Search results for: permeability of sand

Authors: Galo D. Soria, Jenny S. Casame, Eddy F. Pazmino

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In Ecuador, mining operations have significantly impacted water sources. Artisanal mining extensively relies in mercury amalgamation. Mercury is a neurotoxic substance even at low concentrations. The objective of this investigation is to exploit Hg-removal capacity of sulfur-limonene polysulfide (SLP), which is a low-cost polymer, in order to prepare granular media (sand) coated with SLP to be used in laboratory scale column-filtration systems. Preliminary results achieved 85% removal of Hg⁺⁺ from synthetic effluents using 20-cm length and 5-cm diameter columns at 119m/day average pore water velocity. During elution of the column, the SLP-coated sand indicated that Hg⁺⁺ is permanently fixed to the collector surface, in contrast, uncoated sand showed reversible retention in Hg⁺⁺ in the solid phase. Injection of 50 pore volumes decreased Hg⁺⁺ removal to 46%. Ongoing work has been focused in optimizing the synthesis of SLP and the polymer content in the porous media coating process to improve Hg⁺⁺ removal and extend the lifetime of the column-filter.

Keywords: column-filter, mercury, mining, polysulfide, water treatment

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Authors: Muhammad Rizwan Akram, Saim Raza, Hamza Hanif Chauhan

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This paper describes the aim of research to evaluate the performance of ordinary Portland concretes containing cement replacement materials in both binary and ternary system. Blocks of concrete were prepared to have a constant water-binder ratio of 0.30. The test variables included the type and the amount of the supplementary cementious materials (SCMs) such as class of Silica Fume (SF) and ground granulated blast furnace slag (GGBS). Portland cement was replaced with Silica Fume (SF) upto 7.5% and GGBS up to a level of 50%. Then physical properties are assessed from the compressive strength and permeability tests.

Keywords: silica fume, GGBS, compressive strength, permeability

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Authors: Sam S. Hashemi

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The breakage of bonding between sand particles and their dislodgment from the borehole wall are among the main factors resulting in a borehole failure in poorly cemented granular formations. The grain debonding usually precedes the borehole failure and it can be considered as a sign that the onset of the borehole collapse is imminent. Detecting the bonding breakage point and introducing an appropriate failure criterion will play an important role in borehole stability analysis. To study the influence of different factors on the initiation of sand bonding breakage at the borehole wall, a series of laboratory tests was designed and conducted on poorly cemented sand samples. The total absorbed strain energy per volume of material up to the point of the observed particle debonding was computed. The results indicated that the particle bonding breakage point at the borehole wall was reached both before and after the peak strength of the thick-walled hollow cylinder specimens depending on the stress path and cement content. Three different cement contents and two borehole sizes were investigated to study the influence of the bonding strength and scale on the particle dislodgment. Test results showed that the stress path has a significant influence on the onset of the sand bonding breakage. It was shown that for various stress paths, there is a near linear relationship between the absorbed energy and the normal effective mean stress.

Keywords: borehole stability, experimental studies, poorly cemented sands, total absorbed strain energy

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Authors: M. A. Gad, A. Z. Al-Herrawy

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Microsporidia comprises various pathogenic species can infect humans by means of water. Moreover, chlorine disinfection of drinking-water has limitations against this protozoan pathogen. A total of 48 water samples were collected from two drinking water treatment plants having two different filtration systems (slow sand filter and rapid sand filter) during one year period. Samples were collected from inlet and outlet of each plant. Samples were separately filtrated through nitrocellulose membrane (142 mm, 0.45 µm), then eluted and centrifuged. The obtained pellet from each sample was subjected to DNA extraction, then, amplification using genus-specific primer for microsporidia. Each microsporidia-PCR positive sample was performed by two species specific primers for Enterocytozoon bieneusi and Encephalitozoon intestinalis. The results of the present study showed that the percentage of removal for microsporidia through different treatment processes reached its highest rate in the station using slow sand filters (100%), while the removal by rapid sand filter system was 81.8%. Statistically, the two different drinking water treatment plants (slow and rapid) had significant effect for removal of microsporidia. Molecular identification of microsporidia-PCR positive samples using two different primers for Enterocytozoon bieneusi and Encephalitozoon intestinalis showed the presence of the two pervious species in the inlet water of the two stations, while Encephalitozoon intestinalis was detected in the outlet water only. In conclusion, the appearance of virulent microsporidia in treated drinking water may cause potential health threat.

Keywords: removal, efficacy, microsporidia, drinking water treatment plants, PCR

Procedia PDF Downloads 179

Authors: K. Arroudj, M. Lanez, M. N. Oudjit

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The introduction of siliceous mineral additions in cement production allows, in addition to the ecological and economic gain, improvement of concrete performance. This improvement is mainly due to the fixing of Portlandite, released during the hydration of cement, by fine siliceous, forming denser calcium silicate hydrates and therefore a more compact cementitious matrix. This research is part of the valuation of the Dune Sand (DS) in the cement industry in Algeria. The high silica content of DS motivated us to study its effect, at ground state, on the properties of mortars in fresh and hardened state. For this purpose, cement pastes and mortars based on ground dune sand (fine quartz) has been analyzed with a replacement to cement of 15%, 20% and 25%. This substitution has reduced the amount of heat of hydration and avoids any risk of initial cracking. In addition, the grinding of the dune sand provides amorphous thin populations adsorbed at the surface of the crystal particles of quartz. Which gives to ground quartz pozzolanic character. This character results an improvement of mechanical strength of mortar (66 MPa in the presence of 25% of ground quartz).

Keywords: mineralogical structure, pozzolanic reactivity, Quartz, mechanical strength

Procedia PDF Downloads 256

Authors: P. Chultheera, T. Rirksomboon, S. Kulprathipanja, C. Liu, W. Chinsirikul, N. Kerddonfag

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Gas separation by selective transport through polymeric membranes is one of the rapid growing branches of membrane technology. However, the tradeoff between the permeability and selectivity is one of the critical challenges encountered by pure polymer membranes, which in turn limits their large-scale application. To enhance gas separation performances, mixed matrix membranes (MMMs) have been developed. In this study, MMMs were prepared by a solution-coating method and tested for CO₂/CH₄ separation through permeability and selectivity using a membrane testing unit at room temperature and a pressure of 100 psig. The fabricated MMMs were composed of silicone rubber dispersed with the activated carbon individually absorbed with polyethylene glycol (PEG) as a liquid additive. PEG emulsified silicone rubber MMMs showed superior gas separation on cellulose acetate membrane with both high permeability and selectivity compared with silicone rubber membrane and alone support membrane. However, the MMMs performed limited stability resulting from the undesirable PEG leakage. To stabilize the MMMs, PEG was then incorporated into activated carbon by adsorption. It was found that the incorporation of solid and liquid was effective to improve the separation performance of MMMs.

Keywords: mixed matrix membrane, membrane, CO₂/CH₄ separation, activated carbon

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Authors: Zou Xuan, Liu Hongchen

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The ideal dentin desensitizing agent should not only have good biological safety, simple clinical operation mode, the superior treatment effect, but also should have a durable effect to resist the oral environmental temperature change and oral mechanical abrasion, so as to achieve a persistent desensitization effect. Also, when using desensitizing agent to prevent the post-operative hypersensitivity, we should not only prevent it from affecting crowns’ retention, but must understand its effects on bond strength of dentin adhesives. There are various of desensitizers and dentin adhesives in clinical treatment. They have different chemical or physical properties. Whether the use of desensitizing agent would affect the bond strength of dentin adhesives still need further research. In this in vitro study, we built the hypersensitive dentin model and post-operative dentin model, to evaluate the sealing effects and durability on exposed tubule by three different dentin desensitizers and to evaluate the sealing effects and the bond strength of dentin adhesives after using three different dentin desensitizers on post-operative dentin. The result of this study could provide some important references for clinical use of dentin desensitizing agent. 1. As to the three desensitizers, the hypersensitive dentin model was built to evaluate their sealing effects on exposed tubule by SEM observation and dentin permeability analysis. All of them could significantly reduce the dentin permeability. 2. Test specimens of three groups treated by desensitizers were subjected to aging treatment with 5000 times thermal cycling and toothbrush abrasion, and then dentin permeability was measured to evaluate the sealing durability of these three desensitizers on exposed tubule. The sealing durability of three groups were different. 3. The post-operative dentin model was built to evaluate the sealing effects of the three desensitizers on post-operative dentin by SEM and methylene blue. All of three desensitizers could reduce the dentin permeability significantly. 4. The influences of three desensitizers on the bonding efficiency of total-etch and self-etch adhesives were evaluated with the micro-tensile bond strength study and bond interface morphology observation. The dentin bond strength for Green or group was significantly lower than the other two groups (P<0.05).

Keywords: dentin, desensitizer, dentin permeability, thermal cycling, micro-tensile bond strength

Procedia PDF Downloads 371

Authors: M. N. Yahaya, K. A. Salako, U. Z. Magawata

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Vertical electrical sounding (VES) method was used to investigate the groundwater potential at the southern part of Gulumbe district, Kebbi State, north-western part of Nigeria. The study was carried out with the aim of determining the subsurface layer’s parameters (resistivity and thickness) and uses the same to characterize the groundwater potential of the study area. The Schlumberger configuration was used for data acquisition. A total number of thirty-three (33) sounding points (VES) were surveyed over six profiles. The software IPI2WIN was used to obtain n-layered geo-electric sections. The geo-electric section drawn from the results of the interpretation revealed that three subsurface layers could be delineated, which comprise of top soil, sand, sandstone, coarse sand, limestone, and gravelly sand. The results of the resistivity sounding were correlated with the lithological logs of nearby boreholes that expose cross-section geologic units around the study area. We found out that the area is dominated by three subsurface layers. The coarse sand layers constituted the aquifer zones in the majority of sounding stations. Thus, this present study concluded that the depth of any borehole in the study area should be located between the depth of 18.5 to 39 m. The study further classified the VES points penetrated based on their conductivity content as highly suitable, suitable, moderately suitably, and poor zones for groundwater exploration. Hence, from this research, we recommended that boreholes can be sited in high conductivity zones across VES 2, 11, 13, 16, 20, 21, 27, and 33, respectively.

Keywords: vertical electrical sounding, resistivity, geo-electric, resistivity, aquifer and groundwater

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Authors: Sanjeev Mukherjee, Satyendra Mittal

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This paper presents the experimental investigations on the behaviour of a group of single, double and triple helical screw anchors embedded vertically at the same level in sand. The tests were carried out on one, two, three and four numbers of anchors in sand for different depths of embedment keeping shallow and deep mode of behaviour in mind. The testing program included 48 tests conducted on three model anchors installed in sand whose density kept constant throughout the tests. It was observed that the ultimate pullout load varied significantly with the installation depth of the anchor and the number of anchors. The apparent coefficient of friction (f*) between anchor and soil was also calculated based on the test results. It was found that the apparent coefficient of friction varies between 1.02 and 4.76 for 1, 2, 3, and 4 numbers of single, double and triple helical screw anchors. Plate load tests conducted on model soil showed that the value of ф increases from 35o for virgin soil to 48o for soil with four double screw helical anchors. The graphs of ultimate pullout capacity of a group of two, three and four no. of anchors with respect to one anchor were plotted and design equations have been proposed correlating them. Based on these findings, it has been concluded that the load-displacement relationships for all groups can be reduced to a common curve. A 3-D finite element model, PLAXIS, was used to confirm the results obtained from laboratory tests and the agreement is excellent.

Keywords: apparent coefficient of friction, helical screw anchor, installation depth, plate load test

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Authors: Rudi Ryacudu, Edi Artono, Gema Wahyudi Purnama

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Oil and gas consumption in Indonesia is currently on the rise due to its nation economic improvement. Unfortunately, Indonesia’s domestic oil production cannot meet it’s own consumption and Indonesia has lost its status as Oil and Gas exporter. Even worse, our conventional oil and gas reserve is declining. Unwilling to give up, the government of Indonesia has taken measures to invite investors to invest in domestic oil and gas exploration to find new potential reserve and ultimately increase production. Yet, it has not bear any fruit. Indonesia has taken steps now to explore new unconventional oil and gas play including Shale Gas, Shale Oil and Tight Sands to increase domestic production. These new plays require definite parameters to differentiate each concept. The purpose of this paper is to provide ways in defining unconventional hydrocarbon reservoir parameters in Shale Gas, Shale Oil and Tight Sands. The parameters would serve as an initial baseline for users to perform analysis of unconventional hydrocarbon plays. Some of the on going concerns or question to be answered in regards to unconventional hydrocarbon plays includes: 1. The TOC number, 2. Has it been well “cooked” and become a hydrocarbon, 3. What are the permeability and the porosity values, 4. Does it need a stimulation, 5. Does it has pores, and 6. Does it have sufficient thickness. In contrast with the common oil and gas conventional play, Shale Play assumes that hydrocarbon is retained and trapped in area with very low permeability. In most places in Indonesia, hydrocarbon migrates from source rock to reservoir. From this case, we could derive a theory that Kitchen and Source Rock are located right below the reservoir. It is the starting point for user or engineer to construct basin definition in relation with the tectonic play and depositional environment. Shale Play concept requires definition of characteristic, description and reservoir identification to discover reservoir that is technically and economically possible to develop. These are the steps users and engineers has to do to perform Shale Play: a. Calculate TOC and perform mineralogy analysis using water saturation and porosity value. b. Reconstruct basin that accumulate hydrocarbon c. Brittlenes Index calculated form petrophysical and distributed based on seismic multi attributes d. Integrated natural fracture analysis e. Best location to place a well.

Keywords: unconventional hydrocarbon, shale gas, shale oil tight sand reservoir parameters, shale play

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Authors: Abdel Moktader A. El Sayed, Nahla A. El Sayed

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Fifty-one sandstone core samples were obtained from the wadi Saal area. They belong to the Pre-Cenomanian age. These samples were subjected to various laboratory measurements such as density, porosity, permeability, electrical resistivity, grain size analysis and ultrasonic wave velocity. The parameters describing reservoir properties are outlined. The packing index, reservoir quality index, flow zone indicator and pore throat radius (R35 and R36) were calculated. The obtained interrelationships among these parameters allow improving petrophysical knowledge about the Pre-Cenomanian reservoir information. The obtained rock physics models could be employed with some precautions to the subsurface existences of the Pre-Cenomanian sandstone reservoirs, especially in the surrounding areas.

Keywords: resevoir sandstone, Egypt, Sinai, permeability

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Authors: Khalifa Abdunaser

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This study investigated the effects of oil contamination due to pro-duced water leaks that created lakes decades ago, as well as the extent of its im-pact on altering the geotechnical characteristics of the soil, which could act as a barrier to groundwater access The concentration of total petroleum hydrocarbons (TPH), which is the main component in the contaminated soil, was measured using a variety of analyses. Additionally, some extensive laboratory tests were performed to examine the effects on the soil's geotechnical properties, including particle size distribution, shear strength, consistency limits, specific gravity, and permeability coefficient. A clear decrease in TPH concentration was observed with increasing depth, and it is expected to end within only a few meters. It was found that there is a signifi-cant effect of this pollutant on the size of the soil particles, which led to them be-coming coarser than the uncontaminated soil particles. Moreover, it causes a de-crease in fluid and plastic boundaries, as well as an increase in cohesion between soil particles. However, the angle of internal friction decreases with the increase in the content of petroleum hydrocarbons in the soil samples. It came to light that determining the permeability coefficient as one of the physical characteristics of the most important factors responsible for the passage of pollutants in the groundwater, as it showed an obvious reduction in the permeability, which is the main reason dealt as an obstacle to the arrival of oil pollutants to the groundwater.

Keywords: TPH, specific gravity, oil lake, Libya

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Authors: Xiaoyu Li, Wenchuan Ding, Yujia Yia

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As the nanoscale zinc oxide particles (nano-ZnO) accumulate in the landfill, nano-ZnO will enter the landfill leachate and come into contact with the heavy metal ions in leachate, which will change their transport process in the landfill and, furthermore, affect each other's environmental fate and toxicity. In this study, we explored the transport of co-existing nano-ZnO, Cu(II) and Cr(VI) ions by column experiments under different stages of landfill leachate conditions (flow rate, pH, ionic strength, humic acid). The results show that Cu(II) inhibits the transport of nano-ZnO in the quartz sand column by increasing the surface potential of nano-ZnO, and nano-ZnO increases the retention of Cu(II) in the quartz sand column by adsorbing Cu(II) ions. Cr(VI) promotes the transport of nano-ZnO in the quartz sand column by neutralizing the surface potential of the nano-ZnO which reduces electrostatic attraction between nZnO and quartz sand, but the nano-ZnO has no effect on the transport of Cr(VI). The nature of landfill leachates such as flow rate, pH, ionic strength (IS) and humic acid (HA) has a certain effect on the transport of coexisting nano-ZnO and heavy metal ions. For leachate containing Cu(II) and Cr(VI) ions, at the initial stage of landfilling, the pH of leachate is acidic, ionic strength value is high, the humic acid concentration is low, and the transportability of nano-ZnO is weak. As the landfill age increased, the pH value in the leachate gradually increases, when the ions are raised to alkaline, these ions are trending to precipitated or adsorbed to the solid wastes in landfill, which resulting in low IS value of leachate. At the same time, more refractory organic matter gradually increases such as HA, which provides repulsive steric effects, so the nano-ZnO is more likely to migrate. Overall, the Cr(VI) can promote the transport of nano-ZnO more than Cu(II).

Keywords: heavy metal ions, landfill leachate, nano-ZnO, transport

Procedia PDF Downloads 113

Authors: Setya Winarno

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Due to abundant Merapi volcanic sand in Yogyakarta City, many local people have utilized it for mass production of concrete blocks through mini plants although their products are low in quality. This paper presents a practice model for quality improvement in this situation in order to supply the current customer interest in good quality of construction material. The method of this research was to investigate a techno economic evaluation through laboratory test and interview. Samples of twenty existing concrete blocks made by local people had only 19.4 kg/cm2 in average compression strength which was lower than the minimum Indonesian standard of 25 kg/cm2. Through repeat testing in laboratory for fulfilling the standard, the concrete mix design of water cement ratio should not be more than 0.64 by weight basis. The proportion of sand as aggregate content should not be more than 9 parts to 1 part by volume of Portland cement. Considering the production cost, the basic price was Rp 1,820 for each concrete block, comparing to Rp 2,000 as a normal competitive market price. At last, the model describes (a) maximum water cement ratio is 0.64, (b) maximum proportion of sand and cement is 1:9, (c) the basic price is about Rp. 1,820.00 and (d) strategies to win the competitive market on mass production of concrete blocks are focus in quality, building relationships with consumer, rapid respond to customer need, continuous innovation by product diversification, promotion in social media, and strict financial management.

Keywords: concrete block, good quality, improvement model, diversification

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Authors: Abel S. Huaynacho, Yoni D. Huaynacho

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The improvement of procedure test ASTM D1556, plays an important role in the developing of testing in field to obtain a higher quality of data QA/QC. The traditional process takes a considerable amount of time for only one test. Even making various testing are tasks repeating and it takes a long time to obtain better results. Moreover, if the adequate tools the help these testing are not properly managed, the improvement in the development for various testing could be stooped. This paper presents an optimized process for various testing ASTM D1556 which uses an initial standard process to another one the uses a simpler and improved management tools.

Keywords: cone sand test, density bulk, ASTM D1556, QA/QC

Procedia PDF Downloads 108

Authors: Bouziane Mohamed Tewfik

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In order to improve the understanding of the influence of rainfall intensity on infiltration and deformation behaviour of unsaturated soil slopes, numerical 2D analyses are carried out by a three phase elasto-viscoplastic seepage-deformation coupled method. From the numerical results, it is shown that regardless of the saturated permeability of the soil slope, the increase in the pore water pressure (reduction in suction) during rainfall infiltration is localized close to the slope surface. In addition, the generation of the pore water pressure and the lateral displacement are mainly controlled by the ratio of the rainfall intensity to the saturated permeability of the soil.

Keywords: unsaturated soil, slope stability, rainfall infiltration, numerical analysis

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Authors: Krishna Kumar Singh, Praveen Jain

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The collection of storm water runoff and forcing it into the groundwater is the need of the hour to sustain the ground water table. However, the runoff entraps various types of sediments and other floating objects whose removal are essential to avoid pollution of ground water and blocking of pores of aquifer. However, it requires regular cleaning and maintenance due to the problem of clogging. To evaluate the performance of filter system consisting of coarse sand (CS), gravel (G) and pebble (P) layers, a laboratory experiment was conducted in a rectangular column. The effect of variable thickness of CS, G and P layers of the filtration unit of the recharge shaft on the recharge rate and the sediment concentration of effluent water were evaluated. Medium sand (MS) of three particle sizes, viz. 0.150–0.300 mm (T1), 0.300–0.425 mm (T2) and 0.425–0.600 mm of thickness 25 cm, 30 cm, and 35 cm respectively in the top layer of the filter system and having seven influent sediment concentrations of 250–3,000 mg/l were used for the experimental study. The performance was evaluated in terms of recharge rates and clogging time. The results indicated that 100 % suspended solids were entrapped in the upper 10 cm layer of MS, the recharge rates declined sharply for influent concentrations of more than 1,000 mg/l. All treatments with a higher thickness of MS media indicated recharge rate slightly more than that of all treatment with a lower thickness of MS media respectively. The performance of storm water infiltration systems was highly dependent on the formation of a clogging layer at the filter. An empirical relationship has been derived between recharge rates, inflow sediment load, size of MS and thickness of MS with using MLR.

Keywords: groundwater, medium sand-mixed storm water filter, inflow sediment load

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Authors: R. Ziaie Moayed, E. Khavaninzadeh, M. Ghorbani Tochaee

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Direct shear test is widely used in soil mechanics experiment to determine the shear strength parameters of granular soils. For analysis of soil stability problems such as bearing capacity, slope stability and lateral pressure on soil retaining structures, the shear strength parameters must be known well. In the present study, shear strength parameters are determined in silty-sand mixtures. Direct shear tests are performed on 161 Firoozkooh sand with different silt content at a relative density of 70% in three vertical stress of 100, 150, and 200 kPa. Wet tamping method is used for soil sample preparation, and the results include diagrams of shear stress versus shear deformation and sample height changes against shear deformation. Accordingly, in different silt percent, the shear strength parameters of the soil such as internal friction angle and dilation angle are calculated and compared. According to the results, when the sample contains up to 10% silt, peak shear strength and internal friction angle have an upward trend. However, if the sample contains 10% to 50% of silt a downward trend is seen in peak shear strength and internal friction angle.

Keywords: shear strength parameters, direct shear test, silty sand, shear stress, shear deformation

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Authors: Jongho Park, Junwon Lee, Byeonghyun Choi, Kicheol Lee, Dongwook Kim

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The typically-used oil sand plant foundations are driven pile or drilled shaft. With more strict environmental regulations world widely, it became more important to completely remove the foundation during the stage of plant demolition. However, it is difficult to remove driven piles or drilled shafts that are installed at a deeper and stronger depth to gain more bearing pile capacity. The helical pile can be easily removed after its use and recycled; therefore it is suitable for oil sand plant foundation. This study analyzes the behavior of helical piles in sands. Axial pile load tests were carried out the varying spacing of helix plates (helices), rotation speed and weight of axial loading during pile installation. From the experiments, optimal helix plate spacing, rotation speed, axial loading during installation were determined. In addition, the behavior of helical pile groups was examined varying pile spacing. Finally, the behavior of single helical piles and that of group helical piles were compared.

Keywords: oil sand plant, pile load test, helical pile, group helical pile, behavior

Procedia PDF Downloads 135

Authors: Icaro V. Soares, Guilherme L. F. Brandao, Ursula D. C. Resende, Glaucio L. Siqueira

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Electrical energy can be wirelessly transmitted through resonant coupled coils that operate in the near-field region. Once in this region, the field has evanescent character, the efficiency of Resonant Wireless Power Transfer (RWPT) systems decreases proportionally with the inverse cube of distance between the transmitter and receiver coils. The commercially available RWPT systems are restricted to short and mid-range applications in which the distance between coils is lesser or equal to the coil size. An alternative to overcome this limitation is applying metamaterial structures to enhance the coupling between coils, thus reducing the field decay along the distance between them. Metamaterials can be conceived as composite materials with periodic or non-periodic structure whose unconventional electromagnetic behaviour is due to its unit cell disposition and chemical composition. This new kind of material has been used in frequency selective surfaces, invisibility cloaks, leaky-wave antennas, among other applications. However, for RWPT it is mainly applied as superlenses which are lenses that can overcome the optical limitation and are made of left-handed media, that is, a medium with negative magnetic permeability and electric permittivity. As RWPT systems usually operate at wavelengths of hundreds of meters, the metamaterial unit cell size is much smaller than the wavelength. In this case, electric and magnetic field are decoupled, therefore the double negative condition for superlenses are not required and the negative magnetic permeability is enough to produce an artificial magnetic medium. In this work, the influence of the magnetic permeability of a metamaterial slab inserted between two loosely coupled coils is studied in order to find the condition that leads to the maximum transmission efficiency. The metamaterial used is formed by a subwavelength unit cell that consist of a capacitor-loaded split ring with an inner spiral that is designed and optimized using the software Computer Simulation Technology. The unit cell permeability is experimentally characterized by the ratio of the transmission parameters between coils measured with and without the presence of the metamaterial slab. Early measurements results show that the transmission coefficient at the resonant frequency after the inclusion of the metamaterial is about three times higher than with just the two coils, which confirms the enhancement that this structure brings to RWPT systems.

Keywords: electromagnetic lens, loosely coupled coils, magnetic permeability, metamaterials, resonant wireless power transfer, subwavelength unit cells

Procedia PDF Downloads 125

Authors: Luis E. Zapata, Sergio Ruiz, María F. Mantilla, Jhon A. Villamizar

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Sand as fine aggregate for concrete production needs a feasible substitute due to several environmental issues. In this work, a study of the behavior of self-compacting concrete mixtures under replacement of sand by iron slag from 0.0% to 50.0% of weight and variations of water/cementitious material ratio between 0.3 and 0.5 is presented. Control fresh state tests of Slump flow, T500, J-ring and L-box were determined. In the hardened state, compressive strength was determined and optimization from response surface analysis was performed. The study of the variables in the hardened state was developed based on inferential statistical analyses using central composite design methodology and posterior analyses of variance (ANOVA). An increase in the compressive strength up to 50% higher than control mixtures at 7, 14, and 28 days of maturity was the most relevant result regarding the presence of iron slag as replacement of natural sand. Considering the obtained result, it is possible to infer that iron slag is an acceptable alternative replacement material of the natural fine aggregate to be used in structural concrete.

Keywords: ANOVA, iron slag, response surface analysis, self-compacting concrete

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Authors: Andrew Rylance, Anna Spenceley

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An evaluation was undertaken to understand opportunities for stimulating local enterprise development within the tourism supply chain, linked to a private game reserve in South Africa, the Sabi Sand Game Reserve, which neighbors the Kruger National Park. The study focused on understanding the market demand for local products and services from commercial lodges, and the current local supply from enterprises and entrepreneurs in local communities. This article quantifies the value of current procurement spend by lodges on local products and services and estimates their potential future expenditure. The study matches these responses with the availability of products and services in the neighboring communities. It also provides insights into relationships between private lodges, game reserves and local communities in South Africa. It concurs with previous research on tourism supply chains in rural South Africa, and also makes recommendations for the development of local businesses with higher technical capacity development.

Keywords: tourism, communities, business development, South Africa, Sabi Sand Game Reserve, market study, supply study

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Authors: Mohammed Almograbi

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Libya is one of the largest producers of dates from date palm, generating about 60000 tonnes of date palm seeds (DPS) annually. This large amount of seeds led to studies into the possible use as aggregates in lightweight concrete for some special structures. The utilization of DPS as aggregate in concrete provides a good solution as alternative aggregate to the stone aggregate. It has been recognized that, DPS can be used as coarse aggregate in structural lightweight concrete industry. For any structure member, the durability is one of the most important considerations during its service life. This paper presents the durability properties of DPS concrete. These include the water permeability, water absorption, sorptivity and chloride penetration. The test results obtained were comparable to the conventional lightweight concrete.

Keywords: date palm seeds, lightweight concrete, durability, sustainability, permeability of concrete, water absorption of concrete, sorptivity of concrete

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Authors: Faizan Hassan, Seema Kumari, V. P. Singh, Pradeep Das, Diwakar Singh Dinesh

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Phlebotomus argentipes is an established vector for Visceral Leishmaniasis in Indian subcontinent. Laboratory colonization of Sand flies is imperative in research on vectors, which requires a proper diet for their larvae and adult growth that ultimately affects their survival and fecundity. In most of the laboratories, adult Sand flies are reared on rabbit blood feeding/artificial blood feeding and their larvae on fine grinded rabbit faeces as a sole source of food. Rabbit faeces are unhygienic, difficult to handle, high mites infestation as well as owing to bad odour which creates menacing to human users ranging from respiratory problems to eye infection and most importantly it does not full fill all the nutrients required for proper growth and development. It is generally observed that the adult emergence is very low in comparison to egg hatched, which may be due to insufficient food nutrients provided to growing larvae. To check the role of food nutrients on larvae survival and adult emergence, a high protein rich artificial diet for sand fly larvae were used in this study. The composition of artificial diet to be tested includes fine grinded (9 gm each) Rice, Pea nuts & Soyabean balls. These three food ingredients are rich source of all essential amino acids along with carbohydrate and minerals which is essential for proper metabolism and growth. In this study artificial food was found significantly more effective for larval development and adult emergence than rabbit faeces alone (P value >0.05). The weight of individual larvae was also found higher in test pots than the control. This study suggest that protein plays an important role in insect larvae development and adding carbohydrate will also enhances the fecundity of insects larvae.

Keywords: artificial food, nutrients, Phlebotomus argentipes, sand fly

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Authors: Sathwik Sarvadevabhatla Kasyap, Kostas Senetakis

Abstract:

The mechanical behavior of geological materials is very complex, and this complexity is related to the discrete nature of soils and rocks. Characteristics of a material at the grain scale such as particle size and shape, surface roughness and morphology, and particle contact interface are critical to evaluate and better understand the behavior of discrete materials. This study investigates experimentally the micro-mechanical behavior of quartz sand grains with emphasis on the influence of the presence of microparticles in their contact region. The outputs of the study provide some fundamental insights on the contact mechanics behavior of artificially coated grains and can provide useful input parameters in the discrete element modeling (DEM) of soils. In nature, the contact interfaces between real soil grains are commonly observed with microparticles. This is usually the case of sand-silt and sand-clay mixtures, where the finer particles may create a coating on the surface of the coarser grains, altering in this way the micro-, and thus the macro-scale response of geological materials. In this study, the micro-mechanical behavior of Leighton Buzzard Sand (LBS) quartz grains, with interference of different microparticles at their contact interfaces is studied in the laboratory using an advanced custom-built inter-particle loading apparatus. Special techniques were adopted to develop the coating on the surfaces of the quartz sand grains so that to establish repeatability of the coating technique. The characterization of the microstructure of coated particles on their surfaces was based on element composition analyses, microscopic images, surface roughness measurements, and single particle crushing strength tests. The mechanical responses such as normal and tangential load – displacement behavior, tangential stiffness behavior, and normal contact behavior under cyclic loading were studied. The behavior of coated LBS particles is compared among different classes of them and with pure LBS (i.e. surface cleaned to remove any microparticles). The damage on the surface of the particles was analyzed using microscopic images. Extended displacements in both normal and tangential directions were observed for coated LBS particles due to the plastic nature of the coating material and this varied with the variation of the amount of coating. The tangential displacement required to reach steady state was delayed due to the presence of microparticles in the contact region of grains under shearing. Increased tangential loads and coefficient of friction were observed for the coated grains in comparison to the uncoated quartz grains.

Keywords: contact interface, microparticles, micro-mechanical behavior, quartz sand

Procedia PDF Downloads 173

Authors: Kyong-Ku Yun, Seung-Yeon Han, Kyeo-Re Lee

Abstract:

Silica fume which is a super-fine byproduct of ferrosilicon or silicon metal has a filling effect on micro-air voids or a transition zone in a hardened cement paste by appropriate mixing, placement, and curing. It, also, has a Pozzolan reaction which enhances the interior density of the hydrated cement paste through a formation of calcium silicate hydroxide. When substituting cement with silica fume, it improves water tightness and durability by filling effect and Pozzolan reaction. However, it needs high range water reducer or super-plasticizer to distribute silica fume into a concrete because of its finesses and high specific surface area. In order to distribute into concrete evenly, cement manufacturers make a pre-blended cement of silica fume and provide to a market. However, a special mixing procedures and another transportation charge another cost and this result in a high price of pre-blended cement of silica fume. The purpose of this dissertation was to investigate the dispersion of silica fume by air slurry and its effect on the mechanical properties of at ready-mixed concrete. The results are as follows: A dispersion effect of silica fume was measured from an analysis of standard deviation for compressive strength test results. It showed that the standard deviation decreased as the air bubble content increased, which means that the dispersion became better as the air bubble content increased. The test result of rapid chloride permeability test showed that permeability resistance increased as the percentages of silica fume increased, but the permeability resistance decreased as the quantity of mixing air bubble increased. The image analysis showed that a spacing factor decreased and a specific surface area increased as the quantity of mixing air bubble increased.

Keywords: cellular sprayed concrete, silica fume, deviation, permeability

Procedia PDF Downloads 115

Authors: Roman Knizek, Denisa Knizkova, Vladimir Bajzik

Abstract:

Nowadays there are countless kinds of bedsheets or mattress covers for little children which should stop any liquid getting into the mattress. It is quite easy to wash the cover of the mattress, but it is almost impossible to clean the body of a mattress which is made of latex foam, wool or synthetic materials. Children bedsheets or mattress covers are often made with plastic coating which is not steam or air permeable and therefore is not very hygienic. This is our goal: by laminating a nanofiber membrane to a suitable bedsheet textile material, we can create a bedsheet which is waterproof but at the same time steam permeable and also partially breathable, thanks to the membrane. For the same reason, nanofiber membranes are widely used in outdoor clothing. The comfort properties and durability of the new nano-membrane bedsheet were studied. The following comfort properties were investigated: steam permeability - measured in accordance with Standard ISO 11902 hydrostatic resistances - measured in accordance with Standard ISO 811 and air permeability - measured in accordance with Standard ISO 9237. The durability or more precisely the wash resistance of the nano-membrane bedsheet was also measured by submitting the sheet to 30 washing cycles. The result of our work is a children's bedsheet with a nano-membrane. The nano-membrane is made of polyurethane to keep maximum flexibility and elasticity which are essential for this product. The comfort properties of this new bedsheet are very good especially its steam permeability and hydrostatic resistance.

Keywords: bed sheet, hydrostatic resistance, nanofiber membrane, water vapour permeable

Procedia PDF Downloads 188

Authors: Ahmed M. Al-Mahbashi, Mosleh A. Al-Shamrani, Muawia Dafalla

Abstract:

Mixtures of sand and clay are frequently used to serve for specific purposes in several engineering practices. In environmental engineering, liner layers and cover layers are common for controlling waste disposal facilities. These layers are exposed to moisture and temperature fluctuation specially when existing in unsaturated condition. The relationship between soil suction and water content for these materials is essential for understanding their unsaturated behavior and properties such as retention capacity and unsaturated follow (hydraulic conductivity). This study is aimed at investigating retention capacity for two sand-natural expansive clay mixtures (15% (C15) and 30% (C30) expansive clay) at two ambient temperatures within the range of 5 -50 °C. Soil water retention curves (SWRC) for these materials were determined at these two ambient temperatures using different salt solutions for a wide range of suction (up to 200MPa). The results indicate that retention capacity of C15 mixture underwent significant changes due to temperature variations. This effect tends to be less visible when the clay fraction is doubled (C30). In addition, the overall volume change is marginally affected by high temperature within the range considered in this study.

Keywords: soil water retention curve, sand-expansive clay liner, suction, temperature

Procedia PDF Downloads 111

Authors: Waseim Ragab Azzam Ahmed Mohamed Nasr, Aalaa Ibrahim Khater

Abstract:

Torsional loads from offshore wind turbines, waves, wind, earthquakes, ship collisions in the maritime environment, and electrical transmission towers might affect the pile foundations. Torsional loads can also be caused by the axial load from the sustaining structures. The paper introduces the finned pile, an alternative method of pile modification. The effects of torsional loads were investigated through a series of experimental tests aimed at improving the torsional capacity of a single pile in the sand (where sand was utilized in a state of medium density (Dr = 50%), with or without fins. In these tests, the fins' length, width, form, and number were varied to see how these attributes affected the maximum torsional capacity of the piles. We have noticed the torsion-rotation reaction. The findings demonstrated that the fins improve the maximum torsional capacity of the piles. It was demonstrated that a length of 0.6 times the embedded pile's length and a width equivalent to the pile's diameter constitute the optimal fin geometry. For the conventional pile and the finned pile, the maximum torsional capacities were determined to be 4.12 N.m. and 7.36 N.m., respectively. When subjected to torsional loads, the fins' presence enhanced the piles' maximum torsional capacity by almost 79%.

Keywords: clean sand, finned piles, model tests, torsional load

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Authors: Bhrugesh Radadiya, Jaydeep Shah

Abstract:

In Indian foundry industry, there is a need of defect free casting with minimum production cost in short lead time. Casting defect is a very large issue in foundry shop which increases the rejection rate of casting and wastage of materials. The various parameters influences on casting process such as mold machine related parameters, green sand related parameters, cast metal related parameters, mold related parameters and shake out related parameters. The mold related parameters are most influences on casting defects in sand casting process. This paper review the casting produced by foundry with shrinkage and blow holes as a major defects was analyzed and identified that mold related parameters such as mold temperature, pouring temperature and runner size were not properly set in sand casting process. These parameters were optimized using different optimization techniques such as Taguchi method, Response surface methodology, Genetic algorithm and Teaching-learning based optimization algorithm. Finally, concluded that a Teaching-learning based optimization algorithm give better result than other optimization techniques.

Keywords: casting defects, genetic algorithm, parametric optimization, Taguchi method, TLBO algorithm

Procedia PDF Downloads 703