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Total 45 records

    Design and Laboratory Evaluation of Slurry Seal Mixes

    , M.Sc. Thesis Sharif University of Technology Saghafi, Mahdi (Author) ; Tabatabaee, Nader (Supervisor)
    Abstract
    Pavement preventive maintenance methods such as slurry seals are cost-effective treatments that enhance pavement longevity. Incorporation of recycled materials such as reclaimed asphalt pavement (RAP) into asphalt pavements helps further reduce costs and energy consumption. Because the use of emulsions and pavement preventive methods is uncommon in Iran, there is little experience with the technology in this area. The present study designed and developed slurry seal and emulsion test devices at Sharif University lab to study the feasibility of incorporation of RAP into slurry seal mixtures while respecting the limits specified by the ISSA and ASTM. Two slurry seal mixtures in which cement... 

    Characterization of RAP Binder and Warm Mix Asphalt Containing High RAP Percentage and Crumb Rubber

    , M.Sc. Thesis Sharif University of Technology Morsali, Atefeh (Author) ; Tabatabaei, Nader (Supervisor)
    Abstract
    Increased environmental concerns and high oil prices have encouraged highway agencies to maximize the use of recycled materials like Reclaimed Asphalt Pavements (RAP) in pavement construction. However, utilization of RAP has limited to low percentage, generally less than 25%. This is due aged, stiffer, and less strain tolerant asphalt binder in RAP. As the RAP proportion increases, a large amount of the aged binder will be introduced into the mixture. The excessive stiffness of HMA mixture tends to lead to less workable mixture. Studies were conducted to examine the effect of Sasobit on the workablility of high RAP mixtures. The results indicated while the utilization of Sasobit had improved... 

    Effect of Hydrated Lime on Performance Properties of Hot Mix Asphalt

    , M.Sc. Thesis Sharif University of Technology Nabizadeh Shahri, Hadi (Author) ; Tabatabaee, Nader (Supervisor)
    Abstract
    Hydrated lime has been used as an anti-stripping agent with acceptable performance. Numorous studies have been conducted to evaluate hydrated lime as an anti-stripping agent, however effect of hydrated lime on performance properties of asphalt mixture has not been fully addressed. In the present study, the effect of hydrated lime was investigated. In this study, three methods of adding hydrated lime were evaluated. These methods consist of a) adding dry hydrated lime to dry aggregates, b) adding hydrated lime to the binder to form mastic, and c) adding slurry lime to dry aggregates.
    More uniform distribution of hydrated lime on aggregate surface in the slurry method improved performance... 

    AlV Alloy by Aluminothermic Reduction of Vanadium Pentoxide

    , M.Sc. Thesis Sharif University of Technology Saboor Bagherzadeh, Elahe (Author) ; Halali, Mohammad (Supervisor)
    Abstract
    In the present work, aluminothermic reduction of vanadium pentoxide have been used to produce aluminium vanadium alloys. The effect of addition of lime and excess aluminium on the produced alloy was studied. The experiments were carried out in air and in argon. The alloys microstructure were analyzed bu light and scanning electron microscopy. Other methods such as XRD, XRF, ICP, AAS and titration were employed to analyzed the alloy and the slag. It was found that the addition of lime and excess aluminium increase the yield of the alloy. Vanadium recovery was not affected by the atmosphere used.
     

    The effects of a hydrochloric acid pre-treatment on the physicochemical properties and pozzolanic performance of rice husk ash

    , Article Cement and Concrete Composites ; Volume 39 , 2013 , Pages 131-140 ; 09589465 (ISSN) Gholizadeh Vayghan, A ; Khaloo, A. R ; Rajabipour, F ; Sharif University of Technology
    2013
    Abstract
    This paper investigates the effects of acid normality (0.01-6 N HCl) and combustion retention time (0.25- 16 hours) on the pozzolanic properties of pre-combustion acid-treated rice husk ash. The pozzolanic reactivity was quantified by adding ground ash to saturated Ca(OH)2 solutions and monitoring the time-dependent electrical conductivity and pH of the solutions. Also, the strength activity of ashes from different processes was measured by testing the compressive strength of mortars. It was observed that acid treatment results in ashes with higher SiO2 content, lower alkali and unburned carbon content, better grindability, and smaller particle size, in comparison with ash from non-acid... 

    In vitro study of hydroxyapatite/polycaprolactone (HA/PCL) nanocomposite synthesized by an in situ sol-gel process

    , Article Materials Science and Engineering C ; Volume 33, Issue 1 , 2013 , Pages 390-396 ; 09284931 (ISSN) Rezaei, A ; Mohammadi, M. R ; Sharif University of Technology
    2013
    Abstract
    Hydroxyapatite (HA) is the most substantial mineral constituent of a bone which has been extensively used in medicine as implantable materials, owing to its good biocompatibility, bioactivity high osteoconductive, and/or osteoinductive properties. Nevertheless, its mechanical property is not utmost appropriate for a bone substitution. Therefore, a composite consist of HA and a biodegradable polymer is usually prepared to generate an apt bone scaffold. In the present work polycaprolactone (PCL), a newly remarkable biocompatible and biodegradable polymer, was employed as a matrix and hydroxyapatite nanoparticles were used as a reinforcement element of the composite. HA/PCL nanocomposites were... 

    Synthesis of W17O47 nanothick plates with preferred orientation and their photocatalytic activity

    , Article Surface and Interface Analysis ; Volume 43, Issue 11 , 2011 , Pages 1397-1402 ; 01422421 (ISSN) Azimirad, R ; Khosravi, P ; Moshfegh, A. Z ; Sharif University of Technology
    Abstract
    A simple method for synthesis of W17O47 nanothick plates by annealing sol-gel-deposited tungsten oxide thin films on soda lime substrate has been reported. After heat treatment of the dried thin films at 700 °C in N2 ambient for 60 min, W17O47 nanothick plates with [100] orientation were obtained. The synthesized product was characterized and analyzed by, X-ray diffraction (XRD), SEM, XPS and ultraviolet-visible spectrophotometery. According to SEM observations, nanothick plates grew with random orientations on the surface. In addition, it was observed that some of the nanothick plates were constituted from several nanosheets. XRD analysis determined that the nanothick plates were mainly... 

    Biodiesel production using CaO/γ-Al2O3 catalyst synthesized by sol-gel method

    , Article Canadian Journal of Chemical Engineering ; Volume 93, Issue 9 , July , 2015 , Pages 1531-1538 ; 00084034 (ISSN) Moradi, G ; Mohadesi, M ; Rezaei, R ; Moradi, R ; Sharif University of Technology
    Wiley-Liss Inc  2015
    Abstract
    In this study, 40% CaO/γ-Al2O3 catalyst was used for biodiesel production from corn oil. A transesterification reaction was done for 5h at a temperature of 65°C in the presence of corn oil, methanol (methanol to oil molar ratio of 12:1), and CaO/γ-Al2O3 catalyst (0.06g/g (6wt%)). Catalyst used in this study was synthesized using the sol-gel method. In this method, two parameters of gelation temperature and nitric acid concentration were used as variables in the catalyst synthesis step, and experiments were designed using central composite design (CCD). The results indicate that the optimal point is achieved at a gelation temperature of 70°C and... 

    Nanomechanical properties of TiO2 granular thin films

    , Article ACS Applied Materials and Interfaces ; Volume 2, Issue 9 , 2010 , Pages 2629-2636 ; 19448244 (ISSN) Yaghoubi, H ; Taghavinia, N ; Keshavarz Alamdari, E ; Volinsky, A.A ; Sharif University of Technology
    2010
    Abstract
    Post-deposition annealing effects on nanomechanical properties of granular TiO2 films on soda-lime glass substrates were studied. In particular, the effects of Na diffusion on the films' mechanical properties were examined. TiO2 photocatalyst films, 330 nm thick, were prepared by dip-coating using a TiO2 sol, and were annealed between 100 °C and 500 °C. Film's morphology, physical and nanomechanical properties were characterized by atomic force microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, differential thermo-gravimetric analysis, and nanoindentation. Contrary to expectations, the maximum film hardness was achieved for 300°C annealing, with a value of 0.69 ± 0.05 GPa.... 

    Characterization of optical properties of amorphous BaTiO3 nanothin films

    , Article Journal of Non-Crystalline Solids ; Volume 355, Issue 50-51 , 2009 , Pages 2480-2484 ; 00223093 (ISSN) Ashiri, R ; Nemati, A ; Sasani Ghamsari, M ; Aadelkhani, H ; Sharif University of Technology
    Abstract
    Amorphous barium titanate nanothin films were prepared by sol-gel dip-coating method. According to transmission spectrum, the refractive index and optical band gap of nanothin films have been determined. High transmission spectrum without any fluctuation in visible wavelength region was recorded. Experimental results indicated that the surface morphology of prepared nanothin films were improved and as a result of that, a better optical properties, less optical losses and higher band gap width were obtained in contrast with other reported data. It was found that optical propagation loss of BaTiO3 nanothin film was much lower than normal polycrystalline BaTiO3 thin film. It seems to us that,... 

    Effects of moisture on warm mix asphalt containing Sasobit

    , Article Scientia Iranica ; Volume 24, Issue 4 , 2017 , Pages 1866-1873 ; 10263098 (ISSN) Nabizadeh, H ; Naderi, B ; Tabatabaee, N ; Sharif University of Technology
    Sharif University of Technology  2017
    Abstract
    The asphalt industry has been at the forefront of sustainable development. Warm Mix Asphalt (WMA) has been developed to cope with issues such as high energy prices and air pollution. These mixes require less energy and generate fewer pollutants during production in comparison with conventional Hot Mix Asphalt (HMA). Although a promising technology, the durability of WMA is not clear because long-term WMA field performance data is limited. This study investigated the susceptibility of Sasobit-modified WMA to moisture, since moisture damage is a major cause of premature pavement failure in asphalt concrete. To this end, WMA samples were made using different concentrations of Sasobit and the... 

    Thermodynamic evaluation of adsorption of zinc complex and ZnO nano-layer prepared by tscd method based on langmuir adsorption model

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 22, Issue 2 , 2009 , Pages 179-184 ; 1728-144X (ISSN) Vaezi, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
    Materials and Energy Research Center  2009
    Abstract
    Zinc oxide thin films were deposited on soda-lime glass substrates from an aqueous zinc- containing complex by two-stage chemical deposition (TSCD) method. Longmuir adsorption model showed that the adsorption of atoms on the surface of the substrate was typically physical. The relation between the fractional coverage, θ, with the equilibrium constant of the adsorption reaction was nonlinear indicating that the adsorption was non-ideal. The percentage of porosity, 1-θ, of the thin layer was determined as a function of Zn 2+ concentration of the solution. By application of XRD technique, it was shown that pure crystalline ZnO of controllable thickness could be deposited by TSCD method on the... 

    Integrated image processing and computational techniques to characterize formation damage

    , Article SPE International Conference and Exhibition on Formation Damage Control 2018, 7 February 2018 through 9 February 2018 ; Volume 2018-February , 2018 Ezeakacha, C. P ; Rabbani, A ; Salehi, S ; Ghalambor, A ; Sharif University of Technology
    Society of Petroleum Engineers (SPE)  2018
    Abstract
    Filtrate and solid invasion from drilling fluids are two key sources of formation damage, and can result in formation permeability impairment. Typically, spurt invasion of mud solids causes the evolution of an external mud cake which tends to reduce further solids and filtrate influx. However, uncontrolled spurt and filtrate invasion are detrimental because they reduce the permeability of the formation. Mud composition, formation rock's permeability and porosity, and temperature can influence both spurt and filtrate invasion. The sizes of mud solids relative to the average pore size of a rock are also important in predicting the extent of mud invasion and permeability impairment. In this... 

    Mechanism of nanostructured fluorapatite formation from CaO, CaF2 and P2O5 precursors by mechanochemical synthesis

    , Article Progress in Reaction Kinetics and Mechanism ; Volume 43, Issue 3-4 , 2018 , Pages 201-210 ; 14686783 (ISSN) Nikonam Mofrad,, R ; Sadrnezhaad, S. K ; Vahdati Khaki, J ; Sharif University of Technology
    Science Reviews 2000 Ltd  2018
    Abstract
    We determined the mechanism of mechanochemical synthesis of fluorapatite from CaO, CaF2 and P2O5 by characterisation of the intermediate compounds. We used atomic absorption spectroscopy, X-ray diffraction, field emission scanning electron microscopy, FTIR spectroscopy and transmission electron microscopy to find the transitional compounds. Investigation of the binary and ternary powder mixtures revealed the appearance of H3PO4, Ca(OH)2, Ca2P2O7 and CaCO3 as the intermediate compounds. At early stages of the milling, conversions of P2O5 to H3PO4 and CaO to Ca(OH)2 occurred in the wet atmosphere. Later, a combination of Ca(OH)2 and H3PO4 formed Ca2P2O7 while the unreacted CaO was converted to... 

    Growth of Na0.3WO3 nanorods for the field emission application

    , Article Journal of Physics D: Applied Physics ; Volume 42, Issue 20 , 2009 ; 00223727 (ISSN) Azimirad, R ; Khademi, A ; Akhavan, O ; Zaker Moshfegh, A. R ; Sharif University of Technology
    2009
    Abstract
    Na0.3WO3 1D nanostructure forms (nanorods and nanobelts) were grown by a solid-liquid-solid mechanism from a 40 nm sputtered tungsten film deposited on a soda-lime substrate and annealed at 700 °C in a tubular furnace in N2 ambient. The morphology, structure, composition and chemical state of the prepared nanostructures were characterized by SEM, XRD, TEM, SAED and XPS measurements. The Na0.3WO3 1D nanostructures were found to have a cubic crystalline structure and grown along the [0 0 1] direction. The nanorods are a few micrometres in length and about 50 nm in diameter. The field-emission application of the prepared samples at different distances between the cathode and the anode was... 

    Simple method to synthesize NaxWO3 nanorods and nanobelts

    , Article Journal of Physical Chemistry C ; Volume 113, Issue 30 , 2009 , Pages 13098-13102 ; 19327447 (ISSN) Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    2009
    Abstract
    A simple method for synthesis of NaxWO3 nanorods and nanobelts on sputtered tungsten films by using sodium in soda lime substrate as the catalyst was reported for the first time. After thermally post annealing thin films in a temperature range of 600-750 °C in N2 ambient for 80 min, crystalline NaxWO3 nanorods and nanobelts with [001] direction were formed depending on the annealing temperature. Experimental results reveal that the annealing temperature at 700 °C is the optimum temperature for the growth of sodium-doped tungsten oxide nanorods with maximum density on the surface. According to scanning electron microscopic observations, the synthesized nanorods are ∼50 nm in width and a few... 

    Study on mechanical properties of ternary blended concrete containing two different sizes of nano-SiO2

    , Article Composites Part B: Engineering ; Volume 167 , 2019 , Pages 20-24 ; 13598368 (ISSN) Nazerigivi, A ; Najigivi, A ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    The aim of this study was to investigate the influences of combination of the two different SiO2 nanoparticles (15 nm and 80 nm) on compressive, flexural and tensile strength of ternary blended concrete. SiO2 nanoparticles with two different sizes of 15 and 80 nm have been used as a partial cement replacement by 0.5, 1.0, 1.5 and 2.0 wt.% in 16 different proportions of mixture followed by curing in lime solution for 7, 28 and 90 days. The results indicate that in all curing ages in lime solution specimens with 2.0% of 15 nm plus 1.5% of 80 nm cement replacement achieved higher mechanical properties. The continuous cement paste with the lowest delicate zones might be due to the fact of quick... 

    The effect of filler type and content on rutting resistance of asphaltic materials

    , Article International Journal of Pavement Research and Technology ; Volume 12, Issue 3 , 2019 , Pages 249-258 ; 19966814 (ISSN) Hamidi, A ; Motamed, A ; Sharif University of Technology
    Springer  2019
    Abstract
    This research evaluates the effect of filler type and content on rutting resistance of asphaltic materials by using laboratory experiments. To examine the effect of filler type, two traditional fillers (Silica sandstone powder and Portland cement) and a new recycled lime powder (Eggshell) were considered. To investigate the effect of filler content, three different filler contents were used. Marshall Stability test was performed on full mixes in order to determine the optimum binder content of the mixtures. Then, the static creep test was performed on Fine Aggregate Matrix (FAM) samples. The permanent strain after 10 minutes of recovery (PS-660) was considered as the indicator of potential... 

    Effects of saturation degrees, freezing-thawing, and curing on geotechnical properties of lime and lime-cement concretes

    , Article Cold Regions Science and Technology ; Volume 160 , 2019 , Pages 242-251 ; 0165232X (ISSN) Jahandari, S ; Saberian, M ; Tao, Z ; Mojtahedi, S.F ; Li, J ; Ghasemi, M ; Rezvani, S. S ; Li, W ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    There are very limited researches carried out to investigate the influence of saturation degrees, freezing-thawing, and curing times on geotechnical properties of lime concrete (LC) and lime-cement concrete (LCC) due to the capillary action and changes in groundwater table. Subsequently, the primary goal of this research is to investigate the influence of these parameters on mechanical properties of LC and LCC using unconfined compression tests, namely uniaxial compressive strength (UCS), stress-strain behavior, deformability index (I D ), secant modulus (E S ), failure strain, bulk modulus (K), resilient modulus (M R ), brittleness index (I B ), and shear modulus (G). At first, the... 

    The effects of stabilizers on the thermal and the mechanical properties of rammed earth at various humidities and their environmental impacts

    , Article Construction and Building Materials ; Volume 200 , 2019 , Pages 616-629 ; 09500618 (ISSN) Toufigh, V ; Kianfar, E ; Sharif University of Technology
    Elsevier Ltd  2019
    Abstract
    The overall behavior of rammed earth (RE) as a low embodied energy construction method can be enhanced by using stabilizers. Several studies have been performed on cement and lime stabilized RE. However, studies on other additives, especially the sustainable ones, are limited. In this research, the effect of stabilizers including cement, pozzolan, microsilica, fiberglass, guar gum and phase change material (PCM) was evaluated on the performance of RE mixtures. The mixtures were assessed by considering the durability, shrinkage, thermal conductivity, mechanical properties and their sensitivity to the humidity. Then, the correlations were determined between the mechanical properties and the...