~0.4–0.7 m thick, is present at the base of the glacier. The low resistivity of the layer indicates that it has a high water content, compared with tills of similar composition in the pro-glacial environment. A marked reduction in resistivity after a heavy rain storm demonstrates that the water content is sensitive to variations in water input at the surface.

Research on Fully-Enclosed Composite Cable Made with CFRP and High-Tensile Steel Wire

2011 ◽  
Vol 250-253 ◽  
pp. 1927-1931
Author(s):  
Yun Gang Chen ◽  
Zheng Xing Guo ◽  
Han Chang
Keyword(s):  
Elastic Modulus ◽  
Carbon Fiber ◽  
Stress Ratio ◽  
Steel Wire ◽  
Engineering Application ◽  
High Strength ◽  
Coordination Mechanism ◽  
Axial Stiffness ◽  
Forming Technology ◽  
Steel Wires

In this paper, the proposed idea of producing fully-enclosed composite cable with CFRP coupling of high-tensile steel wires and the forming technology of the fully-enclosed composite cable body were introduced. The coordination mechanism of the fully-enclosed composite cable, the requirement of equal elastic modulus between high strength steel wire bundle and CFRP were investigated theoretically. We have come to the follwing conclusions: (1) Carbon fiber has the same strain with the high-tensile steel wire under the tension of whole anchorage. (2) The distribution of the force of the composite cable is in accordance with the axial stiffness between the carbon fiber with high-tensile steel wire. (3) To achieve a good synergy between the carbon fiber with high-tensile steel wire, similar or equivalent elastic modulus is required. (4) The stress ratio between carbon fiber and high-tensile steel wire in the fully-enclosed composite cable in engineering application should be controlled around 0.5.

Material Properties of Thick Aluminum Coating Made by Cold Gas Dynamic Spray Deposition

2007 ◽  
Vol 345-346 ◽  
pp. 1097-1100
Author(s):  
Jae Chul Lee ◽  
Doo Man Chun ◽  
Sung Hoon Ahn ◽  
Caroline S. Lee
Keyword(s):  
Electrical Resistivity ◽  
Elastic Modulus ◽  
Cold Spray ◽  
Material Properties ◽  
Gas Dynamic ◽  
Macro Scale ◽  
Cold Gas Dynamic Spray ◽  
Gas Dynamic Spray ◽  
Scale Deposition ◽  
Cold Gas

Cold gas dynamic spray is a relatively new coating process by which coatings can be produced without significant heating during the process. Cold gas dynamic spray is conducted by powder sprayed using supersonic gas jet, and generally called the kinetic spray or cold spray. Its low process temperature can minimize the thermal stress and also reduce the deformation of the substrate. In this study, thick or macro scale deposition was studied while most researches on cold-spray have focused on micro scale coating. Measured material properties of macro scale deposition layer showed that elastic modulus and hardness were lower and electrical resistivity was higher than those of reference substrate material. The main causes of changed material properties were investigated by FE-SEM (Field Emission Scanning Electron Microscope) and EDS (Energy Dispersive X-ray Spectrometer) data. In this result, porous micro structure generated by imperfect plastic deformation might cause decrease in elastic modulus and hardness of the deposition layer by cold spray, and oxidized Al particles increased the electrical resistivity.

Application of Electrical Resistivity Tomography and Ground Penetrating Radar to assess salinity in a coastal aquifer with tidally-driven saline recirculation cell

2020 ◽  
Author(s):  
Jesús Fernández Águila ◽  
Mark McDonnell ◽  
Raymond Flynn ◽  
Alastair Ruffell ◽  
Eric Benner ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Seawater Intrusion ◽  
Ground Penetrating Radar ◽  
Water Samples ◽  
Electrical Resistivity Tomography ◽  
High Water ◽  
Fresh Groundwater ◽  
Resistivity Tomography ◽  
Tidally Driven ◽  
Ground Penetrating

<p>Seawater intrusion is a major issue worldwide, as coastal aquifers often act as the primary source of drinking water for more than one billion people. With climate change and projected population increases in coastal areas, this problem is anticipated to become more pressing over the next decades. Effective site characterisation strategies provide a crucial component in understanding subsurface saltwater migration. Density differences cause freshwater to float on seawater creating the classical saltwater intrusion saline wedge. However, tides often control coastal groundwater dynamics causing the emergence of an upper saline recirculation cell beneath the intertidal zone (Intertidal Recirculation Cell, IRC). Here we present the application of Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) techniques to characterize the coastal sand aquifer underlying Benone Strand (Magilligan, Northern Ireland) where tides induce an IRC. The aquifer is approximately 20 m thick and rests directly on Lr. Jurassic mudstones.</p><p>2D ERT profiles were generated at Benone beach using the SYSCAL Pro 72 ERI system (Iris Instruments). Two different array configurations (Wenner-Schlumberger and dipole-dipole) were used to provide both improved horizontal and vertical resolution. Because of the homogeneity of the sand, the ERT profiles made it possible to clearly define the configuration of the IRC and the fresh groundwater discharging “tube”. The presence of the tidally-driven recirculation cell causes fresh groundwater to flow below the IRC (“discharge tube”) and discharge in the vicinity of the low water mark. ERT data suggest that the IRC has a resistivity of approximately 1 Ωm and a thickness of 8 m. Resistivity increases below the IRC, but declines moving towards the low water mark. These findings suggest a possible mixing zone between saline water and the freshwater discharge. To verify the accuracy of the resistivity values measured in the ERT profiles, water samples were collected at various distances along a perpendicular transect from the high water mark to the low water mark. The electrical conductivities of the water samples were measured and compared with the resistivities obtained in the ERT profiles using Archie's law. Similar values were obtained in both cases.</p><p>A MALÅ ground penetrating radar system, operating at 50 MHz, 100 MHz and 500 MHz, was used to collect 2D GPR profiles at Benone beach from the low tide mark to beyond the high water mark. Findings suggested that the IRC attenuated the radar signal in all cases. However, GPR profiles were crucially important to demarcate the interfaces between freshwater and saltwater near the ground surface. GPR profiles obtained using higher frequencies (500 MHz) were the most informative.</p><p>The research work carried out at Magilligan allows us to conclude that the application of ERT and GPR techniques is effective in delineating seawater intrusion in aquifers where tides create an IRC. In addition, ERT profiles very clearly identified the IRC through field measurements (which in most cases is studied through numerical models and laboratory tests).</p>

scholarly journals Change of Pore-Fracture Structure of Anthracite Modified by Electrochemical Treatment Using Micro-CT

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Xianfa Kong ◽  
Junqing Guo ◽  
Tianhe Kang
Keyword(s):  
Electrochemical Method ◽  
Electrochemical Treatment ◽  
Micro Ct ◽  
Average Pore ◽  
Fracture Structure ◽  
Electrochemical Modification ◽  
Gas Desorption ◽  
Negative Exponential ◽  
Dissolution Of Minerals ◽  
Anodic Zone

The electrochemical method can strengthen gas desorption and seepage from coal. The study on change of the pore-fracture structure of coal after electrochemical modification can help to reveal the mechanism. Anthracite was modified by the electrochemical method using our own self-developed experiment apparatus. The pore-fracture structure of modified samples was measured by micro-CT. Combined with the Matlab software, its characteristics such as pore number, porosity, and average pore diameter were analyzed. The results show that (1) the number of fractures in modified coal samples increases. The shape of new fractures in samples in the anodic and cathodic zones was irregular voids and striola, respectively. The effect of electrochemical treatment on the section of samples close to the electrode is relatively obvious. (2) With increasing pore size, the number of pores in samples changes according to negative exponential rules. After electrochemical modification, the porosity of modified samples in the anodic zone increases from 11.88% to 31.65%, and the porosity of modified samples in the cathodic zone increases from 12.13% to 36.71%. (3) The main reason for the increase in the number of pores of coal samples in the anodic and cathodic zones is the treatment of electrolytic dissolution of minerals and electrophoretic migration of charged particles, respectively.

Study on Stress of Closed Cut-Off Wall in Earth-Rock Dam Reinforcement under Different Engineering Conditions

2012 ◽  
Vol 594-597 ◽  
pp. 1969-1974 ◽  
Author(s):  
Jiang Lin Gao ◽  
Yun Xiang Chen
Keyword(s):  
Elastic Modulus ◽  
Stress State ◽  
Permeability Coefficient ◽  
Deformation Modulus ◽  
Dam Foundation ◽  
Filling Materials ◽  
The Earth ◽  
Coupled Numerical Model ◽  
Common Foundation ◽  
Wall Deformation

Closed concrete cut-off wall has been widely used in the reinforcement projects of earth-rock dam. However, the research on the cut-off wall was rare. In order to discuss the stress state of the wall under different engineering conditions, a coupled numerical model was established by considering coupled interaction, including contact between wall and dam, and coupling of stress and seepage. Taking the earth-rock dam which built on common foundation for example, the stress distribution of the wall and influencing law of different factors were mainly researched, including elastic modulus of the wall, deformation modulus of the dam filling materials, permeability coefficient of the dam foundation, etc. The conclusions had reference significance for the application and design and calculation method of concrete cut-off wall in the reinforcement projects of earth-rock dam.

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