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    Effect of Zirconia Content and Powder Processing on Mechanical Properties of Gelcasted ZTA Composite

    , Article Transactions of the Indian Ceramic Society ; Volume 72, Issue 3 , May , 2013 , Pages 175-181 ; 0371750X (ISSN) Khoshkalam, M ; Faghihi Sani, M. A ; Nojoomi, A ; Sharif University of Technology
    Addition of fine zirconia particles in the alumina matrix in order to produce ZTA composite is a well-known method for improving the mechanical properties of alumina ceramics such as flexural strength and fracture toughness. Increasing homogeneity and reducing alumina grain size are two key factors for achieving proper mechanical properties in this ceramic matrix composite. In this work two batches of ZTA powder precursor were prepared through mixing of alumina and zirconia by ball milling and in situ synthesis of ZTA composite via solution combustion method. The bending strength testing samples were fabricated through gel-casting process. The effects of different powder processing methods... 

    Improving the performance of cement-based composites containing superabsorbent polymers by utilization of nano-SiO2 particles

    , Article Materials and Design ; Volume 42 , 2012 , Pages 94-101 ; 02641275 (ISSN) Pourjavadi, A ; Fakoorpoor, S. M ; Khaloo, A ; Hosseini, P ; Sharif University of Technology
    The application of superabsorbent polymer (SAP) as an internal curing agent for cement based composites results in benefits such as reduced autogenous shrinkage and cracking. However, a reduction in compressive and flexural strength usually occurs due to the empty voids remained in the matrix after deswelling of SAP particles. Nanoparticles are good candidates for improving the mechanical performance of cementitious materials, due to their multiple mechanisms of action, not the least their high pozzolanic activity.In the present work, the capability of amorphous nano-SiO2 (NS) as the most widely used nanoparticle in cementitious materials, for retrieving mechanical properties of... 

    Production of waste bio-fiber cement-based composites reinforced with nano-SiO 2 particles as a substitute for asbestos cement composites

    , Article Construction and Building Materials ; Volume 31 , 2012 , Pages 105-111 ; 09500618 (ISSN) Hosseinpourpia, R ; Varshoee, A ; Soltani, M ; Hosseini, P ; Ziaei Tabari, H ; Sharif University of Technology
    The environmental impact of asbestos fibers on human health and their consequent safety-related problems indicate that there is a significant need to replace this material in all asbestos-containing products. Many different types of fibers have been introduced to replace asbestos fibers. In this study, the performance of silica nano-particles combined with waste paper pulp fibers (sulfite fibers) has been investigated. Different mechanical (compressive and flexural strengths and bending performance), durability (water absorption), physical (bulk density and flowability), and microstructural (scanning electron microscopy) tests were conducted to examine the properties of manufactured green... 

    Effects of pozzolans together with steel and polypropylene fibers on mechanical properties of RCC pavements

    , Article Construction and Building Materials ; Volume 26, Issue 1 , January , 2012 , Pages 102-112 ; 09500618 (ISSN) Madhkhan, M ; Azizkhani, R ; Torki Harchegani, M. E ; Sharif University of Technology
    Effects of pozzolans and fibers on mechanical properties of RCC are addressed. The mechanical properties were evaluated using optimum moisture with different amounts of pozzolans, steel and polypropylene fibers. Using pozzolans, maximum increase in compressive strength was observed to occur between 28 and 90 days of age, rupture modulus was found to decrease; but toughness indices did not change considerably. The influence of steel fibers on compressive strength was often more significant than that of PP fibers; but neither steel nor PP fibers did contribute to increase in the rupture modulus independently from pozzolans. Also, the toughness indices increased when steel fibers were used  

    Roller compacted concrete pavements reinforced with steel and polypropylene fibers

    , Article Structural Engineering and Mechanics ; Volume 40, Issue 2 , 2011 , Pages 149-165 ; 12254568 (ISSN) Madhkhan, M ; Azizkhani, R ; Torki, M. E ; Sharif University of Technology
    In this paper, the effects of both pozzolans and (steel and poly-propylene) fibers on the mechanical properties of roller compacted concrete are studied. Specimens for the experiments were made using a soil-based approach; thus, the Kango's vibration hammer was used for compaction. The tests in the first stage were carried out to determine the optimal moisture requirements for mix designs using cubic 150 × 150 × 150 mm specimens. In the tests of the second stage, the mechanical behaviors of the main specimens made using the optimal moisture obtained in the previous stage were evaluated using 28, 90, and 210 day cubic specimens. The mechanical properties of RCC pavements were evaluated using... 

    Experimental study of RC jacketed and CFRP strengthened RC beams

    , Article Construction and Building Materials ; Volume 95 , October , 2015 , Pages 476-485 ; 09500618 (ISSN) Tahsiri, H ; Sedehi, O ; Khaloo, A ; Raisi, E. M ; Sharif University of Technology
    Elsevier Ltd  2015
    This paper presents the results of an experimental study on retrofitting RC beams using FRP strengthening and RC jacketing. Three-point loadings are applied to twelve strengthened beams and three reference specimens to put the two techniques into perspective. Formation of first cracks, FRP debonding, and onset of concrete crushing are compared and discussed. Load-deflection behavior, failure modes, and crack propagation patterns are studied extensively. The experiments demonstrate that the RC jacketed beams exhibit a flexural failure identical to the reference beams. However, the FRP strengthened beams fail in a relatively small deflection due to the premature FRP debonding. Furthermore, the... 

    Effects of nucleation agent particle size on properties, crystallisation and microstructure of glass-ceramics in TiO2-ZrO2-Li 2O-CaO- Al2O3-SiO2 system

    , Article Advances in Applied Ceramics ; Volume 109, Issue 6 , 2010 , Pages 318-323 ; 17436753 (ISSN) Nemati, A ; Goharian, P ; Shabanian, M ; Afshar, A ; Sharif University of Technology
    The objective of this study was to evaluate the effects of P 2O5 particle size distribution on the crystalline phases and microstructure of lithium disilicate glass-ceramics derived from the TiO2-ZrO2-Li2O-CaO-Al2O 3-SiO2 system for dentistry applications. The samples were made via fusion and casting procedure. Crystallisation as well as the morphology and microstructure of the samples were investigated using X-ray diffraction, differential scanning calorimetric and scanning electron microscopy. The results showed that the crystallisation of the samples occurred in the range of 500-650°C. The main crystalline phase was lithium disilicate (Li2Si2O5) along with Lithium metasilicate (Li2SiO3),... 

    Influence of nano-SiO2 addition on microstructure and mechanical properties of cement mortars for ferrocement

    , Article Transportation Research Record ; Issue 2141 , 2010 , Pages 15-20 ; 03611981 (ISSN) Hosseini, P ; Booshehrian, A ; Farshchi, S ; Sharif University of Technology
    Because of their unique physical and chemical properties, nanoparticles have been gaining increasing attention and have been used in many fields to fabricate new materials with novel functions. If nanoparticles are integrated with cement-based building materials, the new materials might possess some outstanding properties. Ferrocement is a type of thin-wall reinforced concrete commonly constructed of hydraulic cement mortar reinforced with closely spaced layers of continuous and relatively small-sized wire mesh. The low level of technical skill required to make ferrocement and the ready availability of its materials make ferrocement suitable for a wide variety of applications. This study... 

    Densification and properties of Fe2O3 nanoparticles added CaO refractories

    , Article Ceramics International ; 2016 ; 02728842 (ISSN) Ghasemi Kahrizsangi, S ; Nemati, A ; Shahraki, A ; Farooghi, M ; Sharif University of Technology
    Elsevier Ltd 
    Up to 8wt. % of Nano-iron oxide was added to CaO refractory matrix. The crystalline phases and microstructure characteristics of specimens sintered at 1650°C for 5h in an electric furnace were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The physical properties are reported in terms of bulk density, apparent porosity and hydration resistance. The mechanical behavior was studied by a cold crushing strength (CCS) and flexural strength at 1200°C test. As a result, it was found that the presence of Nano-iron oxide in the CaO refractory matrix induced 2CaO.Fe2O3 (C2F), CaO.Fe2O3 (CF) and 3CaO.Al2O3 (C3A) phase's formation, which improved the sintering... 

    Evaluation of Seismic Behavior of Coupling Beam in Shear Walls

    , M.Sc. Thesis Sharif University of Technology Arianfar, Roshan (Author) ; Moghaddam, Hassan (Supervisor)
    In evaluating the damage observed in the structures can be seen that the beam to the wall connection in the walls with openings has severe damage and repair and reconstruction of the beams at the connection is very expensive and difficult. One way to improve seismic behavior and reduce damage in the beams are using steel fibers. Hence in the present study the effect of different fibers in seismic behavior of coupling beams with different length to depth ratio are investigated. The concrete used in the beams of high strength concrete (C60). Therefore, nine model with length to depth ratio of 1.75, 2.25 and 2.75 first without fiber and then with 1.5 and 3 percent made in ABAQUS software. This... 

    Behavior of polymer concrete beam/pile confined with CFRP sleeves

    , Article Mechanics of Advanced Materials and Structures ; 2017 , Pages 1-8 ; 15376494 (ISSN) Toufigh, V ; Toufigh, V ; Saadatmanesh, H ; Ahmari, S ; Kabiri, E ; Sharif University of Technology
    This research investigates the flexural behavior of a polymer concrete beam/pile encased with carbon fiber sleeve. The mechanical properties of carbon fiber sleeves in tension and cement and polymer concrete in compression were determined. Polymer concrete beams were tested in flexure to determine the bending moment capacity. Then, the test results were compared to the theoretical model results. Finally, a parametric study was conducted to determine the influence of beam/pile parameters on the capacity of the element. Based on the investigation, carbon fiber sleeve filled with polymer concrete exhibits outstanding structural performance including ductility and bending capacity. © 2017 Taylor... 

    Synthesis and characterization of diopside glass-ceramic matrix composite reinforced with aluminum titanate

    , Article Ceramics International ; Volume 35, Issue 4 , 2009 , Pages 1447-1452 ; 02728842 (ISSN) Yousefi, M ; Alizadeh, P ; Eftekhari Yekta, B ; Molaie, F ; Ghafoorian, N ; Montazerian, M ; Sharif University of Technology
    Glass-ceramic composites in the SiO2-CaO-MgO-(Na2O) system, reinforced with 5, 10 and 20 wt.% aluminum titanate were synthesized by pressureless sintering. Optimum sintering temperatures with maximum relative density were determined for each composition. The composites were fired above the crystallization peak temperature of glass-ceramic. Mechanical properties of glass-ceramic and sintered composites, such as fracture toughness, flexural strength and Vickers microhardness, were investigated. The sintered composites were characterized by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that the composite containing 10... 

    Experimental Studies on Mechanical Properties of Cement Mortar Including Nano Alumina and Nano Silica

    , M.Sc. Thesis Sharif University of Technology Jafari Rahmatabadi, Mohammad Hossein (Author) ; Joghataie, Abdollreza (Supervisor)
    Due to the diameter and size of nanoparticles, they have been applied in various fields to make materials with better properties. In this thesis, the purpose has been to investigate the influence of nano alumina and nano alumina incorporating nano silica particles on mechanical properties of cement mortars. Different portions of nano alumina that include 1, 3, and 5% have been used. Nano silica with 1 and 2% has been used. At first, nano particles were dispersed by sonication with water, and then the cement mortars with various percent of nano additives with the same workability have been made. After different curing periods (7, 28 days), the specimens have been tested for bending and... 

    Investigation of the fracture resistance in hoop wound composites modified with two different reactive oligomers

    , Article Materials and Design ; Volume 30, Issue 8 , 2009 , Pages 3048-3055 ; 02641275 (ISSN) Abadyan, M ; Bagheri, R ; Haddadpour, H ; Motamedi, P ; Sharif University of Technology
    Rubber modification of hoop filament wound epoxy composites was investigated using amine-terminated butadiene acrylonitrile (ATBN) and carboxyl-terminated butadiene acrylonitrile (CTBN) oligomers. Both mechanical and physical properties of modified composites were investigated and the morphology of the samples was studied via scanning electron microscopy. Results indicated that, when added to the epoxy matrix, ATBN effected a superior increase in toughness, yet a more severe decline in compressive and flexural strength, compared to CTBN. In contrast, in the case of composite samples, incorporation of ATBN led to more favorable mechanical properties, from the viewpoint of both toughness and... 

    Use of rubber modification technique to improve fracture-resistance of hoop wound composites

    , Article Materials and Design ; Volume 30, Issue 6 , 2009 , Pages 1976-1984 ; 02641275 (ISSN) Abadyan, M ; Khademi, V ; Bagheri, R ; Haddadpour, H ; Kouchakzadeh, M. A ; Farsadi, M ; Sharif University of Technology
    Toughness improvement of an epoxy resin and respective hoop wound composite were investigated systematically using amine-terminated butadiene acrylonitrile (ATBN) liquid rubber. Rubber modification improves fracture toughness of epoxy resin with slight reduction in the glass transition temperature (Tg), flexural and compressive properties of resin. Impact resistance of composite is improved by rubber modification similar to modified resin. Interlaminar shear strength (ILSS), compressive modulus and strength, and flexural strength of composite decreased slightly with rubber modification. To interpret the data, the void content of composite samples was determined and the damaged surfaces of... 

    Flexural Strengthening of Reinforced Concrete Beams by FRP Composites to Reduce Creep Deflection

    , M.Sc. Thesis Sharif University of Technology Zarringol, Mohammad Reza (Author) ; Kazemi, Mohammad Taqhi (Supervisor)
    The strengthening of reinforced concrete structures with externally bonded fibre reinforced polymer (FRP) laminates has shown excellent performance, so this technology is rapidly replacing externally bonded steel plates, steel or concrete jackets, and many traditional techniques available. In this study strengthening of reinforced concrete beams by GFRP to reduce creep deflection is investigated by mathematical method using available relations. Five RC beams with different dimensions, with and without strengthening with GFRP laminate, were investigated for their creep deflection. The creep coefficient of beams selected from experimental result that were mentioned in RILEM DATA BANK. In this... 

    Finite Element Modeling of Flexural Behavior of RC Beams Using FRP

    , M.Sc. Thesis Sharif University of Technology Jafarzadeh Eslami, Mehran (Author) ; Rahimzadeh Rofooei, Fayyaz (Supervisor)
    The flexural behavior of reinforced concrete beams through application of FRP is studied, considering FRP-concrete bonding. Moreover, the nonlinear behavior of concrete (generation of crack and crush) is taken into consideration. Different parameters such as the number of layers of CFRP sheets, the effect of tensile reinforcing bars, the effect of using glass fibers, and modeling resin layer between the concrete and FRP are investigated. The results are compared with the existing experimental tests and those obtained from analytical method, ACI 440.2R-08 and ISIS Canada. The results show that by adding CFRP sheet to the control beam, the stiffness and flexural strength of the beam improves... 

    Flexural Behavior of Concrete Beams Strengthened by Classical Method and Comparing The Results with Strengthening by FRP

    , M.Sc. Thesis Sharif University of Technology Moradkhani Pour, Behnam (Author) ; Khaloo, Alireza (Supervisor)
    Retrofitting and strengthening existing structures is one of the most important concepts of structural and earthquake engineering. Strengthening of structures could be due to changes in application and applied load, errors in calculation, mistakes in construction, weakness of old codes, structural height increases and changes in environmental conditions. Different methods for increasing the flexural strength and ductility of reinforced concrete beams, as one of the major structural components, have been presented. This research presents an experimental study on the strengthening of reinforced concrete beams by reinforced concrete jackets (classical method) and Fiber Reinforced Polymer (FRP)... 

    Flexural Failure Mechanism of Concrete Beams Strengthened with FRP and Comparing The Result With Classic Method Of Strengthening

    , M.Sc. Thesis Sharif University of Technology Tahsiri, Hamid Reza (Author) ; Khaloo, Alireza (Supervisor)
    Retrofitting of reinforced concrete and steel structures is a very important issue in Structural Engineering due to the reasons such as drawbacks in previous codes, revision of application of structures , destructive environmental factors and deficiencies in construction process.
    Strengthening of structures with FRP composites is one of the methods that have been welcomed by researchers due to its unique properties including high tensile strength, light weight, simple application and resistance to corrosive environment. Although the main purpose of retrofitting is to increase the overall load carrying capacity of the structures, the failure mechanism of the strengthened member is also... 

    Influence of Notch Location on Fiber Reinforced High-Strength Concrete Beams

    , M.Sc. Thesis Sharif University of Technology Rezaei Saleh, Benyamin (Author) ; Khaloo, Alireza (Supervisor)
    The daily development of societies and the advancement of various industries have led civil engineering to save on and use of environmentally friendly materials. Urban development and population concentration In some areas, Encourages engineers To use materials with more efficiency to design High-rise structures that have more lifetime or maintain them using modern methods. Concrete in most structures has a significant percentage of consumable materials, but it has limited tensile strength and flexibility. Fiber can be used to control the growth of cracks, prolonging useful life, controlling permeability and corrosion. Different types of fibers are used in concrete.In this study, we have...