Papers by Masoud Jamshidi
The present work described the influence of polymer admixture (i.e. polymer latexes) contents on ... more The present work described the influence of polymer admixture (i.e. polymer latexes) contents on the physical/mechanical properties of latex modified concretes (LMCs). At the first step, the optimum water to cement ratio was determined for a LMC concrete according to the results of compressive strength. Afterwards, six latexes were investigated as admixture for LMCs at 10% of latex content. Their physical and mechanical properties including compressive strength, flexural strength, splitting tensile strength and capillary water absorption was evaluated. Finally, two latexes which were better in LMCs general properties (i.e. Acrylic and Co-polymer Acrylic) were incorporated at 5 and 15% of latex contents to concrete. The result have shown that the increase in the amount of latex content decreased the compressive strength, but the other properties including flexural strength and split tensile strength were improved. Also, an improvement in barrier efficiency for water absorption of LMC...
Polymer concretes (PC) were introduced to building and construction industry more than 50 years a... more Polymer concretes (PC) were introduced to building and construction industry more than 50 years ago. Gradually, they became a suitable substitute for concrete structures; however, their application was shortly diminished due to the higher costs. In this research a homemade cost-quality effective resin (unsaturated polyester) is used as binder in the polymer concrete production. Laboratory specimens made and evaluated for physical/mechanical tests. A comparative study was performed on the polymer concrete specimens, the ordinary Portland cement concrete (normal concrete) and the durable concrete specimens. It was found that the PC materials show much better physical/mechanical properties than the durable concretes.
The aim of this study was to investigate the flexural behavior of engineered cementitious composi... more The aim of this study was to investigate the flexural behavior of engineered cementitious composites (ECCs) reinforced by cellulose pulp (CP) and cellulose microfibers (CMF). The reinforcements were obtained from chemical-mechanical treatments of Kraft paper and used in ECC mix design. Results showed that cement reinforced by CP exhibited a strain-hardening behavior in the three-point bending test, while CMF led to a brittle behavior in cement composites. Moreover, different hybrid combinations of polyvinyl alcohol (PVA) and CMF achieved quite a high strength while maintaining a high level of flexural toughness. A combination of 0.5 vol% CMF and 1.5 vol% PVA resulted in a significant increase in flexural toughness and a slight improvement in flexural strength. The properties of this hybrid composite were comparable with one containing 2 vol% of PVA fiber.
Sulfate attack and its effects are important from both scientific and industrial viewpoints. It i... more Sulfate attack and its effects are important from both scientific and industrial viewpoints. It is perceived that cements containing pozzolan have better performance in sulfate solutions, since the pozzolanic reactions reduce the quantity of Calcium hydroxide and increase Calcium silicate hydrate. This paper investigates the physical/mechanical properties of concretes made by blended cement containing Tuff natural pozzolan, and Portland cement. The microstructure of mortars under sulfate attack is studied using SEM analysis and reaction products are characterized using EDS analysis. The results suggest that, contrary to previous opinions, mortars containing pozzolan show more expansion and unsatisfactory performance in sulfate solution.
Journal of Adhesion Science and Technology
ABSTRACT In this research, the adhesion of polypropylene (PP) fibers to cementitious matrix has b... more ABSTRACT In this research, the adhesion of polypropylene (PP) fibers to cementitious matrix has been investigated and the chemical bonding and mechanical interlocking between PP fiber and hardened cement paste has been studied. Furthermore, thermodynamic work of adhesion and loss-function (dissipation energy) has been calculated in the PP-cement matrix model system. To investigate the work of adhesion, the pull-out test has been used. Also, the surface free energy and contact angle of the PP monofilaments and cement matrix have been measured using a tensiometer and the fiber–cement interfacial interactions and thermodynamic work of adhesion and loss-function were calculated. Scanning electron microscopy (SEM) analysis was used to study the fiber–cement matrix interfacial transition zone (ITZ). The results showed that the application of theories of polymer–polymer adhesion in fiber–cement matrix systems was feasible. To verify the accuracy of the method, the adhesion of two other fibers (nylon 6,6 and acrylic polymer) was studied.
Construction and Building Materials
Abstract In this paper, the effect of surface modification of a carbon textile on the flexural be... more Abstract In this paper, the effect of surface modification of a carbon textile on the flexural behavior of the textile reinforced fine aggregate concretes was investigated. Three different surface modifying agents (i.e. styrene butadiene latex, hydrophilic oil and epoxy resin) were applied as coating on the carbon textiles at different weight ratios (i.e. 35, 70, and 100% by weight of the textile). The four point bending test was carried out on the samples. It was found that the textile surface modification led to an increase in the ductility of the textile reinforced concretes (TRCs). Utilizing the latex and oil coated textile reduced the post cracking strengths of the TRC samples while the epoxy coated textile led to a considerable increase in the post cracking strength (i.e. in the range of 72–190%). It was also found that the flexural toughness of the epoxy coated textile reinforced concrete improved in the range of 250–780% compared to the uncoated textile reinforced concrete. Meanwhile, it was found that in order to improve the flexural strength and toughness of the TRCs, it is more effective to apply surface modification to the textiles instead of using higher contents of reinforcing textiles. Finally, the interfacial transition zone (ITZ) of the textile and cement based matrix in all the samples was characterized using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy.
Journal of Composite Materials
In this study, multi-walled carbon nanotubes (MWCNTs) were functionalized by both sulfuric/nitric... more In this study, multi-walled carbon nanotubes (MWCNTs) were functionalized by both sulfuric/nitric acids and amino acids to form COOH and NH2/COOH/OH groups on their surface, respectively. The functionalized MWCNTs were characterized by Fourier Transform Infrared Spectroscopy, titration test, thermal gravimetric analysis, and solvent stability test. The results revealed that in each method, the functional groups were successfully attached to the surface of nanotubes. Acid treatment grafted more oxygen-containing groups compared to commercial carboxylated MWCNTs. The amino acid functionalized MWCNTs indicated improved stability in different solvents compared to raw and acid treated MWCNTs. These functionalized MWCNTs were incorporated into epoxy resin and the properties of the nanocomposites were evaluated by scanning electron microscopy, tensile test, dynamic mechanical thermal analysis, differential scanning calorimetry, and thermogravimetric analysis. The morphology of the nanocomp...
Civil Engineering Journal
Nowadays, the advantages of short fibers as reinforcement in cement based materials are well know... more Nowadays, the advantages of short fibers as reinforcement in cement based materials are well known. In this paper, the effect of hybridization of short polypropylene (PP) and carbon fibers on flexural properties of a fine aggregate concrete has been investigated. Samples with dimensions of containing 2 vol% of the polypropylene and carbon fibers with 6 and 8mm length were made. The PP to carbon fiber proportion in the samples were selected as 100:0, 75:25, 50:50, 25:75 and 0:100. A four-point bending test was carried out on all the samples to investigate the flexural behaviour. It was found that the addition of carbon fibers significantly increases the flexural load (i.e. 260%). The application of PP fibers leads to a 2590% increase in the toughness compared to the control sample. It was also found that the sample with carbon to PP ratio of 75/25 shows the optimum results and it leads to 190% and 2070% increment in the flexural load and toughness, respectively, in comparison to the...
Progress in Organic Coatings
Abstract Today, photo-catalysts are considered for purification of air and wastewater from organi... more Abstract Today, photo-catalysts are considered for purification of air and wastewater from organic pollutants. The method is based on photo oxidation of pollutants and their decomposition to CO2 and mineral products. The aim of this research is the investigation of changes in the mechanical properties of acrylic pseudo-paints contained nano TiO2 and PAni/TiO2 nanocomposite after photocatalytic degradation of Benzene under UV irradiation. For this purpose, different contents of nano-catalysts (i.e. 1, 2, and 5 wt.%) were applied to acrylic latex. In some samples 10 wt.% of TiO2 pigment and 5 wt.% of CaCO3 were also used to produce pseudo paint samples. The photocatalytic oxidation (PCO) activity of the samples was measured using gas chromatography (GC) analysis. The tensile properties (i.e. tensile strength, modulus, toughness, and elongation at break) of the samples were evaluated before and after PCO activity. The morphology of the samples was characterized using scanning electron microscopy (SEM). The overall color changes in the pseudo paints as a criteria for determining the photo degradation of the samples due to PCO activity were measured. A good correlation between GC results and the mechanical properties was found. Results showed that at 2 wt.% of nano TiO2 maximum amounts of the mechanical and photocatalytic properties were achieved. It was also found that by introducing PAni/TiO2 to the acrylic films, the mechanical properties were decreased considerably compared to the nano TiO2 containing samples. It was attributed to the crystalline nature of PAni or immiscibility of PAni and acrylic matrix which was confirmed by DMTA results.
Journal of Central South University
Partially replacing polyvinyl-alcohol (PVA) fibers with polypropylene (PP) fibers in strain-harde... more Partially replacing polyvinyl-alcohol (PVA) fibers with polypropylene (PP) fibers in strain-hardening cementitious composites (fiber hybridization) modify certain mechanical properties of these materials. The hybridization based on the introduction of low-modulus hydrophobic polypropylene fibers improves the ductility and the strain-hardening behavior of the cementitious composites containing polyvinyl-alcohol fibers of different types (PVA-SHCC). Pull-out tests indicate that adding PP fibers increases the energy capacity of the hybrid composite with respect to the material containing only PVA fibers under tensile loading, and PP-fiber geometry (i.e., section shape and length) is a key factor in enhancing the strain capacity.摘要在应变硬化水泥基复合材料(纤维杂交)中, 用聚丙烯部分取代聚乙烯醇(PVA)纤维, 可以改善材料的力学性能。 通过引入低模量、 疏水聚丙烯纤维, 提高聚乙烯醇纤维水泥复合材料(PVA-SHCC)的拉伸性和应变硬化性能。 拉伸试验结果表明, 加入聚丙烯纤维增强了掺杂复合材料的载荷拉伸性能。 聚丙烯纤维的几何形状(即截面形状和长度)是提高复合材料应变能力的重要因素。
Environmental Technology
ABSTRACT Carbon-doped titanium dioxide photocatalyst with improved performance in visible light w... more ABSTRACT Carbon-doped titanium dioxide photocatalyst with improved performance in visible light was prepared via the typical sol–gel method. Microcrystalline cellulose (MCC) was used as carbon elements source. The prepared pure and carbon-doped TiO2 samples were calcined at 400–650°C in air and the effect of annealing temperature on the stability of carbon ions was investigated. EDX analysis showed the presence of 5.66 wt.% carbon atoms in TiO2 nanoparticles formed on MCC, which was attributed to the doping of carbon atoms in TiO2 lattice. Carbon doping was also confirmed by Raman spectroscopy. According to the UV–VIS DRS analysis, the band gap of TiO2 particles decreased from 2.96 to 2.71 eV in pure and carbon-doped TiO2, respectively. Therefore the visible light absorbance increased to 15.05% compared to 0% absorbance in pure TiO2. The heat treatment of carbon-doped TiO2 nanostructures showed that carbon element could escape from the O–Ti–O lattice at temperatures higher than 600°C. According to the SEM images, synthesis of TiO2 in presence of MCC also limited the growth of TiO2 nanoparticles and controlled the morphology and aggregation of nanoparticles. Carbon doping improved the photocatalytic performance of TiO2 photocatalyst compared to the pure nanoparticles in degradation of methylene blue in the aqueous phase. Carbon-doped TiO2 attained the efficiency of 56.25%, 51.18% and 62.95% under UV, visible and solar lights, respectively, compared to 28.43%, 6.36% and 33.65% related to the pure TiO2. GRAPHICAL ABSTRACT
Iranian Journal of Orthodontics
The Journal of The Textile Institute
Abstract This paper investigates the effect of hydrophilic polyvinyl alcohol (PVA) fiber’s conten... more Abstract This paper investigates the effect of hydrophilic polyvinyl alcohol (PVA) fiber’s content (1.2–2.0% volume of composite) on the flexural behavior of engineered cementitious composites (ECC) materials. Different parameters of flexural behavior such as strength at first-cracking and post-cracking stages, deflection at ultimate load, toughness indices according to ASTM 1018, flexural modulus, and energy absorption were determined. Test results showed that the flexural strength and flexural modulus of composites significantly increases by increment in fiber content. However, flexural strength of composites varies from 8.5 to 14 MPa depending on amount of PVA fibers. The toughness indices, deflection at max load and energy absorption were decreased by further increase in the fiber content from 1.6 to 2%. It was indicated that there was an indirect relationship between flexural strength and ductility of composite in higher amount of fiber content.
Journal of Applied Polymer Science
In this research, methylene diphenyl diisocyanate (MDI) was added to an acrylonitrile–butadiene r... more In this research, methylene diphenyl diisocyanate (MDI) was added to an acrylonitrile–butadiene rubber (NBR) compound as an additive, and its effects on the vulcanization of the rubber investigated. For this purpose, MDI was added at different concentrations (5, 10, and 20 phr) to the rubber compound. The rubber properties, including the rheometry and tensile strength, were investigated. Differential scanning calorimetry and swelling tests were used to assess the vulcanization mechanism and chemical reactions in the presence of MDI. Finally, Fourier transform infrared spectroscopy analysis was used to study the chemical structure of the NBR–MDI cured compounds. We found that MDI played a more important role than the additive in the NBR compound. It acted as a covulcanizing agent along with the sulfur groups. The 10 phr MDI content was found to be the optimum content for achieving the best NBR–MDI properties. This content increased the crosslinking density of the compound and decreased the swelling of NBR in toluene. We also found that MDI adsorbed the accelerator agents and sulfur groups, so it decreased the rate of vulcanization, especially at early ages. Furthermore, it reacted with NBR and produced strong urea (i.e., NH—CO—NH) and thiourethane groups (i.e., S—CO—NH), and this increased NBR's structural strength. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2017
Construction and Building Materials
Abstract The use of hybrid short fibers in a suitable combination as reinforcement for cement bas... more Abstract The use of hybrid short fibers in a suitable combination as reinforcement for cement based materials has attracted widespread attention because of their benefits compared to mono fiber reinforcement in recent years. This paper provides a review of recent developments on the area of the cement-based composites reinforced by hybrid short fibers. The aim of paper is to represent the effects of hybridization by elaborating upon the chemical, physical and mechanical properties of fibers on the performance of fiber reinforced concretes (FRC). This provides a summary of the existing knowledge about the successful use of different hybrid forms such as combination of steel, polymer and natural fibers in cementitious composites. Different types of hybrid system depending on fiber type are classified and reviewed. Furthermore, the physical and mechanical properties of resultant composites are also presented. Generally, inclusion of fibers in concrete as hybrid forms, improves many of its engineering properties such as toughness, ductility, energy absorption capacity and durability performance in comparison with mono fiber reinforcement.
Journal of Applied Polymer Science, 2016
The aim of this work is to produce a photocatalytic pseudo-paint for benzene removal from air and... more The aim of this work is to produce a photocatalytic pseudo-paint for benzene removal from air and find the role of TiO2 nanoparticles, TiO2 pigment, and CaCO3 extender on photocatalytic performance of this paint along with their role on stress–strain behavior after ultraviolet (UV) exposure. For this purpose, TiO2 nanoparticles were dispersed into an indoor paint resin (i.e., copolymer acrylic–styrene). The impact of main components of the paint on photocatalytic oxidation (PCO) rate of benzene was studied. It was found that dispersion of nanoparticles had the most dramatic effect on photo activity of nanocomposite. TiO2 pigment generally increased PCO rate and also made the paint more stable under tensile stress. CaCO3 may increase and/or decrease PCO of benzene, whether there is pigment in the formulation or not. However, it does not generally contribute to making the formulation resistant to UV exposure. Nanoparticles bring PCO and mechanical strength into the paint, but fail to strengthen the composite against UV deterioration. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44447.
Journal of Applied Polymer Science, 2016
In this study, the effects of multi-walled carbon nanotubes (MWCNT), and its hybrids with iron ox... more In this study, the effects of multi-walled carbon nanotubes (MWCNT), and its hybrids with iron oxide (Fe2O3) and copper oxide (CuO) nanoparticles on mechanical characteristics and thermal properties of epoxy binder was evaluated. Furthermore, simultaneous effects of using MWCNT with TiO2 as pigment and CaCO3 as filler for epoxy composites were determined. To investigate effects of nano- and micro-particles on epoxy matrix, the samples were evaluated by TGA and DTA. It was found that the hybrid of MWCNT with nano metal oxides caused considerable increment in the tensile and flexural properties of epoxy samples in comparison to the single MWCNT containing samples at the same filler contents. Significant improvement in the thermal conductivity of epoxy samples was obtained by using TiO2 pigment along with MWCNT. The TiO2 pigment also caused considerable improvement in mechanical properties of the epoxy matrix and the MWCNT containing nanocomposite. The best mechanical and thermal properties of epoxy nanocomposites were obtained at 1.5 wt % of MWCNT and 7 wt % of TiO2 that it should be attributed to particle network forming of the particles which cause better nano/micro dispersion and properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43834.
The advantages of staple fibers as reinforcement in cement based composites are well known. The i... more The advantages of staple fibers as reinforcement in cement based composites are well known. The interaction between fiber and cementitious matrix is effective in mechanical properties of composites. Engineered cementitious composite (ECC), is a new type of high performance fiber reinforced cementitious composites with high ductility. It is used for seismic applications, impact and blast resistant structures. The flexural strength of these composites is very high. This is why they were named as bendable concrete. Polyvinyl alcohol fibers are introduced as the best reinforcement for ECCs, but unfortunately they are not produced in our country. In this paper, a commercial ECC mix design is used and the feasibility of application of low modulus polymeric fibers instead of PVA fibers is investigated. For this reason, the three point bending tests are carried out on ECC sheets containing 2% by volume of nylon 66 fibers with two different lengths. Results show that the flexural toughness of ECC specimens with 12mm nylon 66 fibers is increased more than 130 times in comparison to the control specimen. Furthermore, the flexural behavior of ECC samples is improved with increase in fiber length.
Applied Surface Science, 2016
Abstract Fiber to rubber adhesion is an important subject in rubber industry. It is well known th... more Abstract Fiber to rubber adhesion is an important subject in rubber industry. It is well known that surface treatment (i.e. physical, mechanical and chemical) is an effective method to improve interfacial bonding of fibers and/or fabrics to rubbers. UV irradiation is an effective method which has been used to increase fabric-rubber interfacial interactions. In this research UV assisted chemical modification of PET fabrics was used to increase PET to nitrile rubber (NBR) adhesion. Nitrile rubber is a perfect selection as fuel and oil resistant rubber. However it has weak bonding to PET fabric. For this purpose PET fabric was carboxylated under UV irradiation and then methylenediphenyl diisocyanate (MDI) was grafted on carboxylated PET. The chemical composition of the fabric before and after surface treatment was investigated by X-ray photoelectron spectroscopy (XPS). The sectional morphology of the experimental PET fibers and the interface between rubber compound and PET fabric was studied using scanning electron microscope (SEM). The morphology and structure of the product were analyzed by an energy dispersive X-ray spectrometer (EDX). FTIR-ATR and H NMR analysis were used to assess surface modifications on the PET irradiated fabrics.
Iranian Polymer Journal, 2016
In this study, acrylic-based nanocomposites containing different contents of multi-walled carbon ... more In this study, acrylic-based nanocomposites containing different contents of multi-walled carbon nanotubes (MWCNTs) and metal oxide nanoparticles (i.e., TiO2, CuO and Fe2O3) were fabricated by solvent mixing method. The thermal conductivity of these samples was evaluated. The results indicated that the thermal conductivity of all fabricated samples was significantly improved even at small loading of MWCNTs. It was found that the thermal conductivity was enhanced by increase in MWCNTs content up to 5 wt%. Similarly, the metal oxide nanoparticles caused up to 75 % increment in thermal conductivity at 1.5 wt% of their loading in acrylic film. Contrary to expectations, the thermal conductivity of acrylic film was more increased by nanometal oxides (i.e., TiO2, CuO and Fe2O3) than MWCNTs. The effect of hybridizing of nanometal oxide particles (1.5 wt%) and MWCNTs (1.5 wt%) on thermal conduction was investigated as well. It was found that hybridizing improved thermal conductivities by about 85, 94 and 97 % for Fe2O3, TiO2 and CuO, respectively. Finally, the effects of TiO2 pigment and CaCO3 extender on the thermal conductivity of acrylic polymer and nano-TiO2 acrylic composites were studied. It was found that TiO2 could increase considerably thermal conduction of its acrylic films and acrylic nanocomposites.
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Papers by Masoud Jamshidi