Strength and microstructure characteristics of concrete with different grade exposed to standard fire

2020 ◽  
Vol 11 (3) ◽  
pp. 261-287
Author(s):  
Daniel Paul Thanaraj ◽  
Anand N. ◽  
Prince Arulraj
Keyword(s):  
Elevated Temperature ◽  
Residual Strength ◽  
Thermo Gravimetric Analysis ◽  
International Standards ◽  
Simple Relationship ◽  
Gravimetric Analysis ◽  
Content Type ◽  
Strength Grade ◽  
Standard Fire ◽  
Heated Concrete

Purpose The purpose of this study is to investigate the effect of standard fire on the strength and microstructure properties of concrete with different strength grades. Design/methodology/approach Different strength grades of concrete used for the investigation are M20, M30, M40 and M50. An electrical bogie hearth furnace was developed to simulate the International Standards Organization 834 standard fire curve.Concrete samples were subjected to high temperatures of 925, 1,029, 1,090 and 1,133°C for the duration of 1, 2, 3 and 4 h, respectively, as per standard fire curve. Compressive strength, tensile strength, thermal crack pattern and spalling of heated concrete specimens were evaluated by experimental investigation. Scanning electron microscopy and thermo-gravimetric analysis were performed to investigate the microstructure properties of heated concrete specimens. Findings Test results indicated reduction in the strength and changes in the microstructure properties of concrete exposed to elevated temperature. The degree of weight and the strength loss were found to be higher for concrete with higher grades. An empirical relation is proposed to determine the residual strength of concrete with different strength grade using regression analysis. Social implications Results of this research will be useful for the design engineers to understand the behavior of concrete exposed to elevated temperature as per standard fire. Originality/value When concrete is exposed to elevated temperature, its internal microstructure changes, thereby strength and durability of concrete deteriorates. The performance of concrete with different strength grade exposed to standard fire is well understood. This research’s findings will be useful for the designers to understand more about fire resistance of concrete. A simple relationship is proposed to determine the residual strength of concrete exposed to various durations of heating.

Experimental investigation of mechanical properties and physical characteristics of concrete under standard fire exposure

2019 ◽  
Vol 17 (5) ◽  
pp. 878-903 ◽  
Author(s):  
Daniel Paul Thanaraj ◽  
Anand N. ◽  
Prince Arulraj
Keyword(s):  
Experimental Investigation ◽  
Weight Loss ◽  
Flexural Strength ◽  
Residual Strength ◽  
Empirical Relationship ◽  
Empirical Relation ◽  
Flexural Behavior ◽  
Content Type ◽  
Strength Grade ◽  
Standard Fire

Purpose This paper aims to explain the influence of Standard Fire as per ISO 834 on the strength and microstructure properties of concrete specimens with different strength grade. Design/methodology/approach The strength grades of concrete considered for the experimental investigation were Fck20, Fck30, Fck40 and Fck50. The specimens were heated up to 1, 2, 3 and 4 h as per standard fire curve. Effect of elevated temperature on compressive and flexural behavior of specimens with various strength grades was examined. Effects of age of concrete, weight loss, surface characteristics and thermal crack pattern were also investigated. Findings Experimental investigation shows that strength grade, duration of exposure and age of concrete are the key parameters affecting the residual strength of concrete. For the beams exposed to 3 and 4 h of heating, the residual flexural strength was found to be so insignificant that the specimens were not able to even sustain their own weight. The loss in compressive and flexural strength of Fck50 concrete specimens heated up to 1 h were found to be 26.41 and 86.03 per cent of the original unheated concrete, respectively. The weight loss was found to be more for higher grade concrete specimens, and it was about 8.38 per cent for Fck50 concrete. Regression analysis was carried out to establish the empirical relation between residual strength and grade of concrete. Scanning electron microscopy and thermogravimetric analysis were carried out to examine the damage level of fire-affected concrete specimens. Originality/value Empirical relationship was developed to determine the residual strength of concrete exposed to elevate temperature, and this will be useful for design applications. This database may be useful for identifying member strength of reinforced beams subjected to various durations of heating so that suitable repair technique can be adopted from the available database. It will be useful to identify the proper grade of concrete with regard to fire endurance, in the case of concrete under compression or flexure.

scholarly journals Preparation and characterisation of modified reclaimed asphalt using nanoemulsion acrylate terpolymer

2019 ◽  
Vol 48 (5) ◽  
pp. 363-374 ◽  
Author(s):  
Abdelrahman Moukhtar Naser ◽  
Hamada Abd El - Wahab ◽  
Mohamed Abd El Fattah Moustafa El Nady ◽  
Abdelzaher E.A. Mostafa ◽  
Long Lin ◽  
...  
Keyword(s):  
Hot Mix Asphalt ◽  
Fourier Transforms ◽  
Thermo Gravimetric Analysis ◽  
Thermoplastic Elastomer ◽  
Warm Mix Asphalt ◽  
Gravimetric Analysis ◽  
Content Type ◽  
Reclaimed Asphalt ◽  
Asphalt Paving ◽  
Modified Binder

Purpose This paper aims to investigate the best methods of utilisation of reclaimed asphalt pavements (RAP) in Egypt, to determine the effect of using 100% RAP instead of using virgin aggregates and asphalt; investigate the effect of thermoplastic elastomer polymer as asphalt modifier; and also improve the mechanical and physical characteristics and consequently improving the quality of asphalt paving, increasing service life of asphalt-paving and reducing costs. Design/methodology/approach Nano acrylate terpolymers were prepared with different % (Wt.) of and were characterised by Fourier transforms infrared (FTIR), for molecular weight (Mw), by thermo gravimetric analysis (TGA) and by transmission electron microscopy (TEM). A 4% (Wt.) of the prepared nanoemulsion terpolymer was mixed with virgin asphalt as a polymer modifier, to improve and reuse of the RAP. The modified binder was tested. The tests conducted include penetration, kinematic viscosity, softening point and specific gravity. Application of Marshall mix design types; hot mix asphalt (HMA), warm mix asphalt (WMA) and cold in place recycled (CIR). Four different mix designs used; control mix contained virgin asphalt by HMA, and the other three mix designs were polymermodified asphalt sample by HMA, WMA and CIR. Findings The research results showed that using 4 Wt.% of the prepared nanoemulsion terpolymer to produce hot mix asphalt (HMA) and warm mix asphalt (WMA) achieved higher stability compared to the control mix and cold in place recycled (CIR). Research limitations/implications This paper discusses the preparation and the characterisation of nanoemulsion and its application in RAPs to enhance and improve the RAP quality. Practical implications Nano-acrylate terpolymer can be used as a new polymer to modify asphalt to achieve the required specifications for RAP. Originality/value According to the most recent surveys, Europe produced 265 tonnes of asphalt for road applications in 2014, while the amount of available RAP was more than 50 tonnes. The use of RAP in new blended mixes reduces the need of neat asphalt, making RAP recycling economically attractive.

Synthesis, characterization and tribological behavior of oleic acid-capped core-shell lanthanum borate-SiO2 composites

2014 ◽  
Vol 66 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Zhengfeng Jia ◽  
Yan-qiu Xia ◽  
Xin Shao ◽  
San-ming Du
Keyword(s):  
Oleic Acid ◽  
Tribological Properties ◽  
Friction And Wear ◽  
Thermo Gravimetric Analysis ◽  
Core Shell ◽  
Gravimetric Analysis ◽  
Content Type ◽  
Aisi 1045 Steel ◽  
Aisi 1045 ◽  
1045 Steel

Purpose – The purpose of this paper is to investigate the tribological properties of poly-alpha-olefin (PAO) with nano/microstructure core-shell lanthanum borate-SiO2 composites (OCLS). Design/methodology/approach – Oleic acid-capped core-shell lanthanum borate-SiO2 composites were synthesized by an easy way. The composites were characterized by means of Fourier transform-infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermo gravimetric analysis (TGA). The friction and wear behaviors of the quenched AISI 1045 steel specimens sliding against AISI 52100 steel under the lubrication of PAO containing OCLS were comparatively investigated with PAO containing SiO2 additive on an Optimol SRV reciprocating friction and wear tester. On the other hand, the tribological properties of the PAO containing OCLS were also investigated on four-ball tester. Findings – The diameter of OCLS was about 20 nm, and the thickness of the SiO2 shell was less than 5 nm. The ratio of oleic acid (OA) is about 15 percent. The PAO containing OCLS possesses much better tribological properties than that of pure PAO and PAO containing SiO2 additive. Originality/value – The PAO+OCLS possess a better friction reducing and antiwear properties than pure PAO. The new additive can improve the tribological ability of machinery.

Cellulose nanocrystals reinforced shape memory polymer cardiovascular stent

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yu Chen ◽  
Irina Tatiana Garces ◽  
Tian Tang ◽  
Cagri Ayranci
Keyword(s):  
Additive Manufacturing ◽  
Shape Memory ◽  
Thermo Gravimetric Analysis ◽  
Modulated Dsc ◽  
Recovery Ratio ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Ratio Measurement ◽  
Content Type

Purpose The purpose of this paper is to demonstrate an innovative, fast and low-cost method to fabricate customized stents using polyurethane-based shape memory polymers composite reinforced by cellulose nanocrystal (CNC), achieved by a commercial desktop extrusion-based additive manufacturing (EBAM) device. Design/methodology/approach The composite filament for printing the stents was prepared by a two-step melt-compounding extrusion process. Afterward, the stents were produced by a desktop EBAM printer. Thermal characterizations, including thermo-gravimetric analysis (TGA) and modulated differential scanning calorimetry (modulated DSC), were conducted on stent samples and filament samples, respectively. Then the stents were programmed under 45°C. Recovery characterizations, including recovery force and recovery ratio measurement, were conducted under 40°C. Findings TGA results showed that the materials were stable under the printing temperature. Modulated DSC results indicated that, with the addition of CNCs, the glass transition temperature of the material dropped slightly from 39.7°C at 0 Wt.% CNC to 34.2°C at 7 Wt.% CNC. The recovery characterization showed that the stents can exert a maximum recovery force of 0.4 N/mm when 7 Wt.% of CNCs were added and the maximum recovery ratio of 35.8% ± 5.1% was found when 4 Wt.% of CNCs were added. The addition of CNC improved both the recovery ratio and the recovery force of the as-prepared stents. Originality/value In terms of recovery force, the as-prepared stents out-performed commercially available stents by 30 times. In addition, additive manufacturing offers more flexibility in the design and fabrication of customized cardiovascular stents.

scholarly journals New water-based flexographic ink based on new ter-polymer nano-particles as eco-friendly binders – Part II

2020 ◽  
Vol 49 (6) ◽  
pp. 473-482
Author(s):  
H. Abd El-Wahab ◽  
G.A. Meligi ◽  
M.G. Hassaan ◽  
L. Lin
Keyword(s):  
Water Resistance ◽  
Low Cost ◽  
Thermo Gravimetric Analysis ◽  
Gel Permeation Chromatography ◽  
Nano Particles ◽  
Gravimetric Analysis ◽  
Adhesion Properties ◽  
Content Type ◽  
Low Viscosity ◽  
Water Based

Purpose The purpose of this study is to prepare, characterise and evaluate nano-emulsions of ter-polymers of various compositions as eco-friendly binders for flexographic ink industry. Design/methodology/approach Various nano-emulsions of ter-polymers were prepared based on Vinyl acetate, Vinyl Versatate, butyl acrylate, acrylic acid and acrylamide monomers by means of a conventional seeded emulsion polymerisation technique, using K2S2O8 as the initiator. The characterisation of the prepared emulsions was performed using Fourier transform infrared, thermo-gravimetric analysis, gel permeation chromatography and transmission electron microscopy. A selection of co-polymers and ter-polymers were formulated with pigments and additional ingredients, as water-based flexographic inks. The inks were characterised for their rheological properties, pH, degree of dispersion, water-resistance and colour density. Findings It was found that the low viscosity of the prepared polymers may reduce the film thickness of the flexographic inks and may also increase the spreading of the ink on the surface. As a result, stable modified poly acrylate-based latex with improved physico-mechanical properties was obtained. The prepared latexes showed improved properties such as enhanced thermal stability and better water resistance. The effect of the emulsifier type on the properties of the resulting emulsion latexes and their corresponding films were investigated. Also, as the hydrophobic monomer increases, so does the colour density and increasing the binder ratio enhances the gloss values. The improving in gloss values were obtained and provide excellent adhesion properties for both the pigment particles and the base paper. Research limitations/implications The study focusses on the preparation of new water-based ter-polymer nano-particles and their use as eco-friendly binders for flexographic ink industry. Ink formulations based on other different type emulsion polymers could also be studied to assess the applicability of the ink formulation system found for other binders. Practical implications The ink formulations developed could find use in industrial-scale printing. Originality/value Eco-friendly environment and low-cost ink formulations for printing on paper substrates are novel.

Nacre-mimetic CH/MMT fabrication coating on PET fabric for improving anti-dripping performance

2020 ◽  
Vol 32 (6) ◽  
pp. 803-812
Author(s):  
Yinchun Fang ◽  
Xinhua Liu ◽  
Wenqing Fei
Keyword(s):  
Flame Retardant ◽  
Flame Retardancy ◽  
Thermo Gravimetric Analysis ◽  
Original Research ◽  
Gravimetric Analysis ◽  
Experimental Basis ◽  
Limiting Oxygen Index ◽  
Content Type ◽  
Pet Fabric ◽  
Assembly Method

PurposePET fiber is widely used in many fields, such as clothing and decorative materials. However, the high flammability and dripping problem restrict its applications. It is vital for PET fiber to overcome these two main drawbacks for practical applications.Design/methodology/approachIn this paper nacre-mimetic flame retardant coating of chitosan (CH) and Montmorillonite (MMT) was fabricated on PET fabrics through the layer-by-layer assembly method. The flame retardancy and anti-dripping performance of the treated PET fabric were investigated.FindingsThe results of limiting oxygen index (LOI) value and vertical burning test revealed the anti-dripping performance of PET fabrics which was greatly improved, while the flame retardancy has not been improved. The dripping phenomena was eliminated when the CH/MMT bilayers were over 5 BL. Thermo gravimetric analysis (TGA) results revealed that nacre-mimetic coated CH/MMT bilayers on PET fabrics would promote the char formation both under nitrogen atmosphere and under air atmosphere indicating the obviously condensed phase flame retardant action. scanning electron microscopy (SEM) images of the char residues revealed that coated PET fabrics would promote the formation of char.Research limitations/implicationsHowever, the char was an unstable char which would further combust to change the thermal degradation and combustion process of PET fabric. Though PET fabric coated by this CH/MMT nacre-mimetic system had no flame retardancy, the anti-dripping performance was greatly improved. This research would provide experimental basis for improving the anti-dripping performance for thermoplastic materials.Originality/valueThis research is the original research for the flame retardant treatment by fabrication nacre-mimetic CH/MMT coating on PET fabric, which has not been reported previously. This research would provide experimental basis for improving the anti-dripping performance for thermoplastic polymer fabrics.

Tribological behaviours of surface-modified serpentine powder as lubricant additive

2016 ◽  
Vol 68 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Yawen Zhang ◽  
Zhipeng Li ◽  
Jincan Yan ◽  
Tianhui Ren ◽  
Yidong Zhao
Keyword(s):  
Thermo Gravimetric Analysis ◽  
Lubricant Additives ◽  
Aliphatic Acid ◽  
Gravimetric Analysis ◽  
Edge Structure ◽  
Content Type ◽  
X Ray ◽  
Grafting Ratio ◽  
Surface Modified ◽  
X Ray Absorption

Purpose – The aim of this paper is to study the tribological performance and self-repairing performance of surface-modified nanoscale serpentine powders as lubricant additives in the mineral base oil (5-CST). Design/methodology/approach – Fourier transform infrared spectroscopy spectra and thermo-gravimetric analysis of both modified and unmodified serpentine were performed to analyse their grafting ratio and suspension after modified using a long-chain naphthene aliphatic acid. The tribological properties of surface-modified serpentine as lubricant additives in 5-CST were evaluated and the worn surfaces were investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). Findings – The results show that the serpentine particles have high grafting ratio, improving the dispersity in 5-CST. When the serpentine concentration of 1.00 weight per cent is used as additives in 5-CST, friction coefficient reduces by 14.80 per cent under 294 N and wear scar diameter (WSD) decreases by 11.82 per cent. The results of X-ray absorption near edge structure and XANES show that the adsorption and tribochemical reactions occur to form self-repairing lubrication films. Originality/value – The paper illustrates a tribofilm form on the rubbed surface, which is responsible for the decrease in friction and wear, mainly containing iron oxides, silicon oxides, magnesium oxides and organic compounds. The results are useful for further applications in advanced environmental friendly lubricating oils and additives.

Preparation and performance evaluation of mPAO8 using olefin from coal as raw material

2017 ◽  
Vol 69 (5) ◽  
pp. 678-682 ◽  
Author(s):  
Yuefeng Ma ◽  
Jian Xu ◽  
Xiangqiong Zeng ◽  
Haizhen Jiang ◽  
Jiusheng Li
Keyword(s):  
Thermal Stability ◽  
Oxidative Stability ◽  
Thermo Gravimetric Analysis ◽  
Viscosity Index ◽  
Oxidation Stability ◽  
Molecular Structures ◽  
Resonance Spectroscopy ◽  
Gravimetric Analysis ◽  
Content Type ◽  
Base Oil

Purpose The purpose of this paper is to prepare metallocene polyalphaolefin 8 (mPAO8) by the oligomerization of olefin from coal with metallocene catalyst system and compare it with commercially available polyalphaolefin 8 (PAO8) from Chevron. Design/methodology/approach Molecular structures, component and mass were determined by nuclear magnetic resonance spectroscopy, gas chromatography and gel permeation chromatography, respectively. The physico-chemical properties, including Noack volatility, viscosity index and elemental analyses, were studied. The oxidative stability was evaluated by pressurized differential scanning calorimetry, whereas the thermal stability was studied by thermo-gravimetric analysis. Findings The produced mPAO8 consisted of a large part of tetramer, pentamer and a small part of trimer and hexamer. Additive T501 significantly improved the oxidation stability of PAO8 from Chevron and the synthesized mPAO8. Both samples had similar properties, such as oxidative stability, additive response, pour point and Noack volatility loss. But mPAO8 possessed a higher thermal stability, better viscosity index and flash point than PAO8. Therefore, the mPAO8 prepared by the oligomerization of olefin from coal could be used as base oil for lubricant development. Originality/value The mPAO8 base oil was successfully prepared by successive carbon numbers and shows similar properties with commercially available PAO8 products from Chevron. The findings can cover the shortage of the synthesis lubricants market in China.

Effect of temperature on stress–strain behaviour of pre-damaged confined concrete

2019 ◽  
Vol 11 (1) ◽  
pp. 67-99
Author(s):  
Virendra Kumar
Keyword(s):  
Elevated Temperature ◽  
Axial Compression ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
Confined Concrete ◽  
Experimental Program ◽  
Test Results ◽  
Content Type ◽  
Confinement Reinforcement ◽  
Practical Implications

Purpose This paper aims to study the residual test results under uni-axial compression of tie confined pre-damaged normal strength concrete short columns subjected to elevated temperatures. Design/methodology/approach The test variables included temperature of exposure, spacing of transverse confining reinforcement and pre-damage level. An experimental program was designed and carried out involving testing of hoop confined concrete cylindrical specimens exposed to elevated temperatures ranging from room temperature to 900 °C. Findings The test results indicate that the residual strength, strain corresponding to the peak stress and the post-peak strains of confined concrete are not affected significantly up to an exposure temperature of 300 °C. However, the peak confined stress falls and the corresponding strain increase considerably in the temperature range of 600 to 900 °C. It is shown that an increase in the degree of confinement reinforcement results in an increased residual strength and deformability of pre-damaged confined concrete. Research limitations/implications It is applicable in finding the residual strength and strain of the pre-damaged confined concrete in uni-axial compression after exposure to elevated temperature. Practical implications The practical implications is that the test result is applicable in finding the residual strengths of pre-damaged confined concrete under uni-axial compression after exposure to elevated temperature. Social implications The main aim of the present investigation is to provide experimental data on the residual behaviour of pre-damaged confined concrete subjected to high temperatures. Originality/value The results of this study may be useful for developing the guidelines for designing the confinement reinforcement of reinforced concrete columns against the combined actions of earthquake and fire, as well as for designing the retrofitting schemes after these sequential disasters.

Shape memory polymer composite coatings with enhanced mechanical and antimicrobial properties

2018 ◽  
Vol 47 (1) ◽  
pp. 63-71 ◽  
Author(s):  
Xin Wang ◽  
Xiaoling Xu ◽  
Zuowan Zhou ◽  
Jihua Gou
Keyword(s):  
Wear Resistance ◽  
Shape Memory ◽  
Spray Deposition ◽  
Low Cost ◽  
Composite Coatings ◽  
Shape Memory Polymer ◽  
Antimicrobial Property ◽  
Thermo Gravimetric Analysis ◽  
Gravimetric Analysis ◽  
Content Type

Purpose This paper aims to exploit shape memory polymer (SMP) composite as multifunctional coatings for protecting substrates from surface wear and bacterial. The efficiency of added nano or micro-sized particles in enhancing the properties of SMP was investigated. This study also attempts to use a low-cost and effective spraying approach to fabricate the coatings. The coatings are expected to have good conformability with the substrate and deliver multi-functional performance, such as wrinkle free, wear resistance, thermal stability and antimicrobial property. Design/methodology/approach High-performance SMP composite coatings or thin films were fabricated by a home-made continuous spray-deposition system. The morphologies of the coatings were studied using the scanning electron microscope and the transmission electron microscope. The abrasion properties were evaluated by Taber Abraser test, and thermo-gravimetric analysis was carried out to investigate the thermal properties of prepared composites. The antimicrobial property was determined by the inhibition zone method using E. coli. The thermally responsive shape memory effect of the resulting composites was also characterized. Findings The morphology analysis indicated that the nanoclay was distributed on the surface of the coating which resulted in a significant improvement of the wear property. The wear resistance of the coatings with nanoclay was improved as much as 40 per cent compared with that of the control sample. The thermo-gravimetric analysis revealed that the weight loss rate of composites with nanoclay was dropped over 40 per cent. The SMP coating with zinc oxide (ZnO) showed excellent antimicrobial effect. The shape recovery effect of SMP/nanoclay and SMP/ZnO composites can be triggered by external heating and the composites can reach a full shape recovery within 60 s. Research limitations/implications This study proposed a continuous spray-deposition fabrication of SMP composite coatings, which provides a new avenue to prepare novel multi-functional coatings with low cost. Originality/value Most studies have emphasized on the sole property of SMP composites. Herein, a novel SMP composite coating which could deliver multi-functionality such as wrinkle free, wear resistance, thermal stability and antimicrobial property was proposed.

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