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1
Li, Wentao, Runxiang Li, Yin Chen i Henglin Xiao. "Comparison of Two Sulfate-Bearing Soils Stabilized with Reactive Magnesia-Activated Ground Granulated Blast Furnace Slag: Swelling, Strength, and Mechanism". Buildings 13, nr 1 (13.01.2023): 230. http://dx.doi.org/10.3390/buildings13010230.
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Sulfate-bearing soils, which causes many engineering problems, e.g., cracking, collapse, and pavement layer settlement, are often encountered in the construction of pavements. Ground granulated blast furnace slag (GGBS)-magnesia (MgO) has been regarded as an effective curing agent in the treatment of sulfate-bearing soil containing gypsum. However, field sulfate-bearing soils usually include other forms of sulfates, such as sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4). Currently, few studies have investigated the effect of the type of sulfate on the properties of sulfate-bearing soil stabilized with GGBS-MgO. In this study, GGBS-MgO was used to treat Ca-sulfate-soil and Mg-sulfate-soil. Swelling, unconfined compressive strength (UCS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) tests were employed to investigate the properties of the stabilized soils. The results showed that when suitable GGBS:MgO ratios were achieved, the swelling of the two types of sulfate-bearing soils could be well suppressed. However, the trend that the swelling varied with the decrease in the GGBS:MgO ratios was opposite between the two soils. The UCS of Mg-sulfate-soils was much lower than that of the Ca-sulfate-soils after the stabilization of GGBS-MgO irrespective of the curing or soaking stage. CSH significantly occurred in Ca-sulfated soils treated by GGBS-MgO. Ettringite was not observed in the soil with GGBS-MgO = 9:1 but was observed in 6:4. Compared to Ca-sulfate-soils, MSH and less CSH were formed in Mg-sulfate-soils stabilized with GGBS-MgO, which caused the lower strength of the stabilized Mg-sulfate-soils. No ettringite was formed in such soils. Hence, the sulfate type contained in the soils had a significant effect on the swelling and strength properties of sulfate-bearing soils with GGBS-MgO, and so the sulfate needs to be identified before the soil’s stabilization.
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Kissambinova, Aizhan, Chang Seon Shon, Ayazhan Bazarbekova, Saken Sandybay, Di Chuan Zhang i Jong Ryeol Kim. "High Sulfate-Bearing Kaolin Clay Stabilization with Waste Glass Powder before and after Mellowing Process". Key Engineering Materials 920 (16.05.2022): 232–38. http://dx.doi.org/10.4028/p-2y75dh.
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Road construction on sulfate-bearing soils is a worldwide concern because it is associated with a volume swelling stability issue due to the ettringite formation. Several treatment techniques were developed to solve this problem and improve geotechnical soil properties, including using pozzolanic materials and applying the mellowing process. This research evaluated the combined effect of cement and waste glass powder (WGP) on stabilizing sulfate-bearing soil before and after the mellowing procedure. Total six mixtures were developed, which includes 4% cement, 4% cement + 2% WGP, and 4% cement + 6% WGP before and after soil mellowing. The experimental program included particle size distribution of soil and stabilizers, chemical analyses of stabilizers, soil properties, unconfined compressive strength, and three-dimensional (3-D) swelling for the high sulfate-bearing kaolin clay. The test results demonstrated that the use of WGP in soil with a high sulfate content WGP improved strength development, decreased volumetric swelling, and reduced moisture susceptibility.
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Deng, Xiao Xuan, Lei Dai i Xin Huang. "Effect of Stabilizer and Molding Technics in Chemical Engineering on the Stabilization of Sulfate Rich Soil". Advanced Materials Research 577 (październik 2012): 65–68. http://dx.doi.org/10.4028/www.scientific.net/amr.577.65.
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In chemical engineering field, ettringite (AFt) formation effect the stabilization of sulfate rich soil mixed with cementitious materials. The different stabilizer compositions and twice molding technics may avoid and repair the destruction caused by AFt with decreasing the production rate of calcium silicate hydrates(C-S-H) and eliminating the void in stabilized soils. The results show that the strength of stabilized 5% sodium sulfate bearing soils, under above methods, are not less than that of the control ones, and the specimens keep steady after soaking in 5% sodium sulfate solution for 12 weeks.
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Talluri, Nagasreenivasu, Anand J. Puppala, Bhaskar C. S. Chittoori, Ahmed H. Gaily i Pat Harris. "Stabilization of High-Sulfate Soils by Extended Mellowing". Transportation Research Record: Journal of the Transportation Research Board 2363, nr 1 (styczeń 2013): 96–104. http://dx.doi.org/10.3141/2363-11.
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The use of lime to stabilize expansive soils has been the preferred technique for many years. However, heaving and premature pavement failures in lime-treated expansive subgrades containing sulfates led to the search for alternative stabilization techniques. Of the several techniques developed, precompaction mellowing has the potential to be effective in stabilizing sulfate-bearing soils. Yet this method needs experimental evaluation. In the current study, an attempt was made to assess the stabilization effectiveness of precompaction mellowing on high-sulfate soils. For this task, six natural expansive soils from Texas, with sulfate contents varying from 200 to 44,000 ppm, were collected. Soils with low-sulfate contents were spiked with additional sulfates to make them high-sulfate soils. Basic classification and chemical tests were performed to establish the clay mineralogy of the soils. Three mellowing periods (0, 3, and 7 days) were studied. The test soils were treated with lime and allowed to mellow for the specified periods. Following the mellowing, the samples were subjected to three-dimensional tests for volumetric swell, shrinkage, and unconfined compressive strength (UCS). To study the consumptions of alumina and silica during sulfate–soil–lime reactions, reactive alumina and silica measurements were also attempted. The authors observed that shrinkage was of no concern in treated soils because the shrinkage invariably reduced with lime treatment. In four of the six soils, precompaction mellowing reduced sulfate-induced swell to a level below the natural expansive swelling. The UCS strengths of treated soils decreased slightly with mellowing. Reasons for the anomaly in UCS strengths and ineffectiveness of precompaction mellowing in two soils were explained.
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Wang, Zhongmei, Pawan Sigdel i Liangbo Hu. "Chemo-Mechanical Interactions in the Ettringite Induced Expansion of Sulfate-Bearing Soils". Geosciences 9, nr 9 (29.08.2019): 375. http://dx.doi.org/10.3390/geosciences9090375.
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Expansive sulfate-bearing soils are frequently encountered in transportation and construction practices. These soils are often treated with a lime or cement stabilizer to improve the relevant qualities. However, the reaction between sulfate and alumina in soils and calcium of lime or cement can lead to the formation of ettringite, an expansive sulfate mineral resulting in soil swelling or heaving. The underlying mechanisms often involve intricate interactions between chemical processes and mechanical responses. The present study explores a chemo–mechanical approach in an attempt to quantify several mechanisms potentially responsible for the volume expansion, including the geochemical formation of ettringite, crystallization pressure, and osmosis-induced swelling. The geochemical reaction leading to ettringite formation is examined with a specific focus on the circumstances under which it may lead to volume change. The crystallization pressure developed during the ettringite formation may also play a significant role in the soil expansion and is investigated in the present study based on thermodynamic formulations, and the resulting volume expansion is simulated. The osmosis-induced swelling is studied within the context of the chemo–mechanical framework, and its kinetics is also explored. Numerical simulations are performed in the present study to examine different scenarios driven by distinct predominant mechanisms. In particular, the interplay between ettringite formation and osmosis swelling as interpreted from some recently-reported experimental studies shows that these mechanisms can all contribute to the observed expansion processes, and overall, the modeling results are consistent with the experimental findings.
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Dalhem, Krister, Stefan Mattbäck, Anton Boman i Peter Österholm. "A simplified distillation-based sulfur speciation method for sulfidic soil materials". Bulletin of the Geological Society of Finland 93, nr 1 (13.06.2021): 19–30. http://dx.doi.org/10.17741/bgsf/93.1.002.
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Speciation of inorganic sulfur species, mainly pyrite and metastable iron sulfides by operationally defined methods, is widely used for risk assessment of acid sulfate soils by quantifying the acidity producing elements, as well as for general characterisation of marine sediments and subaqueous soils. “Traditional” sulfur speciation methods commonly use highly specialised glassware which can be cumbersome for the operator, or, require long reaction times which limit the usability of the method. We present a simplified method which has a sufficiently low limit of detection (0.002%) and quantitation (0.006%) required for the analysis of sulfidic sulfur in acid sulfate soil materials. Commercially available sulfide reagents were used for determining reproducibility and the method was assessed on natural sulfidic soil materials, including fine to coarse grained soil materials as well as sulfide bearing peat, with a large variation of metastable sulfide and pyrite content.
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M.E. Baliad. "EFFECTS OF ORGANIC AND INORGANIC NITROGEN ON THE PRODUCTIVITY OF COCONUT GROWN ON THREE IMPORTANT SOIL TYPES IN LEYTE, PHILIPPINES". CORD 9, nr 01 (1.06.1993): 34. http://dx.doi.org/10.37833/cord.v9i01.267.
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Severe nitrogen‑deficiency in unfertilized plots resulted in low bearing percentage (19.62%) of the palms. Highest bearing percentage of 68.82% was observed on palms applied with 1.5 kg ammonium sulfate per palm per year.
Application of 2 kg ammonium sulfate/palm/year resulted in most number of harvested nuts. The yields of palms applied with 1.5 kg ammonium sulfate or 0.66 kg/urea/palm/year were, however, not statistically different from the former. Similar trends in fresh meat and copra yields were observed. Copra yields were significantly higher in plots applied with inorganic N fertilizers.
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Puppala, Anand J., Nagasreenivasu Talluri i Bhaskar C. S. Chittoori. "Calcium-based stabiliser treatment of sulfate-bearing soils". Proceedings of the Institution of Civil Engineers - Ground Improvement 167, nr 3 (sierpień 2014): 162–72. http://dx.doi.org/10.1680/grim.13.00008.
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Dermatas, Dimitris. "Ettringite-Induced Swelling in Soils: State-of-the-Art". Applied Mechanics Reviews 48, nr 10 (1.10.1995): 659–73. http://dx.doi.org/10.1115/1.3005046.
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Reactions between lime, alumina released from clay during pozzolanic reactions, and sulfates present in some soils, have been responsible for the deterioration and ultimate failure, by expansion, of several lime stabilization projects, by causing the formation of the highly expansive crystalline mineral ettringite. Based on an extensive literature review, the mechanisms for these reactions were hypothesized, and a laboratory research program using both artificial and natural lime-treated soil specimens was designed and undertaken. The strength, swelling, pH, compositional, and micromorphological characteristics of the treated specimens were determined following different curing times and soaking conditions. Swell development in some of the specimens prepared, in relation with pertinent strength, pH, composition, and micromorphological data obtained, allowed the delineation of the underlying mechanisms leading to heave and deterioration. It was found that the amount of heave following ettringite hydration and growth is a function of the amount and rate of release of alumina into solution. The amount and type of sulfates present, and the amount and type of lime used are also important factors in the development of heave. Moreover, temperature and relative humidity fluctuations were also found to play an important role in the overall ettringite-related heave mechanism, as they affect reaction rates, solubilities of species, and the overall stability fields of a soil system’s components. Finally, the present study was successful in developing a soil pretreatment method that would ensure safe performance of lime-stabilization applications in sulfate-bearing soils. Pretreatment of the artificial lime-treated soil mixes with barium compounds was effective in eliminating ettringite formation. Further research is needed to assess the effectiveness and the required levels of barium pretreatment in field applications. This pretreatment method, upon appropriate modifications, could be potentially applied in other sulfate-related deterioration problems.
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Little, Dallas N., Bruce Herbert i Sachin N. Kunagalli. "Ettringite Formation in Lime-Treated Soils". Transportation Research Record: Journal of the Transportation Research Board 1936, nr 1 (styczeń 2005): 51–59. http://dx.doi.org/10.1177/0361198105193600107.
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The use of calcium-based stabilizers such as calcium oxide (lime) in sulfate-bearing clay soils has historically led to structural distress because of the formation of a mineral called ettringite and possibly thaumasite. In trying to control the damage associated with such formations, engineers have attempted to determine a threshold level of soluble sulfates–-a quantity that is relatively easy and quick to measure at which significant ettringite growth and, therefore, structural distress occurs. This is indeed a complex problem related to not only soil composition but also construction methods, availability of water, ion migration, and the ability of the void structure to accommodate the expansive mineral growth. Unfortunately, experience alone and rules-of-thumb based on experience are not sufficient to deal with this complex issue. Thermodynamic geochemical models of the lime-treated soil can be used as a first step toward establishing thresholds for problematic levels of soluble sulfates for a specific soil. A foundation for the model development is presented, and two soils are compared to illustrate their sensitivities to ettringite growth on the addition of lime. Because the model predicts ettringite growth on the basis of site-specific properties, the model can be used to assess the potential amelioration effects of soluble silica.
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He, Shi, Xinbao Yu, Aritra Banerjee i Anand J. Puppala. "Expansive Soil Treatment with Liquid Ionic Soil Stabilizer". Transportation Research Record: Journal of the Transportation Research Board 2672, nr 52 (23.08.2018): 185–94. http://dx.doi.org/10.1177/0361198118792996.
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Calcium-based stabilizers such as lime and cement control swell and shrinkage behavior and enhance strength properties for expansive soils through the formation of pozzolanic components. However, sulfate-bearing subgrade soils stabilized with calcium-based stabilizers might cause excessive swelling and shrinkage due to the formation of highly expansive minerals like ettringite and thaumasite. In this paper, one liquid ionic soil stabilizer (LISS) was evaluated as an alternative stabilizer used to control swelling and shrinkage behavior of expansive soils. A comprehensive laboratory experiment program including a linear shrinkage test, a one-dimensional swell test, and an unconfined compressive strength test, was designed and carried out on soils from Dallas, Texas before and after treatment. Three dosage levels of stabilizer and four different curing periods were investigated. Test results indicate that LISS is an effective stabilizing agent, which not only reduces swelling and soil plasticity but also increases soil strength. Furthermore, a similar type of LISS is utilized to treat the soil in Dallas via deep injection using a hydraulic pump. Field emission scanning electron microscopy results on the test soil showed that the stabilizing program is likely to work through clay flocculation and morphological variations in the clay particles.
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Bishop, J. "Reflectance Spectroscopy of Ferric Sulfate-Bearing Montmorillonites as Mars Soil Analog Materials". Icarus 117, nr 1 (wrzesień 1995): 101–19. http://dx.doi.org/10.1006/icar.1995.1145.
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Zhang, Wen-hui, Hua-wen Zheng, Jia-wei Qi i Bao-tian Wang. "Experimental Study on the Feasibility of Using Water Glass and Aluminum Sulfate to Treat Complications in High Liquid Limit Soil Subgrade". Advances in Materials Science and Engineering 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/457978.
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The feasibility of using water glass and aluminum sulfate to treat high liquid limit soil subgrade diseases is studied through laboratory experiments, and the following results were observed. After improving the high liquid limit clay with water glass and aluminum sulfate, the liquid limit decreases, the plastic limit increases, and the plasticity index decreases. Compared with untreated soil, the clay content of the improved soil decreases, while the silt and coarse contents increase. The absolute and relative expansion rates of the improved soil are both lower than those of the untreated soil. With the same number of dry and wet cycles, the decreased degrees of cohesion and internal friction angle of the improved soil are, respectively, one-half and one-third of those of the untreated soil. After three dry and wet cycles, the California bearing ratio (CBR) of the untreated soil does not meet the requirements of specifications. However, after being cured for seven days and being subjected to three dry and wet cycles, the CBR of the improved soil, with 4% water glass solution and 0.4% aluminum sulfate, meets the requirements of specifications.
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Larre, Chloé, Yann Morizet, Catherine Guillot-Deudon, Fabien Baron i Nicolas Mangold. "Quantitative Raman calibration of sulfate-bearing polymineralic mixtures: a S quantification in sedimentary rocks on Mars". Mineralogical Magazine 83, nr 1 (14.09.2018): 57–69. http://dx.doi.org/10.1180/mgm.2018.147.
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AbstractThe NASA 2020 Mars mission is a Curiosity-type rover whose objective is to improve the knowledge of the geological and climatic evolution of Mars and to collect rock samples for return to Earth. The new rover has a payload of seven instruments including the SuperCam instrument which consists of four tools including a Raman spectrometer. This Raman device will be non-destructive and will analyse the surface remotely in order to determine the mineralogy of rocks and, by extent, to detect and quantify major elements such as sulfur. Sulfur has been detected as sulfate (Ca,Mg,Fe-sulfates) in sedimentary rocks. This element is difficult to quantify using the laser ablation tool of the ChemCam instrument on-board the Curiosity rover.We propose a Raman calibration to constrain the sulfur abundance in polymineralic mixtures. We acquired Raman signatures on binary and ternary mechanical mixtures containing Ca and Mg sulfates, mixed with natural silicate minerals supposed to be relevant to basaltic-sedimentary rocks at the surface of Mars: olivine, clinopyroxene, orthopyroxene and plagioclase. Using the Voigt function to process the Raman spectra from samples extracted from our mixtures allows us to calculate the initial proportions of our preparations of Ca and Mg sulfates. From these simulations, calibration equations have been provided allowing us to determine sulfate proportions (CaSO4 and MgSO4) in a mixture with basaltic minerals. With the presented calibration, S can be quantified at a lower limit of 0.7 wt.% in Martian soil.
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Marsh, Brian H., i J. H. Grove. "Surface and Subsurface Soil Acidity: Soybean Root Response to Sulfate-Bearing Spent Lime". Soil Science Society of America Journal 56, nr 6 (listopad 1992): 1837–42. http://dx.doi.org/10.2136/sssaj1992.03615995005600060031x.
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Kowalska, Magdalena, Bartłomiej Grzesik, Zdzisław Adamczyk, Jacek Nowak i Adam Konsek. "Swelling of sulfate-bearing soil: A case study of A1 highway pavement failure". Case Studies in Construction Materials 18 (lipiec 2023): e02081. http://dx.doi.org/10.1016/j.cscm.2023.e02081.
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Seco, Andrés, Jesús María del Castillo, Céline Perlot, Sara Marcelino-Sádaba, Eduardo Prieto i Sandra Espuelas. "Experimental Study of the Valorization of Sulfate Soils for Use as Construction Material". Sustainability 14, nr 11 (28.05.2022): 6609. http://dx.doi.org/10.3390/su14116609.
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This article shows an experimental investigation carried out for the stabilization of a sulfate soil. The stabilization was carried out in two phases: the first phase was the consumption of the sulfate present in the soil through its controlled transformation into ettringite. After this, a modified soil with lower maximum density, greater optimum moisture identified via standard proctor (SP) test, no plasticity and improved unconfined compressive strength (UCS) was obtained. In the second phase, the modified soil was stabilized by the use of different additives rich in oxides of calcium or magnesium, combined with by-products or waste materials containing reactive aluminum or silicon oxides. As a result, the mechanical strength of the modified soil was improved. In this phase, a binary binder composed of a magnesium oxide product and ground granulated blast-furnace slags (GGBS) obtained the highest UCS. The binary binder composed of lime and an alumina filler formed ettringite in the treated soil. This experiment allowed for the validation of a two-phase stabilization process and the non-conventional additives used, mainly magnesium oxide and GGBS, even for high-bearing-requirement pavement layers’ construction.
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Rahmat, Mohamad Nidzam, i John M. Kinuthia. "Effects of mellowing sulfate-bearing clay soil stabilized with wastepaper sludge ash for road construction". Engineering Geology 117, nr 3-4 (luty 2011): 170–79. http://dx.doi.org/10.1016/j.enggeo.2010.10.015.
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Xu, Lina, Xu Ding, Shuang Sun, Hao Gu, Lei Niu i Yang Chen. "Experimental Study on the Influence of Snow-Melting Agents on Fiber-Reinforced Cemented Soil under Freezing-Thawing Cycles". Advances in Materials Science and Engineering 2023 (22.02.2023): 1–15. http://dx.doi.org/10.1155/2023/9766539.
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To explore the effect of snow-melting agents on the glass fiber-reinforced cemented soil under freezing-thawing cycles, three widely used snow-melting agents, including potassium acetate, magnesium chloride, and sodium sulfate, were used in this article. The effects of snow-melting agent types on the apparent damage, mass loss, and mechanical properties of fiber-reinforced cemented soil under freezing-thawing cycles were analyzed through salt freezing and unconfined compressive strength tests. The results show that the snow-melting effect of potassium acetate is the best, the snow-melting effect of magnesium chloride is the second, and the snow-melting effect of sodium sulfate is the worst. Notably, as the number of freezing-thawing cycles increases, the strength of the test block decreases to varying degrees. After the fifth freezing-thawing cycle, the strength of the block without fiber decreased by 61.30%, 70.22%, and 81.58% in clear water, potassium acetate, and magnesium chloride solution, respectively, while the test block in sodium sulfate solution lost its bearing capacity. A series of studies proved that the snow-melting agent with sodium sulfate as the main component has the most apparent erosion effect on the cemented soil, followed by magnesium chloride, and the erosion effect of potassium acetate is the weakest. The incorporation of glass fiber can effectively improve the resistance of the cemented soil under the action of various salt solution erosion and freezing-thawing coupling and has a significant effect on slowing the development of surface cracks, improving peak strength, and reducing the mass loss rate. This research will provide theoretical support for the design of subgrade and the selection of snow-melting agents in cold areas.
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Ebailila, Mansour, John Kinuthia i Jonathan Oti. "Suppression of Sulfate-Induced Expansion with Lime–Silica Fume Blends". Materials 15, nr 8 (12.04.2022): 2821. http://dx.doi.org/10.3390/ma15082821.
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Sulfate-induced expansion resulting from the formation of ettringite in sulfate-bearing soil stabilised with calcium-based stabilisers is a problematic issue with technical and economic implications. Thus, this research examines the viability of the co-addition of lime (L) and silica fume (S) at varying binder dosages (4, 6, and 10 wt%), with a view of establishing the optimum blend of L–S for suppressing the ettringite-induced expansion of artificially high sulfate-dosed soil (kaolinite-K and gypsum-G). To do so, a series of laboratory specimens, designed using different gypsum and lime concentrations, were investigated using unconfined compression strength (UCS), linear expansion, and derivative thermo-gravimetric analysis (DTG) as the main criteria for the examination. The research outcomes indicated that the increasing substitution of L with S induces a gradual reduction on the UCS and linear expansion at binder levels of 4 and 6 wt%, while its usage in a high binder level (10 wt%), can yield an expansion reduction, with no compromise on the UCS performance. Therefore, silica fume has the potential for restricting ettringite formation and suppressing the expansion, of which 3L7S is the optimum blending ratio for suppressing the expansion.
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Demas, S. Y., A. M. Hall, D. S. Fanning, M. C. Rabenhorst i E. K. Dzantor. "Acid sulfate soils in dredged materials from tidal Pocomoke Sound in Somerset County, MD, USA". Soil Research 42, nr 6 (2004): 537. http://dx.doi.org/10.1071/sr03089.
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Seepage and runoff waters from soils forming in sulfide-bearing dredge materials (SBDM) can have dramatic effects on water quality if they are placed adjacent to open water and do not have adequate containment. Soils forming in SBDM can produce large amounts of acidity upon sulfide oxidation and the oxidation and hydrolysis of released ferrous iron when they are drained or otherwise exposed to air. These soils, under certain environmental conditions, can produce low pH seepage and runoff waters containing large amounts of iron and aluminum, especially after heavy rain that follows a prolonged dry period. During the course of the soil survey update of Somerset County, Maryland (MD), USA, 2 areas of soils forming in SBDM of differing age were identified in close proximity to the sites of recent fish kills on the Pocomoke Sound in Somerset County. Both of these soil areas were initially contained by earthen berms. The dredge materials were deposited directly over the natural tidal marsh soil. Soils forming in SBDM that are approximately 60 years of age were classified as fine-silty, mixed mesic Sulfic Endoaquepts, while the second area of SBDM are 8 years of age and classified as fine-silty, mixed, mesic Typic Sulfaquepts, by Soil Taxonomy. The presence of jarosite was confirmed in both soils by X-ray diffraction, and the presence of ironstone (iron oxyhydroxides) was confirmed in both soils at the effluent discharge points. This is an indication that these soils have undergone intensive acid sulfate weathering (sulfuricization) and that they have released a large quantity of iron to waters leaving the sites. Studies have shown that the 2 mechanisms responsible for acid production from soils forming in SBDM are (i) the oxidation and hydrolysis of mobile ferrous iron; and (ii) the oxidation of the sulfur occurring in the form of pyrite. It is suggested that the resultant low pH, Fe- and Al-enriched water from these soils that entered the Pocomoke Sound may have made fish more susceptible to microbial predation by weakening mucous membranes and/or by promoting the growth of harmful cyannobacteria and flagellates. This paper reports the nature and classification of soils that developed in SBDM at 2 sites of differing age and of the possible environmental impacts of seepage and runoff from these sites entering the Pocomoke Sound.
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Ehwailat, Khaled Ibrahim Azarroug, Mohd Ashraf Mohamad Ismail i Ali Muftah Abdussalam Ezreig. "Novel Approach for Suppression of Ettringite Formation in Sulfate-Bearing Soil Using Blends of Nano-Magnesium Oxide, Ground Granulated Blast-Furnace Slag and Rice Husk Ash". Applied Sciences 11, nr 14 (19.07.2021): 6618. http://dx.doi.org/10.3390/app11146618.
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The treatment of sulfate-bearing soil with calcium-based stabilizers such as cement or lime often results in ettringite formation, consequently leading to swelling and strength deterioration. Ettringite formation has negative environmental and economic effects on various civil engineering structures. This study was conducted to investigate the use of different materials (nano–magnesium oxide (M), ground granulated blast-furnace slag (GGBS), and rice husk ash (RHA)) for gypseous soil stabilization to prevent ettringite formation. Various tests were performed, including flexural strength, unconfined compression strength, linear expansion, and microstructure analysis (SEM/EDX), on lime (L)-, (M)-, (M-RHA)-, (M-GGBS)-, and (M-GGBS-RHA)-stabilized gypseous soil samples to determine their properties. The results indicated that the swelling rates of the soil samples mixed with 20% M-RHA, M-GGBS, and M-GGBS-RHA binders were much lower (less than 0.01% of volume change) than those of the soil samples mixed with 10% and 20% lime-stabilized binders after a curing period of 90 days. Meanwhile, the strengths of the soil samples mixed with 20% of M-RHA, M-GGBS, and M-GGBS-RHA soil specimens after soaking of 90 days were obviously higher (with a range from 2.7–12.8 MPa) than those of the soil samples mixed with 20% of lime-stabilized binder. The SEM and EDX results showed no ettringite formation in the M-RHA-, M-GGBS-, and M-GGBS-RHA-stabilized soils. Overall, the test results proved the potential of M-RHA, M-GGBS, and M-GGBS-RHA as effective soil stabilizers.
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Yang, Min, Yan Xie i Ying Pang. "Durability of Lime-Fly Ash Stabilized Soil Activated by Calcined Phosphogypsum". Advanced Materials Research 168-170 (grudzień 2010): 133–38. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.133.
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Stabilized soil is widely used as road base and sub-base materials, and is sometimes used as covering for waste matter in China. In soil stabilization, the property of a locally available soil are usually modified though chemical stabilization[1]. Cement stabilization and lime stabilization are the two most commonly used methods. Lime-fly ash stabilized soil has been widely applied in road engineering due to its good integrity, great bearing capacity, high stiffness, and water-proofing quality[2-4]. One disadvantage of lime-fly ash stabilized soil is that without any additives, its inherent low initial strength makes it inappropriate for use under low-temperature conditions. Researchers have found that the pozzolanic reactivity among lime, fly ash, and soil contributes to the strength of lime-fly ash stabilized soil. To increase the initial strength of lime-fly ash stabilized soil, many approaches have been used to accelerate the pozzolanic reaction. Sulfate activation is one of the methods that has been widely investigated, specifically, Na2SO4 and CaSO4[5]. PG, another sulfate, has also been investigated. However, existing studies have limited to the investigation of the development of strength of the stabilized soil as road base and sub-base materials. The effect of PG on the durability of stabilized soil has rarely been implicated. This work aims to study the effect of thermally treated PG (400°C) on the properties of durability, in addition to other aspects, of lime-fly ash stabilized soil. Lime-fly ash stabilized soil with different proportions of calcined PG were prepared and cured at normal conditions for 7 d and 28 d. Mass loss and strength loss under different treatments were determined. X-ray diffraction(XRD) patterns and scanning electron microscopy(SEM) photos were examined to gauge whether improvements in the performances of the stabilized soil can be obtained by use of thermally treated PG.
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Piochi, Monica, Angela Mormone, Harald Strauss i Giuseppina Balassone. "The acid sulfate zone and the mineral alteration styles of the Roman Puteoli (Neapolitan area, Italy): clues on fluid fracturing progression at the Campi Flegrei volcano". Solid Earth 10, nr 6 (30.10.2019): 1809–31. http://dx.doi.org/10.5194/se-10-1809-2019.
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Abstract. Active fumarolic solfataric zones represent important structures of dormant volcanoes, but unlike emitted fluids, their mineralizations are omitted in the usual monitoring activity. This is the case of the Campi Flegrei caldera in Italy, among the most hazardous and best-monitored explosive volcanoes in the world, where the landscape of Puteoli is characterized by an acid sulfate alteration that has been active at least since Roman time. This paper provides temperature, mineralogical, textural, compositional and stable isotope data for those solfataric terrains sampled at the crater and Pisciarelli slope of the Solfatara volcano between 2013 and 2019. Temperatures vary between 40 and 95 ∘C. Minerals include alunite with grain sizes generally larger than 20 µm, alunogen, native sulfur, well-ordered kaolinite, and, common at Pisciarelli, pyrite, illite and NH4 sulfates. Sulfate terrains have higher contents of Ti, Ba, Au, As, Hg and Tl relative to their parent substrate. The Pisciarelli slope is anomalous in terms of the presence of NH4. δ34S values for sulfides and native S range between −3.00 ‰ and 0.49 ‰ and from −4.42 ‰ to 0.80 ‰, respectively. Sulfates show δ34S and δ18O values in the range of −2.78 ‰ to 2.09 ‰ and between 4.60 ‰ and 31.33 ‰, respectively. The style of mineralization and the stable isotope geochemistry do produce complex and not completely consistent classifications and genetic constraints. We merge our data with volcanological information, data from exploration drillings and geophysical results. With the conceptual model, we suggest a series of shallow and deep aquifers interconnected like “communicating vessels” through a main fault system that downthrows Solfatara with respect to Pisciarelli. Fluid outflow from the different discrete aquifers hosted in sediments – and possibly bearing organic imprints – is the main dataset that allows determination of the steam-heated environment with a supergene setting superimposed. Supergene conditions and high-sulfidation relicts, together with the narrow sulfate alteration zone buried under the youngest volcanic deposits, point to the existence of an evolving paleo-conduit. The data will contribute to monitoring and evaluating the volcanic hazards.
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Peng, Bo, Zhongchang Yang, Zhengwen Yang i Jingwen Peng. "Effects of pH and Fineness of Phosphogypsum on Mechanical Performance of Cement–Phosphogypsum-Stabilized Soil and Classification for Road-Used Phosphogypsum". Coatings 10, nr 11 (23.10.2020): 1021. http://dx.doi.org/10.3390/coatings10111021.
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This article investigates the effects of phosphogypsum (PG) pH and particle fineness on the mechanical properties of cement–PG-stabilized soil. Using solutions of calcium hydroxide (Ca(OH)2) and sulfate (H2SO4) to adjust pH value of PG from 2 to 8. The key pore size used to characterize PG fineness was determined to be 200 μm based on the Grey relational analysis (GRA), and the fineness of PG was controlled from 12.31% to 56.32% by grinding different time. Cement–PG cementitious materials (CPCM) and cement–PG-stabilized soil with different mixture ratios were formed at an optimum moisture content; following this, the unconfined compressive strength and California bearing ratio values of the samples were tested. Results show that the increased pH or the decreased fineness leads to continuous increases in the unconfined compressive strength of CPCM and cement-PG stabilized soil as well as the CBR value of cement–PG-stabilized soil. However, once PG pH value exceeded 5 or fineness was less than 20%, the mechanical properties of cement–PG-stabilized soil remained stable. A classification standard for road usage PG was established based on the analyses regarding cement-PG stabilized soil’s mechanical properties, which has great significance of selecting or disposing road-used PG.
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Li, Jie, Wancang Zhao, Hongxia Du, Yaobing Guan, Ming Ma i Heinz Rennenberg. "The symbiotic system of sulfate-reducing bacteria and clay-sized fraction of purplish soil strengthens cadmium fixation through iron-bearing minerals". Science of The Total Environment 820 (maj 2022): 153253. http://dx.doi.org/10.1016/j.scitotenv.2022.153253.
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Eluozo, Solomon Ndubuisi, i C. Nwaobakata. "Predictive models to determine the behavior of plastic and liquid limit of Lateratic soil for Raod construction at Egbema: Imo state of Nigeria". International Journal of Engineering & Technology 2, nr 1 (20.11.2012): 25. http://dx.doi.org/10.14419/ijet.v2i1.425.
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Predictive values to determine the behaviour of plastic and liquid of lateritic soil for road design and construction has been developed, this two parameters has a relationship in term of soil classification through their laboratory results, both parameters sample were subjected to through laboratory analysis for several locations, the laboratory results of both parameters were plotted to determine there behavious and limits, the results generated equations at various locations, the equations were resolved and it generated theoretical values, the model values displayed there relationship on the classification of soil for road construction. The implementation of a laboratory testing proceedure is to classify subgrade material and assess sustain properties and moisture sensitivity (heavy, collapse, softening) that can influence long-term pavement performance. Testing implementation consists of classification testing, these are (i.e., gradation analysis, Atterberg Limits and sulfate tests). Generated predictive models producing theoretical values, are engineering properties of soil testing for various parameters (i.e., swell/consolidation, R-value, unconfined compressive strength, California Bearing Ratio, and Resilient Modulus Tests). This are also design parameters that should generate predictive models that can be applied as design parameter in the study area, the study is imperative because predictive models generated and validated has ascertain proof of the workability of the models as design parameter in design of flexible pavements in the study location.
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Binal, A. "The Effects of High Alkaline Fly Ash on Strength Behaviour of a Cohesive Soil". Advances in Materials Science and Engineering 2016 (2016): 1–11. http://dx.doi.org/10.1155/2016/3048716.
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Contemporarily, there are 16 coal-burning thermal power plants currently operating in Turkey. This number is expected to rise to 46 in the future. Annually, about 15 million tons of fly ash are removed from the existing thermal power plants in Turkey, but a small proportion of it, 2%, is recyclable. Turkey’s plants are fired by lignite, producing Class C fly ash containing a high percentage of lime. Sulfate and alkali levels are also higher in Class C fly ashes. Therefore, fly ash is, commonly, unsuitable as an additive in cement or concrete in Turkey. In this study, highly alkaline fly ash obtained from the Yeniköy thermal power plants is combined with soil samples in different proportions (5%, 10%, 15%, 20%, and 25%) and changes in the geomechanical properties of Ankara clay were investigated. The effect of curing time on the physicomechanical properties of the fly ash mixed soil samples was also analyzed. The soil classification of Ankara clay changed from CH to MH due to fly ash additives. Free swelling index values showed a decrease of 92.6%. Direct shear tests on the cohesion value of Ankara clay have shown increases by multiples of 15.85 and 3.01 in internal friction angle values. The California bearing ratio has seen a more drastic increase in value (68.7 times for 25% fly ash mix).
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Hasheminassab, S., N. Daher, A. Saffari, D. Wang, B. D. Ostro i C. Sioutas. "Spatial and temporal variability of sources of ambient fine particular matter (PM<sub>2.5</sub>) in California". Atmospheric Chemistry and Physics Discussions 14, nr 14 (4.08.2014): 20045–81. http://dx.doi.org/10.5194/acpd-14-20045-2014.
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Abstract. To identify major sources of ambient fine particulate matter (PM2.5, dp<2.5 μm) and quantify their contributions in the state of California, positive matrix factorization (PMF) receptor model was applied on speciation trends network (STN) data, collected between 2002 and 2007 at 8 distinct sampling locations, including El Cajon, Rubidoux, Los Angeles, Simi Valley, Bakersfield, Fresno, San Jose, and Sacramento. Between five to nine sources of fine PM were identified at each sampling site, several of which were common among multiple locations. Secondary aerosols, including secondary ammonium nitrate and ammonium sulfate, were the most abundant contributor to ambient PM2.5 at all sampling sites, except for San Jose, with an annual average cumulative contribution of 26 to 63%, across the state. On an annual average basis, vehicular emissions (including both diesel and gasoline vehicles) were the largest primary source of fine PM at all sampling sites in southern California (17–18% of total mass), whereas in Fresno and San Jose, biomass burning was the most dominant primary contributor to ambient PM2.5 (27 and 35% of total mass, respectively), in general agreement with the results of previous source apportionment studies in California. In Bakersfield and Sacramento, vehicular emissions and biomass burning displayed relatively equal annual contributions to ambient PM2.5 mass (12 and 25%, respectively). Other commonly identified sources at all sites included aged and fresh sea salt as well as soil, which contributed to 0.5–13%, 2–27%, and 1–19% of the total mass, respectively, across all sites and seasons. In addition, few minor sources were exclusively identified at some of the sites (e.g. chlorine sources, sulfate-bearing road dust, and different types of industrial emissions). These sources overall accounted for a small fraction of the total PM mass across the sampling locations (1 to 15%, on an annual average basis).
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Hasheminassab, S., N. Daher, A. Saffari, D. Wang, B. D. Ostro i C. Sioutas. "Spatial and temporal variability of sources of ambient fine particulate matter (PM<sub>2.5</sub>) in California". Atmospheric Chemistry and Physics 14, nr 22 (18.11.2014): 12085–97. http://dx.doi.org/10.5194/acp-14-12085-2014.
Pełny tekst źródłaStreszczenie:
Abstract. To identify major sources of ambient fine particulate matter (PM2.5, dp < 2.5 μm) and quantify their contributions in the state of California, a positive matrix factorization (PMF) receptor model was applied on Speciation Trends Network (STN) data, collected between 2002 and 2007 at eight distinct sampling locations, including El Cajon, Rubidoux, Los Angeles, Simi Valley, Bakersfield, Fresno, San Jose, and Sacramento. Between five to nine sources of fine PM were identified at each sampling site, several of which were common among multiple locations. Secondary aerosols, including secondary ammonium nitrate and ammonium sulfate, were the most abundant contributor to ambient PM2.5 mass at all sampling sites, except for San Jose, with an annual average cumulative contribution of 26 to 63%, across the state. On an annual average basis, vehicular emissions (including both diesel and gasoline vehicles) were the largest primary source of fine PM at all sampling sites in southern California (17–18% of total mass), whereas in Fresno and San Jose, biomass burning was the most dominant primary contributor to ambient PM2.5 (27 and 35% of total mass, respectively), in general agreement with the results of previous source apportionment studies in California. In Bakersfield and Sacramento, vehicular emissions and biomass burning displayed relatively equal annual contributions to ambient PM2.5 mass (12 and 25%, respectively). Other commonly identified sources at all sites included aged and fresh sea salt and soil, which contributed to 0.5–13%, 2–27%, and 1–19% of the total mass, respectively, across all sites and seasons. In addition, a few minor sources were identified exclusively at some of the sites (e.g., chlorine sources, sulfate-bearing road dust, and different types of industrial emissions). These sources overall accounted for a small fraction of the total PM mass across the sampling locations (1 to 15%, on an annual average basis).
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Keating, David H. "Sinorhizobium meliloti SyrA Mediates the Transcriptional Regulation of Genes Involved in Lipopolysaccharide Sulfation and Exopolysaccharide Biosynthesis". Journal of Bacteriology 189, nr 6 (5.01.2007): 2510–20. http://dx.doi.org/10.1128/jb.01803-06.
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ABSTRACT Sinorhizobium meliloti is a gram-negative soil bacterium found either in free-living form or as a nitrogen-fixing endosymbiont of leguminous plants such as Medicago sativa (alfalfa). S. meliloti synthesizes an unusual sulfate-modified form of lipopolysaccharide (LPS). A recent study reported the identification of a gene, lpsS, which encodes an LPS sulfotransferase activity in S. meliloti. Mutants bearing a disrupted version of lpsS exhibit an altered symbiosis, in that they elicit more nodules than wild type. However, under free-living conditions, the lpsS mutant displayed no change in LPS sulfation. These data suggest that the expression of lpsS is differentially regulated, such that it is transcriptionally repressed during free-living conditions but upregulated during symbiosis. Here, I show that the expression of lpsS is upregulated in strains that constitutively express the symbiotic regulator SyrA. SyrA is a small protein that lacks an apparent DNA binding domain and is predicted to be located in the cytoplasmic membrane yet is sufficient to upregulate lpsS transcription. Furthermore, SyrA can mediate the transcriptional upregulation of exo genes involved in the biosynthesis of the symbiotic exopolysaccharide succinoglycan. The SyrA-mediated transcriptional upregulation of lpsS and exo transcription is blocked in mutants harboring a mutation in chvI, which encodes the response regulator of a conserved two-component system. Thus, SyrA likely acts indirectly to promote transcriptional upregulation of lpsS and exo genes through a mechanism that requires the ExoS/ChvI two-component system.
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Kota, Prakash B. V. S., Darren Hazlett i Les Perrin. "Sulfate-Bearing Soils: Problems with Calcium-Based Stabilizers". Transportation Research Record: Journal of the Transportation Research Board 1546, nr 1 (styczeń 1996): 62–69. http://dx.doi.org/10.1177/0361198196154600107.
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Several roads, airfield pavements, and parking lots in Texas and other states in the western United States have suffered severe pavement damage due to expansive minerals formed from the reactions of calcium-based materials used to stabilize sulfate-bearing soils. Remediation costs for projects that suffer sulfate-induced heave damage are very high, because often the entire pavement may have to be removed and reconstructed. Observations from several projects are described to illustrate the phenomenon of sulfate-induced heave and the current methods to predict the problem. Two recent projects described include one using cement as a replacement for lime and a second using a double application of lime. The discussion also includes limitations of the present methods for determining the so-called soluble sulfate levels in soils. The practice of a double application of lime and several other alternative methods and their limitations are discussed. Although research has clearly identified the expansive minerals as being calcium bearing, no published investigations of non-calcium-based stabilizers that could effectively stabilize sulfate-bearing soils were found.
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Harris, Pat, Omar Harvey, Leah Jackson, Meagan DePugh i Anand Puppala. "Killing the Ettringite Reaction in Sulfate-Bearing Soils". Transportation Research Record: Journal of the Transportation Research Board 2462, nr 1 (styczeń 2014): 109–16. http://dx.doi.org/10.3141/2462-13.
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Hunter, Dal. "Lime‐Induced Heave in Sulfate‐Bearing Clay Soils". Journal of Geotechnical Engineering 114, nr 2 (luty 1988): 150–67. http://dx.doi.org/10.1061/(asce)0733-9410(1988)114:2(150).
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Buttress, A. J., J. A. Grenfell i G. D. Airey. "Accelerated swell testing of artificial sulfate bearing lime stabilised cohesive soils". Materials and Structures 48, nr 11 (28.09.2014): 3635–55. http://dx.doi.org/10.1617/s11527-014-0428-y.
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Puppala, Anand J., Rupesh Kadam, Raja S. Madhyannapu i Laureano R. Hoyos. "Small-Strain Shear Moduli of Chemically Stabilized Sulfate-Bearing Cohesive Soils". Journal of Geotechnical and Geoenvironmental Engineering 132, nr 3 (marzec 2006): 322–36. http://dx.doi.org/10.1061/(asce)1090-0241(2006)132:3(322).
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Géring, Léa, Moritz Kirsch, Samuel Thiele, Andréa De Lima Ribeiro, Richard Gloaguen i Jens Gutzmer. "Spectral characterisation of hydrothermal alteration associated with sediment-hosted Cu–Ag mineralisation in the central European Kupferschiefer". Solid Earth 14, nr 4 (27.04.2023): 463–84. http://dx.doi.org/10.5194/se-14-463-2023.
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Abstract. The analysis of hydrothermal alteration in exploration drill cores allows for fluid–rock interaction processes to be traced, for fluid flow paths to be identified, and thus for vectors in mineral systems to be determined. Hyperspectral imaging techniques are increasingly being employed to fill the scale gap between lab-based petrographic or geochemical analyses and the typical size of exploration targets. Hyperspectral imaging permits the rapid, cost-efficient, and continuous characterisation of alteration mineralogy and texture along entire drill cores, with a spatial sampling of a few millimetres. In this contribution, we present the results of an exploratory study on three mineralised drill cores from the Spremberg–Graustein Kupferschiefer-type Cu–Ag deposit in the Lusatia region of Germany. We demonstrate that hyperspectral imaging is well-suited to recognising and tracking the effects of hydrothermal alteration associated with strata-bound hydrothermal mineralisation. Micro X-ray fluorescence spectrometry was used to corroborate the alteration mineral assemblages identified in hyperspectral data acquired in the visible, near- (400 to 970 nm), shortwave (970 to 2500 nm), mid-wave (2700 to 5300 nm), and longwave infrared (7700 to 12 300 nm). We identified two main shortcomings of the technique, namely the overlapping of some mineral features (e.g. carbonate and illite absorption in the shortwave infrared) and the darkness of the organic-matter-rich dolostones and shales that results in low reflectance. Nevertheless, spectral features associated with iron oxide, kaolinite, sulfate, and carbonates were successfully identified and mapped. We identified different markers of hydrothermal alteration spatially associated with or stratigraphically adjacent to Cu–Ag mineralisation. Importantly, we can clearly distinguish two mineralogically distinct styles of alteration (hematite and ferroan carbonate) that bracket high-grade Cu–Ag mineralisation. Intensive hydrothermal alteration is characterised by the occurrence of well-crystallised kaolinite in the sandstone units immediately below the Kupferschiefer horizon sensu stricto. Proximal Fe-carbonate and kaolinite alteration have not previously been documented for the high-grade Cu–Ag deposits of the central European Kupferschiefer, whereas hematite alteration is well-known in Kupferschiefer-type ore deposits. The latter marks the flow path of oxidising, metal-bearing hydrothermal fluids towards the site of hydrothermal sulfide mineralisation. In contrast, ferroan carbonate alteration in carbonate rocks located above the main mineralised zone is interpreted as a mark of hydrothermal fluid discharge from the mineralising system. Although this study is limited to a small number of drill cores, our results suggest that hyperspectral imaging techniques may be used to identify vectors towards high-grade Cu–Ag mineralisation in Kupferschiefer-type mineral systems.
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Mitchell, M. R., R. E. Link, Pranshoo Solanki i Musharraf M. Zaman. "Laboratory Performance Evaluation of Subgrade Soils Stabilized with Sulfate-Bearing Cementitious Additives". Journal of Testing and Evaluation 38, nr 1 (2010): 102378. http://dx.doi.org/10.1520/jte102378.
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Cao, X. M., J. Cai, S. B. Li, H. Zhang, Z. Q. Lu i X. P. Hu. "Fusarium solani and Fusarium oxysporum Associated with Root Rot of Glycyrrhiza uralensis in China". Plant Disease 97, nr 11 (listopad 2013): 1514. http://dx.doi.org/10.1094/pdis-12-12-1111-pdn.
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Liquorice (root of Glycyrrhiza uralensis Fisch.) is an important Chinese traditional medicine for many ailments (4). From 2002, severe outbreaks of root rot occurring on cultivated G. uralensis plants in Ningxia, China, have affected the yield and quality of liquorice and been considered as a major threat to commercial production of liquorice. Approximately 30% of the plants die from this disease in Ningxia every year. The disease, mainly affecting 2- to 4-year-old G. uralensis seedlings, begins with brown rot of root tips or lateral roots followed by internal decay of taproots during June to August every year. The infected plants are wilted with chlorotic foliage and easily pulled up from the soil. Root rot is clearly visible as a severe brown discoloration of vascular tissue along taproots. In severe cases, white mycelia are clearly visible on the surface of diseased roots and roots are decomposed. Isolations from diseased roots were made on potato dextrose agar (PDA) amended with streptomycin sulfate. Isolates (n = 78) were recovered from symptomatic roots (n = 105) and pure cultures were established by the single spore method. The two most frequently isolated fungi were transferred to potato sucrose agar and identified as Fusarium solani (61.5%) and F. oxysporum (30.8%) (1). The monophialides bearing microconidia of F. solani are long when compared to those of F. oxysporum. Genomic DNA of strains F. solani G013 and F. oxysporum FLR were extracted from mycelia with the cetyltrimethylammonium bromide (CTAB) method. Primers EF1-728F and EF1-986R were used to amplify the translation elongation factor-1α (TEF-1α) gene (2). The TEF-1α sequences of F. solani G013 (GenBank Accession No. AB777258) and F. oxysporum FLR (AB777257) shared 99 and 100% similarity with F. solani isolate NRRL52790 and F. oxysporum isolate NRRL 38328, respectively. Pathogenicity tests with one representative isolate of each species were conducted in the greenhouse on 1-month-old potted G. uralensis seedlings (12 plants per treatment). Isolates of the tested fungi were transferred to PDA and incubated in darkness at 24 ± 1°C for 7 days. Plant taproots about 5 cm below the soil surface were wounded with a sterile needle and five 5-mm-diameter fungal disks on the margin of colony were taken and firmly placed on the wounded location of each taproot with tinfoil; wounded taproots of seedlings inoculated with sterile PDA disks were used as controls (3). Root rot was assessed 2 months after inoculation. F. solani G013 and F. oxysporum FLR produced root rot symptoms on inoculated plants that were the same as those observed in field plants, and the fungi were reisolated from roots with typical symptoms. Control plants inoculated with sterile PDA disks remained asymptomatic, and no pathogen was isolated from them. To our knowledge, this is the first report of root rot caused by F. solani and F. oxysporum on G. uralensis in China. Effective control strategies are needed to minimize losses. References: (1) C. Booth. The Genus Fusarium. Commonwealth Mycological Institute, Farnham Royal, 1971. (2) I. Carbone and L. M. Kohn. Mycologia 91:553, 1999. (3) M. Guo et al. Plant Dis. 96:909, 2012. (4) T. Wu et al. Am. Assoc. Pharm. Sci. J. 13:1, 2011.
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Cooper, C. "Spectroscopy of Loose and Cemented Sulfate-Bearing Soils: Implications for Duricrust on Mars". Icarus 158, nr 1 (lipiec 2002): 42–55. http://dx.doi.org/10.1006/icar.2002.6874.
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Little, Dallas, i Syam Nair. "Validation of Sensitivity of Sulfate-Bearing Soils to Ettringite Growth by Differential Scanning Calorimetry". Transportation Research Record: Journal of the Transportation Research Board 2104, nr 1 (styczeń 2009): 63–70. http://dx.doi.org/10.3141/2104-07.
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Al-Dakheeli, Hussein, Rifat Bulut, G. Scott Garland i Christopher R. Clarke. "Utilization of Blast-Furnace Slag as a Standalone Stabilizer for High Sulfate-Bearing Soils". Journal of Materials in Civil Engineering 33, nr 10 (październik 2021): 04021257. http://dx.doi.org/10.1061/(asce)mt.1943-5533.0003880.
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Mertely, J., T. Seijo i N. Peres. "First Report of Macrophomina phaseolina Causing a Crown Rot of Strawberry in Florida". Plant Disease 89, nr 4 (kwiecień 2005): 434. http://dx.doi.org/10.1094/pd-89-0434a.
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Strawberry (Fragaria × ananassa Duchesne) is produced as an annual winter crop in raised, plastic-mulched beds on 2,800 ha in west central Florida. In December 2001, a grower submitted collapsed and dying strawberry plants from a commercial field to the University of Florida in Dover. The cut crowns of affected plants revealed dark brown necrotic areas on the margins and along the woody vascular ring. Macrophomina phaseolina was isolated from pieces of infected tissue cut aseptically from the crowns and placed on a medium containing 12 g of Difco potato dextrose broth, 17 g of Bacto agar, 250 mg of ampicillin, and 100 mg of streptomycin sulfate per liter of water. The fungus produced numerous, dark, oblong sclerotia in the isolation medium after 4 to 5 days incubation at 24°C under constant fluorescent lighting. In 10-day-old cultures, sclerotia ranged in size from 55 to 190 μm long by 50 to 135 μm wide (average 105 × 74 μm). Ostiolate pycnidia bearing relatively large, broadly ellipsoidal, hyaline conidia occasionally developed on the host tissue after 8 to 10 days of incubation (2). During the 2003-2004 season, M. phaseolina was isolated from dying strawberry plants taken from the original field and two additional farms. Affected plants were often found along field margins or other areas inadequately fumigated with methyl bromide. Two single-spore isolates from different fields were tested for pathogenicity on nursery runner plants (cv. Strawberry Festival) grown for 4 weeks in the greenhouse on artificial potting soil. The fungal isolates were grown on corn meal agar at 24°C for 4 days and allowed to colonize sterile wooden toothpicks placed on the medium for an additional 5 days. Prior to use, the toothpicks were sterilized by autoclaving twice in deionized water and a third time in V8 juice. Six plants were inoculated with each isolate by inserting a colonized toothpick into each crown. Sterile, V8-infused toothpicks were inserted into the crowns of corresponding control plants. The plants were incubated in a greenhouse in a randomized complete block design with two replicates of three plants each. After 3 days, 33 to 100% of the inoculated plants developed wilting in one or more leaves. All inoculated plants collapsed or died within 2 weeks of inoculation, while the control plants remained healthy during the observation period. The pathogen was readily reisolated from inoculated plants. Charcoal rot disease caused by M. phaseolina has been reported on strawberry in France, India, and Illinois (2,3). To our knowledge, this is the first report from Florida. M. phaseolina may be an emerging threat as the Florida strawberry industry transitions from methyl bromide to other fumigants in 2005. References: (1) J. Maas. Macrophomina leaf blight and dry crown rot. Page 26 in: Compendium of Strawberry Diseases. 2nd ed. J. L. Maas, ed. The American Phytopathological Society, St. Paul, MN, 1998. (2) G. S. Smith and T. D. Wyllie. Charcoal rot. Pages 29–31 in: Compendium of Soybean Diseases. G. L. Hartman et al., eds. 4th ed. The American Phytopathological Society, St. Paul, MN. 1999. (3) B. Tweedy et al. Plant Dis. Rep. 42:107, 1958.
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N. Thomas, Andrew, Elisabeth Eiche, Jörg Göttlicher, Ralph Steininger, Liane G. Benning, Helen M. Freeman, Knud Dideriksen i Thomas Neumann. "Products of Hexavalent Chromium Reduction by Green Rust Sodium Sulfate and Associated Reaction Mechanisms". Soil Systems 2, nr 4 (29.10.2018): 58. http://dx.doi.org/10.3390/soilsystems2040058.
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The efficacy of in vitro Cr(VI) reduction by green rust sulfate suggests that this mineral is potentially useful for remediation of Cr-contaminated groundwater. Previous investigations studied this reaction but did not sufficiently characterize the intermediates and end products at chromate (CrO42−) concentrations typical of contaminant plumes, hindering identification of the dominant reaction mechanisms under these conditions. In this study, batch reactions at varying chromate concentrations and suspension densities were performed and the intermediate and final products of this reaction were analyzed using X-ray absorption spectroscopy and electron microscopy. This reaction produces particles that maintain the initial hexagonal morphology of green rust but have been topotactically transformed into a poorly crystalline Fe(III) oxyhydroxysulfate and are coated by a Cr (oxy) hydroxide layer that results from chromate reduction at the surface. Recent studies of the behavior of Cr(III) (oxy) hydroxides in soils have revealed that reductive transformation of CrO42− is reversible in the presence of Mn(IV) oxides, limiting the applicability of green rust for Cr remediation in some soils. The linkage of Cr redox speciation to existing Fe and Mn biogeochemical cycles in soils implies that modification of green rust particles to produce an insoluble, Cr(III)-bearing Fe oxide product may increase the efficacy of this technique.
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Celik, Ece, i Zalihe Nalbantoglu. "Effects of ground granulated blastfurnace slag (GGBS) on the swelling properties of lime-stabilized sulfate-bearing soils". Engineering Geology 163 (sierpień 2013): 20–25. http://dx.doi.org/10.1016/j.enggeo.2013.05.016.
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Chowdhury, Md Abu Raihan, i David M. Singer. "Trace Metal Enrichment in the Colloidal Fraction in Soils Developing on Abandoned Mine Spoils". Minerals 12, nr 10 (14.10.2022): 1290. http://dx.doi.org/10.3390/min12101290.
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The release of colloid-bound trace metals from abandoned coal mine spoils can potentially be a significant source of contamination during weathering. We examined the size-dependent enrichment of trace metals in mine spoil samples using centrifugation and acid extraction to compare metal loading in the bulk and colloid fractions. A combination of X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and focused ion beam (FIB) sectioning of selected colloids for transmission electron microscopy (TEM) analyses was used to determine the morphology and elemental and mineral composition at the micro- and nanoscales. In contrast to bulk soils, primary Fe-sulfides (up to 11%) and secondary Fe(III)-bearing phases (up to 5%) were a significant portion of the colloid mineralogy. Secondary Fe-(hydro)oxides and (hydroxy)sulfates were enriched with Mn, Ni, Cu, and Zn, and these metals showed stronger correlations with Fe in the colloid fraction (R2 of 0.58, 0.77, 0.94, and 0.81, respectively) than in the bulk fraction (R2 of 0.40, 0.09, 0.84, and 0.62, respectively), indicating that Fe-bearing colloids are likely major trace-metal-bearing phases. The results from this study will help to design better remediation projects for abandoned mine spoils to better account for a potentially underappreciated mode of contaminant transport.
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Toivonen, Janne, Richard Hudd, Miriam Nystrand i Peter Österholm. "Climatic effects on water quality in areas with acid sulfate soils with commensurable consequences on the reproduction of burbot (Lota lota L.)". Environmental Geochemistry and Health 42, nr 10 (17.03.2020): 3141–56. http://dx.doi.org/10.1007/s10653-020-00550-1.
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Abstract Due to discharge from acid sulfate (a.s.) soils, watercourses and coastal areas in the Gulf of Bothnia are periodically heavily acidified with high concentrations of potentially toxic metals. Data on water quality from 2005 to 2014 in an embanked lake, an estuary of four rivers in western Finland, showed repeated events with acidic water (pH < 5.5) with high concentrations of Al. Size fractionation and species modeling of Al showed that a significant part of the Al occurred as highly toxic small-size fractions (dissolved < 1 kDa and colloidal 1 kDa—0.45 µm) as free ions and complexed to sulfate. The larval abundance of the burbot (Lota lota L.) was shown to be sensitive to acidity during the wintertime spawning migration and spawning. Bearing in mind the importance of estuaries of the northern Baltic Sea as spawning and nursery areas of fish, the reoccurring failure in the reproduction of fish may cause a more serious threat for the lake and adjacent coastal fish stocks than the spectacular, but less frequent, mass kills of adult fish. This demonstrates the close relationship between climate, hydrology, water geochemistry and the aquatic coastal ecosystem in areas affected by a.s. soils. As the current forecast of climate chance indicates warmer winters with more continuous runoff, the effects can become even more prominent. This study also shows that the annual larvae abundance of burbot may be used as a bioindicator and an instrument for the fisheries for obtaining more comprehensive knowledge of the ecological effects of acidic metal discharge from a.s. soils.
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Frost, Ray L., i Eloise C. Keeffe. "Raman spectroscopic study of the sulfite-bearing minerals scotlandite, hannebachite and orschallite: implications for the desulfation of soils". Journal of Raman Spectroscopy 40, nr 3 (marzec 2009): 244–48. http://dx.doi.org/10.1002/jrs.2089.
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Wells, M. Lenny. "Pecan Response to Nitrogen Fertilizer Source". HortScience 56, nr 3 (marzec 2021): 368–73. http://dx.doi.org/10.21273/hortsci15620-20.
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A better understanding of the efficacy of various nitrogen (N) forms on pecan tree production would help growers make more sound decisions regarding the fertilization of their orchards. The following treatments were evaluated for their effect on pecan leaf tissue nutrient concentration, leaf chlorophyll index, trunk circumference growth, pecan yield, nut weight, percent kernel, pecan tree yield efficiency, and alternate bearing: 1) ammonium nitrate (AN; 34N–0P–0K) at 1.8 kg N per tree (AN1.8); 2) AN (34N–0P–0K) at 3.6 kg N per tree (AN3.6); 3) ammonium sulfate (AS) at 1.8 kg N per tree (AS1.8); 4) AS at 3.6 kg N per tree (AS3.6); 5) urea at 1.8 kg N per tree (U1.8); 6) urea at 3.6 kg per tree (U3.6); and 7) untreated control (C). Leaf elemental tissue analysis, pecan tree trunk growth, pecan yield, quality, and alternate bearing intensity (I) suggest that pecan trees are unaffected by differences in the fertilizer sources used in this study on the acidic soils of the Southeastern U.S. Coastal Plain. N rate also had little influence on measured variables. Based on these results and, perhaps more directly, upon agronomic N use efficiency (AEN), it appears that pecans can be more efficiently fertilized at N rates of 108 kg N/ha compared with 215 kg N/ha under Southeastern U.S. Coastal Plain conditions regardless of N source.
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Sutter, B., J. B. Dalton, S. A. Ewing, R. Amundson i C. P. McKay. "Terrestrial analogs for interpretation of infrared spectra from the Martian surface and subsurface: Sulfate, nitrate, carbonate, and phyllosilicate-bearing Atacama Desert soils". Journal of Geophysical Research: Biogeosciences 112, G4 (4.10.2007): n/a. http://dx.doi.org/10.1029/2006jg000313.
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