Browsing by Subject "Mineralogy"

Now showing 1 - 7 of 7
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    A case study of crushing resistance of Anatolian sands at lower and higher density
    (2008) Erzin Y.; Yilmaz I.
    Particle breakage occurs when the stresses imposed on soil particles exceed their strength. In order to determine the crushing resistance, Anatolian sands were collected from three different locations in Turkey. Mineralogical, particle shape and size characteristics were first determined by laboratory testing and compaction and triaxial tests then undertaken. Particle breakage factors were calculated from the initial and final gradations of the samples. It was noted that the sample containing a third calcite experienced higher particle breakage. © Springer-Verlag 2007.
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    Suitability of the methylene blue test for surface area, cation exchange capacity and swell potential determination of clayey soils
    (2008) Yukselen Y.; Kaya A.
    Application of the methylene blue test methods in determining soil properties, including specific surface area (SSA), cation exchange capacity (CEC), swell index, and swell potential are investigated on clayey soil samples with widely different mineralogy. The results indicate that the MB methods yield accurate prediction of some soil index properties, and they are easy to apply with simple test equipment. The results also show that the testing methods can be applied for soils that have widely different mineralogy. External and internal surface areas of soils can be measured by the MB adsorption methods. Effect of particle size on the MB surface area measurement accuracy was also studied using samples passing 0.425 mm (No. 40) and 0.075 mm (No. 200) sieves. The results show that there is no significant difference in the amount of absorbed methylene blue of the soil samples passing the No. 40 and No. 200 sieves. The test results also indicate that the MB-CEC values are generally lower than those obtained by the ammonium acetate method. The correlation coefficient between the MB-CEC and NH4-Na results is 0.88 indicating that MB can be used effectively to measure CEC of soils. The results also show that swell index and swell potential of the soils can be estimated with MB methods accurately, economically and readily. Significant relationship is observed between the swelling potential and MBV (methylene blue value) for a wide range of soils. A new classification for swelling soils is proposed using MBV. © 2008 Elsevier B.V.
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    Method dependency of relationships between specific surface area and soil physicochemical properties
    (2010) Yukselen-Aksoy Y.; Kaya A.
    It is postulated that the behavior of fine-grained soils may be explained by the relationship between surface area and other geotechnical properties. To this end, there are several studies correlating geotechnical indexes with specific surface area (SSA). However, there is no universally accepted specific surface area determining method as several methods are available. Depending on the method employed, the measured specific surface area may show variations for a given soil. This is because the predictive power of each method depends on the type of minerals and organic matter that are present in the soil. Thus, different SSA determination methods yield widely different estimates of index properties and regression equations. To examine the role of method on SSA of soils, the SSAs of 32 soils with different mineralogies were determined using BET-N2, EGME, MB-titration, and MB-spot test methods. The measured SSA of soils was correlated with their respective geotechnical index properties. Further, the data obtained in this study and those reported by previous researchers were compared. The results suggest that correlations between geotechnical index properties and SSA using different methods may not be comparable. Accurate prediction, however, is provided only if the relationship is calibrated using soils having similar physical and chemical characters. © 2010 Elsevier B.V.
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    Predicting soil swelling behaviour from specific surface area
    (2010) Yukselen-Aksoy Y.; Kaya A.
    Some geotechnical index properties, such as the liquid limit, plasticity index, clay content and cation exchange capacity, have been used to predict the swelling potential of soils. However, a literature review indicates that prediction of the swelling potential of soils using these index properties is not completely successful. At the same time, the methods used to determine swelling potential are time-consuming. Thus researchers have been investigating other methods that can predict the swelling potential of soils readily and accurately. To this end, in this study the BET (Brunauer, Emmett and Teller equation)-N2 adsorption, ethylene glycol monoethyl ether (EGME) and methylene blue (MB) measured specific surface areas (SSA) are correlated with the swell index and modified free swell index of soils. The SSA and swell index of 16 remoulded and 15 undisturbed soils consisting of a wide range of mineralogy were determined. Results indicate that the correlation between the SSA and the swelling behaviour of the clayey soils examined is significant. A linear relationship is observed between the swell index, Cs, and the MB SSA: the swell index of the soils increases as the SSA increases. The correlation coefficient between the SSA and the modified free swell index (MFSI) is 0.93, indicating that the MB SSA does exert a significant influence on the swelling behaviour of clayey soils. Based on the test results obtained, a new swelling potential classification is proposed.
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    Investigation of in vitro mineralization of silicate-based 45S5 and 13-93 bioactive glasses in artificial saliva for dental applications
    (Elsevier Ltd, 2017) Deliormanlı A.M.
    Bioactive glasses are important class of materials that have a wide range of applications in tissue engineering and dentistry. In dental tissue engineering, nanofibrous structures exhibit interesting features, such as high surface area, surface functionalization and porosity. In this study, silicate-based 45S5 and 13-93 bioactive glass fibers were fabricated using electrospinning technique and their in vitro mineralization behavior was investigated in two different artificial saliva solutions for various time intervals. Results revealed that both 45S5 and 13-93 bioactive glass fibers show high mineralization behavior in artificial saliva solutions. However different hydroxyapatite (HA) formation rates were observed depending on the glass type and the artificial saliva composition. HA formation initiated earlier in 45S5 glass fibers treated in artificial saliva compared to 13-93 glass. On the other hand, after 30 days of treatment, the surface of 13-93 glass fibers converted to pure crystalline HA, whereas, 45S5 glass surface contained some additional crystalline phases such as aragonite and calcite. Treatment in SAGF medium resulted with better HA conversion ability compared to Carter-Brugirard saliva for both types of glass fibers. In conclusion, the use of electrospun nanofibrous 45S5 and 13-93 bioactive glass scaffolds could be one approach suitable to dental applications. © 2016 Elsevier Ltd and Techna Group S.r.l.
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    Preparation and mineralization of 13-93 bioactive glass-containing electrospun poly-epsilon-caprolactone composite nanofibrous mats
    (SAGE Publications Ltd, 2019) Konyalı R.; Deliormanlı A.M.
    In this study, silicate- based 13-93 bioactive glass (BG) /poly-ε-caprolactone (PCL) nanocomposite fiber mats were fabricated through electrospinning. To prepare composites, amorphous electrospun bioactive glass nanofibers (BGFs) or melt-derived microscale bioactive glass particles (BGPs) were incorporated into the PCL matrix. In vitro mineralization ability of the prepared fibrous mats was assessed in simulated body fluid under static conditions. The results revealed that it is possible to prepare bead-free continuous nanofibers using PCL-acetone solution at specified PCL concentrations (8 and 10 wt%). Nanofibers with almost uniform diameters were produced using 10 wt% PCL solution. Incorporation of BG in the form of particle or fiber into the PCL matrix was made between 1 wt% and 10 wt%. The results showed that the diameter of BGP-containing composite fibers was higher compared to BGF-containing composite scaffolds. The addition of BG to the PCL matrix both in the form of powder and fiber enhanced hydroxyapatite formation in the fibrous scaffolds. The amount of calcium phosphate–based material formation was higher in glass particle–containing samples compared to glass fiber–containing PCL scaffolds. Additionally, the degradation rate in phosphate buffer and silicium ion release amount of BGP-containing PCL fibers was higher compared to BGF-containing PCL fibers. It was concluded that fibrous composite scaffolds prepared in this study could have potential in tissue engineering applications. © The Author(s) 2018.
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    Bioactive glass/hydroxyapatite- containing electrospun poly (ε-Caprolactone) composite nanofibers for bone tissue engineering
    (Springer International Publishing, 2019) Deliormanlı A.M.; Konyalı R.
    In this study, bioactive glass and hydroxyapatite (HA)-containing poly(ε-caprolactone) (PCL) nanocomposite fiber mats were fabricated through electrospinning. For this purpose, microscale bioactive glass (silicate-based 45S5 and borate-based 13-93B3 compositions) or HA particles (at 10 wt%) were incorporated into the PCL matrix. The fabricated biocomposite fibers were investigated in terms of morphological and chemical properties. An in vitro mineralization assay in simulated body fluid was performed to understand the capability of the composite electrospun fibers to induce the formation of hydroxycarbonate apatite. Results showed that the diameter of the electrospun PCL-based fibrous scaffolds increased by the inclusion of bioactive glass or HA particles. All of the fibrous mats prepared in the study showed hydrophobic character. Relatively high contact angles (> 90°) obtained for fibrous scaffolds was attributed to the high porosity and surface roughness. Bioactive glass or HA addition to the PCL matrix enhanced the bioactivity of the fibrous scaffolds. The deposition rate of calcium phosphate-based material precipitates was higher on the surface of HA-containing samples compared to bioactive glass-containing PCL scaffolds. Additionally, mineralization ability of borate-based 13-93B3 glass-containing samples was higher compared to 45S5 glass-containing PCL fibers. The biocomposite fibrous scaffolds prepared in the study may find applications in wound healing as wound dressing and in bone tissue engineering. © 2018, Australian Ceramic Society.