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Corrigendum: “geopolymers vs. alkali-activated materials (AAMs): a comparative study on durability, microstructure, and resistance to elevated temperatures of lightweight mortars” (JCBM 222 (2019) (49–63), (S0950061819315089), (10.1016/j.conbuildmat.2019.06.079))
, Article Construction and Building Materials ; Volume 283 , 2021 ; 09500618 (ISSN) ; Shoaei, P ; Zareei, A. R ; Behforouz, B ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
The authors regret that there was an error in the XRD pattern for pumice shown in Fig. 8. The authors have re-analyzed the pumice to address the concerns over the reliability of the pattern due to the presence of noises, and the updated XRD pattern has been shown in Fig. 8 here for more accuracy of the presented information. It is noteworthy that this change does not affect any of the conclusions. The authors would like to apologise for any inconvenience caused. © 2021 Elsevier Ltd
Mechanical Properties of Foam Concretes
, M.Sc. Thesis Sharif University of Technology ; Khonsari, Vaheed (Supervisor)
Abstract
Due to the wide application of lightweight concretes, there have been a lot of research activities in this field. The objectives of these activities have been mainly to increase the strength and endurance, and to reduce the weight and the cost of production of such concretes.
Lightweight concretes, in general, have the following advantages: relatively high strength to density ratio, high thermal and acoustic insulation, and fire resistance. However, foam concretes, as a particular type of lightweight concretes, compared with other types, has the advantage of ease of production. Therefore, in this work various aspects of foam concretes were studied. In this project, using a particular...
Lightweight concretes, in general, have the following advantages: relatively high strength to density ratio, high thermal and acoustic insulation, and fire resistance. However, foam concretes, as a particular type of lightweight concretes, compared with other types, has the advantage of ease of production. Therefore, in this work various aspects of foam concretes were studied. In this project, using a particular...
Grafting of acrylamide onto kappa-carrageenan via γ-irradiation: Optimization and swelling behavior
, Article Radiation Physics and Chemistry ; Volume 77, Issue 2 , 2008 , Pages 131-137 ; 0969806X (ISSN) ; Pourjavadi, A ; Sheikh, N ; Sadegh Amini Fazl, M ; Sharif University of Technology
2008
Abstract
The Taguchi method, a robust experimental design for optimization, was used for the synthesis of a superabsorbent hydrogel network using γ-rays as an initiator, energy source and crosslinker at the same time. Nine different samples of superabsorbent hydrogels were prepared in various conditions from kappa-carrageenan (κC) and acrylamide by γ-irradiation at room temperature. Considering the results of nine trials and according to analysis of variance (ANOVA), a new experimental condition with the concentrations of κC and acrylamide 1.5 g and 0.028 mol (2 g in total volume of 50 mL H2O), respectively, as well as γ-ray at the optimum total dose (7 kGy) was proposed. After preparing the desired...
Synthesis, characterization, and swelling behavior of alginate-g- poly(sodium acrylate)/kaolin superabsorbent hydrogel composites
, Article Journal of Applied Polymer Science ; Volume 105, Issue 5 , 2007 , Pages 2631-2639 ; 00218995 (ISSN) ; Ghasemzadeh, H ; Soleyman, R ; Sharif University of Technology
2007
Abstract
A novel superabsorbent composite based on sodium alginate and the inorganic clay kaolin was synthesized via the graft copolymerization of acrylic acid (AA) in an aqueous medium with methylene bisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. The effects of reaction variables, such as the MBA, AA, and APS concentrations and the alginate/kaolin weight ratio, on the water absorbency of the composite were systematically optimized. Evidence of grafting and kaolin interactions was obtained by a comparison of the Fourier transform infrared spectra of the initial substrates with that of the superabsorbent composite, and the hydrogel structure was confirmed...
Performance of sustainable high strength concrete with basic oxygen steel-making (BOS)slag and nano-silica
, Article Journal of Building Engineering ; Volume 25 , 2019 ; 23527102 (ISSN) ; Ameri, F ; Bahrami, N ; Shoaei, P ; Moosaei, H. R ; Salemi, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
This study presents the results of an experimental evaluation of the performance of high strength concrete (HSC)with basic oxygen steel-making (BOS)slag and nano-silica respectively used as a partial replacement of sand and cement. The properties of fresh and hardened concrete specimens containing 25%, 50%, 75%, and 100% BOS as partial replacement of sand and 2% of cement replaced with nano-silica were evaluated. According to the results, concrete samples containing nano-silica with higher BOS percentages, demonstrated improvements in strength and durability properties, while workability was reduced. For example, at 50% BOS content, about 18% increase in compressive strength and 50%...
A Methodology for the Design of an Integration System for Water Capturing, Carbon Capture, and Heat Recovery from Flue Gas in Power Plants
, M.Sc. Thesis Sharif University of Technology ; Avami, Akram (Supervisor)
Abstract
This work presents a mathematical model for retrofitting the steam power plants in a refinery site. This problem is formulated as a mixed-integer nonlinear program (MINLP). Feasible retrofit alternatives suggested by experienced field engineers are investigated in sequence to examine the saving of those possible modifications. Furthermore, techno economic simulation of water and energy recovery systems from boiler flue gasses has been examined to obtain the optimal condition of these systems. For heat recovery, a systematic model for using organic Rankine cycle has been developed and results showed that toluene is the best possible working fluid in this case. Finally, water absorption cycle...
Durability Evaluation and Health Monitoring of Microcracked Slag-Based Geopolymer Concrete Due to Step by Step Pressure Loading
, M.Sc. Thesis Sharif University of Technology ; Ghaemian, Mohsen (Supervisor) ; Toufigh, Vahab (Co-Supervisor)
Abstract
The goal of this research is to study the effect of local microcracking due to step by step pressure loading on the durability properties of geopolymer concrete. To better understand the behavior of GGBS-based GPC under different pressure stress levels, some experiments such as water permeability and water absorption conducted on the samples at each state of damage. Also, non-destructive tests such as ultrasonic waveform and pulse velocity (UPV) was used to quantify the extent of damage at each step. GGBFS and a blend of sodium silicate solution and 10 molar sodium hydroxide solution with SSSH⁄ ratio of 2 were used for production of GPC samples. GPC, OGPC and OPC samples with water to binder...
Extreme light absorption in a necking-free monolayer of resonant-size nanoparticles for photoelectrochemical cells
, Article Journal of Optics (United Kingdom) ; Vol. 16, issue. 7 , 2014 ; ISSN: 20408978 ; Sharif University of Technology
Abstract
Semiconductor photoelectrodes for water oxidation that absorb visible light usually have poor electronic transport properties and small optical absorption coefficients near their absorption edge. Therefore, innovative designs that lead to significant optical absorption in relatively thin layers of these compounds are highly desirable. Here, using full-field electromagnetic optical simulations, we demonstrate that a monolayer of resonant-size BiVO4 spheres can provide enhancement up to a factor of two in solar light absorption relative to dense planar layers. In this monolayer, BiVO4 spheres do not need to be interconnected; therefore, such monolayers are flexible and their fabrication...
An Artificial Neural Networks Model for Predicting Permeability Properties of Nano Silica-Rice Husk Ash Ternary Blended Concrete
, Article International Journal of Concrete Structures and Materials ; Volume 7, Issue 3 , September , 2013 , Pages 225-238 ; 22341315 (ISSN) ; Khaloo, A ; Iraji zad, A ; Abdul Rashid, S ; Sharif University of Technology
Korea Concrete Institute
2013
Abstract
In this study, a two-layer feed-forward neural network was constructed and applied to determine a mapping associating mix design and testing factors of cement-nano silica (NS)-rice husk ash ternary blended concrete samples with their performance in conductance to the water absorption properties. To generate data for the neural network model (NNM), a total of 174 field cores from 58 different mixes at three ages were tested in the laboratory for each of percentage, velocity and coefficient of water absorption and mix volumetric properties. The significant factors (six items) that affect the permeability properties of ternary blended concrete were identified by experimental studies which were:...
Examination of a solar desalination system equipped with an air bubble column humidifier, evacuated tube collectors and thermosyphon heat pipes
, Article Desalination ; Volume 397 , 2016 , Pages 30-37 ; 00119164 (ISSN) ; Behshad Shafii, M ; Sharif University of Technology
Elsevier
Abstract
In this paper, the performance of a novel HDH solar desalination system equipped with a combination of heat pipe (HP), evacuated tube collector (ETC) and air bubble column humidifier is experimentally investigated. This novel HDH system uses advantages of ETC-HP as a highly efficient thermal absorption and conductor device, and at the same time employs the advantages of an air bubble column humidifier, i.e. high interface area and effective mixing in order to heat the water and humidify the air, respectively. The effects of various parameters including incoming air flow rate into the humidifier, initial depth of water in the humidifier, and adding fluids such as oil and water in the space...
A comprehensive energy supply model in an office building based on the reference energy system
, Article International Journal of Sustainable Energy ; Volume 35, Issue 1 , 2016 , Pages 88-102 ; 14786451 (ISSN) ; Rasekhi, H ; Fathi, A ; Sharif University of Technology
Taylor and Francis Ltd
Abstract
In the last decade, technological innovations have resulted in considering distributed generation with heat recovery capability in addition to centralised generation. This work aims to develop a comprehensive model analysing techno-economic parameters of energy supply in an office building. The energy model is developed on the basis of the reference energy system with the linear programming technique. The objective function is the annual value of total costs of the energy supply system. The results of the model for the building of Sharif Energy Research Institute indicate that the most appropriate generation technology is an internal combustion engine of 461 kW and a water boiler of 152 kW....
Biodegradable polyurethane acrylate/HEMA-grafted nanodiamond composites with bone regenerative potential applications: Structure, mechanical properties and biocompatibility
, Article RSC Advances ; Volume 6, Issue 11 , 2016 , Pages 8743-8755 ; 20462069 (ISSN) ; Shojaei, A ; Abdekhodaie, M. J ; Sharif University of Technology
Royal Society of Chemistry
Abstract
The present study demonstrates HEMA-grafted nanodiamond (ND-HEMA)/acrylate-terminated polyurethane-acrylate diluents (APUA) composites as promising materials for bone implant applications. Neat APUA and APUA composites containing ND-HEMA at different loadings up to 2 wt% were prepared by an in situ polymerization method. Morphological analysis demonstrated that ND-HEMAs were actually in the form of tightly bound aggregates which led to formation of big agglomerates at a concentration of 2 wt%. It was also suggested that ND-HEMAs were preferentially localized in the continuous soft domain of APUA; however it interacted by both soft and hard domains. Moreover, ND-HEMAs caused considerable...
Low-temperature gas-solid carbonation of magnesia and magnesium hydroxide promoted by non-immersive contact with water
, Article RSC Advances ; Volume 6, Issue 92 , 2016 , Pages 89655-89664 ; 20462069 (ISSN) ; Chen, J ; Haghighatlari, M ; Åbacka, J ; Zevenhoven, R ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
From gas-solid carbonation studies and product characterization by XRD, carbon elemental analysis, and TG-FTIR profiling of evolved CO2, the presence of water vapour at high relative humidity (>25% RH) was shown to cause a drastic acceleration in the rate of CO2 absorption into MgO and Mg(OH)2 producing magnesite and hydrocarbonated precursors. From thermogravimetric experiments in the vicinity of the dew point, carbonation was shown to proceeded in steps triggered by spontaneous condensation (and re-evaporation) of water. Almost complete conversion to magnesite (MgCO3) and/or hydromagnesite [HM = 4MgCO3·Mg(OH)2·4H2O] was observed in a few hours under rather mild conditions of pressure (PCO2...
Improving the visible light photoelectrochemical activity of synthesized TiO2 nanotube arrays in an organic electrolyte containing sodium carbonate with doping by copper: Via single-step anodization
, Article New Journal of Chemistry ; Volume 41, Issue 19 , 2017 , Pages 10723-10730 ; 11440546 (ISSN) ; Yoozbashizadeh, H ; Sharif University of Technology
Royal Society of Chemistry
2017
Abstract
The main aim of this research is to improve the photocatalytic activity of TiO2 nanotubes by co-doping with copper and sodium for application in the water splitting process as a photoanode. The doping was performed simultaneously to the anodizing process through a single-step treatment. The synthesized TiO2 nanotube array (TNA) was characterized by applying FESEM (Field Emission Scanning Electron Microscopy), XRD (X-ray Diffraction), DRS (Diffraction Reflection Spectroscopy) and XPS (X-ray Photoelectron Spectroscopy) analyses. The results of XPS analysis proved the presence of copper with valence (2+) and carbon and sodium with valence (1+). Moreover, DRS tests showed a reduction in the band...
Exergetic and thermoeconomic analysis of a trigeneration system producing electricity, hot water, and fresh water driven by low-temperature geothermal sources
, Article Energy Conversion and Management ; Volume 157 , 2018 , Pages 266-276 ; 01968904 (ISSN) ; Arefi, A. R ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Performance of a small-scale trigeneration system driven by low-temperature geothermal sources for producing fresh water, heating (hot water) and electricity is investigated from thermodynamic and economic standpoints. This system, utilizing a single stage absorption heat transformer leads to an increase in heat source temperature to be used in single stage evaporation desalination process and also providing water heating. Furthermore, an organic Rankine cycle is used for electric power generation. The developed model is validated with available data and effects of decision variables namely geothermal source, absorber and condenser temperatures on energy and exergy efficiencies of the...
Synthesis of ethyl cellulose/aluminosilicate zeolite nanofibrous membranes for oil–water separation and oil absorption
, Article Cellulose ; Volume 26, Issue 18 , 2019 , Pages 9787-9801 ; 09690239 (ISSN) ; Jamshidifard, S ; ZabihiSahebi, A ; Abouchenari, A ; Darabi, M ; Irani, M ; Sharif University of Technology
Springer Netherlands
2019
Abstract
ZSM-5 (Seolite Sconoy Mobil) aluminosilicate zeolites synthesized by the hydrothermal method were incorporated into the hydrophobic ethyl cellulose (EC) nanofibrous membrane. The performance of synthesized nanofibers was investigated for a gravity driven oil–water separation. The synthesized ZSM-5 nanozeolites and EC/ZSM-5 composite nanofibers were characterized using XRD, FESEM, XPS, FTIR and AFM analysis. The permeability of EC/ZSM-5 5 wt% for oil in water mixture was in order of n-hexane (5170 ± 60 L/m2 h) > n-heptane (4600 ± 50 L/m2 h) > cyclohexane (4350 ± 35 L/m2 h) > pump oil (3780 ± 28 L/m2 h) > lubricating oil (3200 ± 25 L/m2 h) > motor oil (2980 ± 20 L/m2 h) with a separation...
Effects of Mica and Feldspar as partial cement replacement on the rheological, mechanical and thermal durability of self-compacting mortars
, Article Construction and Building Materials ; Volume 263 , December , 2020 ; Fard Samimi, M ; Mohammadi, F ; Talebitaher, P ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this experimental study, the impacts of replacing cement by Mica and Feldspar on rheological, mechanical and thermal durability of self-compacting mortars (SCMs) are investigated. The cement was partially replaced by Mica and Feldspar at the substitution rates of 10%, 20% and 30%. In general, 14 mix designs of SCMs were considered in two series with w/b ratios of 0.4 and 0.3. For assessment of rheological properties, mini-cone slump flow test and mini V-funnel tests were performed. The compressive strengths after 3, 7, 28 and 90 days of curing, and the 28-day flexural strength were obtained. All mixes were subjected to water absorption and sorptivity tests. For investigating the thermal...
Novel nanoporous superabsorbent hydrogel based on poly(acrylic acid) grafted onto salep: Synthesis and swelling behavior
, Article Starch/Staerke ; Volume 60, Issue 9 , 9 September , 2008 , Pages 467-475 ; 00389056 (ISSN) ; Soleyman, R ; Rezanejade Barajee, G ; Sharif University of Technology
2008
Abstract
Hydrogels of poly(acrylic acid) grafted onto salep with excellent water absorption and water retention abilities under neutral conditions were successfully synthesized for the first time and employed for different applications. The effect of reaction variables to achieve maximum swelling capacity was investigated. In our procedure, ammonium persulfate (APS) as a water-soluble initiator and methylenebisacrylamide (MBA) as a suitable crosslinking agent were used and the best synthesis conditions described. The structure of the final product was confirmed by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy SEM and TGA analysis and a mechanism for superabsorbent...
A study of mechanical and microstructures properties of autoclaved aerated concrete containing nano-graphene
, Article Journal of Building Engineering ; Volume 43 , 2021 ; 23527102 (ISSN) ; Pachideh, G ; Salimbahrami, S. B ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In recent years, the autoclaved aerated concrete (AAC) has been widely used in the building construction industry, especially for construction of infill walls. However, the AAC suffers from several drawbacks such as low compressive and tensile strength, high water absorption as well as insufficient resistance against impacts. To address such issues, this study evaluates the mechanical properties of the AAC blocks in which, the cement has been replaced with nano-graphene. For this purpose, various replacement ratios (0.2, 0.4, and 0.8) were selected and different tests such as compressive and tensile strength (cylindrical specimens with the size of 10 × 20 cm), impact resistance and water...
Reduction of cement consumption by the aid of silica nano-particles (investigation on concrete properties)
, Article Journal of Civil Engineering and Management ; Volume 18, Issue 3 , 2012 , Pages 416-425 ; 13923730 (ISSN) ; Hosseini, P ; Sharif University of Technology
2012
Abstract
In this study, effects of replacing cement with colloidal amorphous silica nano-particles have been experimentally investigated on the physical and mechanical properties, durability and microstructure of concrete. Experimental results include workability, fresh concrete density, and hardened concrete properties like compressive strength at different ages of 3, 7, and 28-days, and also 28-days splitting tensile strength. Furthermore, influence of silica nano-particles on durability and microstructure of concrete for 28-days specimens was tested by conducting water absorption test, Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Analysis (EDAX), respectively. In order to study...