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Effect of fiber hybridization on energy absorption and synergy in concrete

Ahmadreza RAMEZANI, Mohammad Reza ESFAHANI

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1338-1349 doi: 10.1007/s17009-019-0558-2

摘要: In the present study, steel and polypropylene (PP) fibers have been utilized with the intent of obtaining hybrid fiber-reinforced concrete (HFRC) with desirable mechanical properties. An attempt has been made to scrutinize the properties of HFRC with the main concentration being on energy absorption characteristics of concrete and the efficacy of fiber hybridization in producing synergy. Accordingly, a total of 180 specimens, representing 20 different mixtures have been cast and evaluated through compressive, split tensile, and flexural tests. The relevant flexural toughness of the specimens was calculated using ASTM C1018, ASTM C1609, JSCE, and PCS methods, and the effectiveness of these methods was evaluated based on the experimental results. It was observed that steel fibers are more effective in the improvement of flexural toughness in the presence of PP fibers. Furthermore, synergy associated with the combination of fibers at different stages of deflection of the beam specimens was observed and analyzed.

关键词: hybrid fiber-reinforced concrete     synergy     toughness     steel fibers     polypropylene fibers    

Optimizing the compressive strength of concrete containing micro-silica, nano-silica, and polypropylenefibers using extreme vertices mixture design

Fatemeh ZAHIRI, Hamid ESKANDARI-NADDAF

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 821-830 doi: 10.1007/s11709-019-0518-6

摘要: Many studies have evaluated the effects of additives such as nano-silica (NS), micro-silica (MS) and polymer fibers on optimizing the mechanical properties of concrete, such as compressive strength. Nowadays, with progress in cement industry provides, it has become possible to produce cement type I with strength classes of 32.5, 42.5, and 52.5 MPa. On the one hand, the microstructure of cement has changed, and modified by NS, MS, and polymers; therefore it is very important to determine the optimal percentage of each additives for those CSCs. In this study, 12 mix designs containing different percentages of MS, NS, and polymer fibers in three cement strength classes(CSCs) (32.5, 42.5, and 52.5 MPa) were designed and constructed based on the mixture method. Results indicated the sensitivity of each CSCs can be different on the NS or MS in compressive strength of concrete. Consequently, strength classes have a significant effect on the amount of MS and NS in mix design of concrete. While, polymer fibers don’t have significant effect in compressive strength considering CSCs.

关键词: mixture method     compressive strength     nano-silica     micro-silica     polypropylene fibers    

Dyeing fine denier polypropylene fibers with phenylazo- β -naphthol-containing sulfonamide disperse

Zhihua CUI, Weiguo CHEN, Jinzong YANG, Shufen ZHANG,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 328-335 doi: 10.1007/s11705-009-0216-3

摘要: A series of phenylazo--naphthol-containing sulfonamide disperse dyes were prepared from C.I. Acid Orange 7 by successive reactions of chlorination and amination, and their chemical structures were characterized by FTIR, H NMR, and mass spectrometry. The dyes were applied to coloring of knitted fabrics from fine denier polypropylene fibers by exhaust dyeing and their optimal dyeing conditions, such as dyebath pH, dyeing temperature, dyeing time, and dye concentration were investigated in detail. Then, dye exhaustion, color strength, and color fastnesses of the dyes on the fibers were assessed and summarized. In view of dye exhaustion and color strength of the sulfonamide dyes on fine denier PP fabrics, 90°C was selected as the best dyeing temperature at dye concentration below or equal to 3.0% owf. For achieving higher color strength, 130°C was the better choice when the dye concentration was above 3.0% owf. The sulfonamide dyes, especially secondary sulfonamide dyes, exhibited superior dye exhaustion and color fastnesses to washing, sublimation, and rubbing on fine denier PP fabrics in comparison to C.I. Solvent Yellow 14 bearing the same chromophore but without sulfonamide group.

关键词: polypropylene     FTIR     secondary sulfonamide     Orange     concentration    

The effect of carbon nanotubes and polypropylene fibers on bond of reinforcing bars in strain resilient

Souzana P. TASTANI,Maria S. KONSTA-GDOUTOS,Stavroula J. PANTAZOPOULOU,Victor BALOPOULOS

《结构与土木工程前沿(英文)》 2016年 第10卷 第2期   页码 214-223 doi: 10.1007/s11709-016-0332-3

摘要: Stress transfer between reinforcing bars and concrete is engaged through rib translation relative to concrete, and comprises longitudinal bond stresses and radial pressure. The radial pressure is equilibrated by hoop tension undertaken by the concrete cover. Owing to concrete’s poor tensile properties in terms of strength and deformability, the equilibrium is instantly released upon radial cracking of the cover along the anchorage with commensurate abrupt loss of the bond strength. Any improvement of the matrix tensile properties is expected to favorably affect bond in terms of strength, resilience to pullout slip, residual resistance and controlled slippage.The aim of this paper is to investigate the local bond of steel bars developed in adverse tensile stress conditions in the concrete cover. In the tests, the matrix comprises a novel, strain resilient cementitious composite (SRCC) reinforced with polypropylene fibers (PP) with the synergistic action of carbon nano-tubes (CNT). Local bond is developed over a short anchorage length occurring in the constant moment region of a four-point bending short beam. Parameters of investigation were the material structure (comprising a basic control mix, reinforced with CNTs and/or PP fibers) and the age of testing. Accompanying tests used to characterize the cementitious material were also conducted. The test results illustrate that all the benefits gained due to the synergy between PP fibers and CNTs in the matrix, namely the maintenance of the multi-cracking effect with time, the increased strength and deformability as well as the highly increased material toughness, were imparted in the recorded bond response. The local bond response curves thus obtained were marked by a resilient appearance exhibiting sustained strength up to large levels of controlled bar-slip; the elasto-plastic bond response envelope was a result of the confining synergistic effect of CNTs and the PP fibers, and it occurred even without bar yielding.

关键词: carbon nanotubes     strain resilient cementitious composite     polypropylene fibers     tensile bending     bond    

Investigation on multiple-melting behavior of nano-CaCO3/polypropylene composites

LIN Zhidan, ZENG Chunlian, MAI Kancheng

《化学科学与工程前沿(英文)》 2007年 第1卷 第1期   页码 81-86 doi: 10.1007/s11705-007-0017-5

摘要: The multiple melting-peak behavior of polypropylene (PP) in nano-CaCO/PP composites and modified nano-CaCO/PP composites were investigated under the condition of isothermal crystallization and nonisothermal crystallization. The result indicated that the addition of nano-CaCO markedly increased the crystallization temperatures of PP and induced the formation of the β-crystal of PP. The crystallization temperatures of nano-CaCO/PP composites modified by reactive monomers were further increased, but the melting-peak intensity of the β-crystal of PP was not greatly influenced. While in the presence of dicumyl peroxide, nano-CaCO/PP composites modified by reactive monomers led to the significant increase in the melting-peak intensity of the β-crystal of PP. The double melting-peak of PP was observed, which was attributed to the formation of two kinds of different crystallization forms of α-crystal or β-crystal during the crystallization of PP. With the increase of crystallization temperatures, the double melting-peak moved toward the high-temperature side. The intensity of high-temperature melting peak was higher than that of low-temperature melting peak in nano-CaCO/PP composites. While in modified nano-CaCO/PP composites crystallized at higher temperature, the intensity of high-temperature melting peak was lower than that of low-temperature melting peak. The isothermal crystallization time had little effect on the melting temperatures.

关键词: polypropylene     nano-CaCO/PP     presence     melting-peak behavior     low-temperature    

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

Mohammed FARUQI, Mohammed Sheroz KHAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第1期   页码 81-91 doi: 10.1007/s11709-018-0468-4

摘要: Fiber reinforced polymer(FRP) have unique advantages like high strength to weight ratio, excellent corrosion resistance, improving deformability and cost effectiveness. These advantages have gained wide acceptance in civil engineering applications. FRP tendons for prestressing applications are emerging as one of the most promising technologies in the civil engineering industry. However, the behavior of such members under the influence of elevated temperatures is still unknown. The knowledge and application of this could lead to a cost effective and practical considerations in fire safety design. Therefore, this study examines the deflection behavior of the carbon fiber reinforced polymer(CFRP) prestressed concrete beam at elevated temperatures. In this article, an analytical model is developed which integrates the temperature dependent changes of effective modulus of FRP in predicting the deflection behavior of CFRP prestressed concrete beams within the range of practical temperatures. This model is compared with a finite element mode (FEM) of a simply supported concrete beam prestressed with CFRP subjected to practical elevated temperatures. In addition, comparison is also made with an indirect reference to the real behavior of the material. The results of the model correlated reasonably with the finite element model and the real behavior. Finally, a practical application is provided.

关键词: FRP     CFRP     concrete     elevated temperatures     deflections     prestress    

The damage evolution behavior of polypropylene fiber reinforced concrete subjected to sulfate attack

Ninghui LIANG; Jinwang MAO; Ru YAN; Xinrong LIU; Xiaohan ZHOU

《结构与土木工程前沿(英文)》 2022年 第16卷 第3期   页码 316-328 doi: 10.1007/s11709-022-0810-8

摘要: To study the damage evolution behavior of polypropylene fiber reinforced concrete (PFRC) subjected to sulfate attack, a uniaxial compression test was carried out based on acoustic emission (AE). The effect of sulfate attack relative to time and fiber hybridization were analyzed and the compression damage factor was calculated using a mathematical model. The changes to AE ringing counts during the compression could be divided into compaction, elastic, and AE signal hyperactivity stages. In the initial stage of sulfate attack, the concrete micropores and microcracks were compacted gradually under external load and a corrosion products filling effect, and this corresponded with detection of few AE signals and with concrete compression strength enhancement. With increasing sulfate attack time, AE activity decreased. The cumulative AE ringing counts of PFRC at all corrosion ages were much higher than those for plain concrete. PFRC could still produce AE signals after peak load due to drawing effect of polypropylene fiber. After 150 d of sulfate attack, the cumulative AE ringing counts of plain concrete went down by about an order of magnitude, while that for PFRC remained at a high level. The initial damage factor of hybrid PFRC was −0.042 and −0.056 respectively after 150 d of corrosion, indicating that the advantage of hybrid polypropylene fiber was more obvious than plain concrete and single-doped PFRC. Based on a deterioration equation, the corrosion resistance coefficient of hybrid PFRC would be less than 0.75 after 42 drying−wetting sulfate attack cycles, which was 40% longer than that of plain concrete.

关键词: polypropylene fiber reinforced concrete     sulfate attack     damage evolution behavior     acoustic emission     damage factor    

Recent developments in the application of oil palm fibers in cement composites

Emmanuel Owoichoechi MOMOH, Adelaja Israel OSOFERO

《结构与土木工程前沿(英文)》 2020年 第14卷 第1期   页码 94-108 doi: 10.1007/s11709-019-0576-9

摘要: Fibers obtained from different parts of the oil palm tree (Elaeis guineensis) have been under investigation for possible use in construction. Studies have been carried out investigating the engineering properties and possible applications of these fibers. However, the experimental methods employed and the values of mechanical and physical properties recorded by various authors are inconsistent. It has therefore become necessary to organize information which would be useful in the design of oil palm fiber cement composites and help researchers and engineers make informed decisions in further research and application. This review provides information about fibers from different parts of the oil palm, their properties, enhancement techniques, current and potential application in cement composites.

关键词: broom     cement composite     concrete     oil palm fiber     Natural fiber-concrete     sustainability    

environmental temperature and relative humidity on photocatalytic oxidation of toluene on activated carbon fibers

GUO Ting, BAI Zhipeng, WU Can, ZHU Tan

《环境科学与工程前沿(英文)》 2008年 第2卷 第2期   页码 224-229 doi: 10.1007/s11783-008-0039-3

摘要: TiO supported on active carbon fiber (TiO/ACF), an absorbable photocatalyst, is a new kind of material applied in air purification. In this paper, the influence of environmental temperature (T) and relative humidity (RH) on the gas-solid adsorption of toluene and the photocatalytic oxidation (PCO) efficiency of adsorbed toluene on TiO/ACF were studied, and then, the purification capability of TiO/ACF was estimated. PCO results showed that although the PCO efficiency increased under high RH and T levels, the amount of adsorption of toluene decreased. Moreover, quantitative analysis results of intermediates indicated that more environmental risk emerged when PCO of toluene was carried out at higher environmental T and RH levels because more toxic intermediates would be accumulated on the TiO/ACF. So, it is significant to control the environmental T and RH conditions in the application of the PCO technique. T = 25°C and RH = 30% is the optimal condition for purifying toluene in our experimental system.

关键词: application     gas-solid adsorption     technique     TiO/ACF     experimental    

聚丙烯技术进展

袁晴棠

《中国工程科学》 2001年 第3卷 第9期   页码 29-36

摘要:

简要回顾了聚丙烯技术近半个世纪的发展历程,概述了国内外聚丙烯技术的主要进展,对今后我国聚丙烯技术发展方向进行了初步探讨。

关键词: 聚丙烯     技术进展     发展方向    

Phenolic rigid organic filler/isotactic polypropylene composites. III. Impact resistance property

Heming LIN, Dongming QI, Jian HAN, Zhiqi CAI, Minghua WU

《化学科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 176-181 doi: 10.1007/s11705-009-0203-8

摘要: A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the impact resistance property of PP/KT specimens (with similar interparticles distance, 1.8 μm) was studied by notched izod impact tests. It was found that the brittle-ductile transition (BDT) of the PP/KT microcomposites took place at the filler content of about 4%, and the impact strength attains the maximum at 5% (with filler particles size of 1.5 μm), which is about 2.5 times that of unfilled iPP specimens. The impact fracture morphology was investigated by scanning electron microscopy (SEM). For the PP/KT specimens and the high-density polyethylene/KT (HDPE/KT) specimens in ductile fracture mode, many microfibers could be found on the whole impact fracture surface. It was the filler particles that induced the plastic deformation of interparticles ligament and hence improved the capability of iPP matrix on absorbing impact energy dramatically. The determinants on the BDT were further discussed on the basis of stress concentration and debonding resistance. It can be concluded that aside from the interparticle distance, the filler particles size also plays an important role in semicrystalline polymer toughening.

关键词: rigid organic filler     polypropylene     impact resistance    

Dispersion of a novel phenolic rigid organic filler in isotactic polypropylene matrix by solution-mixing

Dongming QI, Xiaoli ZHAO, Zhijie CHEN, Peng HUANG, Jun CAO

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 395-402 doi: 10.1007/s11705-012-1269-2

摘要: A novel phenolic rigid organic filler (named KD) with a high melting point was dispersed in an isotactic polypropylene (iPP) matrix by solution-mixing and/or melt-mixing. A series of KD/iPP blends was prepared with or without addition of maleic anhydride-grafted polypropylene (MAPP) as a compatibilizer. Influences of MAPP and mixing methods on the filler dispersion were studied using polaried optical microscope (POM), scanning electron microscope (SEM) and tensile test. The filler particles are always inclined to form large irregular aggregates in the iPP matrix due to their significant differences in polarity and solubility in solvent. However, an iPP/MAPP/KD (PMK) blend containing filler particles with a quasi-spherical shape (~97.8 nm in diameter) and narrow particle size distribution (polydispersity index= 1.076) was successfully prepared by incorporating MAPP to reduce the interfacial tension and surface free energy between the dispersion phase and the continuous phase, and adopting a spray-drying method after solution-mixing to suppress the increase of the size of the dispersed phase during the removal of solvent.

关键词: dispersion     rigid organic filler     isotactic polypropylene     mixing    

Phenolic rigid organic filler/isotactic polypropylene composites. II. Tensile properties

QI Dongming, SHAO Jianzhong, WU Minghua, NITTA Kohhei

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 396-401 doi: 10.1007/s11705-008-0077-1

摘要: A novel phenolic rigid organic filler (KT) was used to modify isotactic polypropylene (iPP). The influence of KT particles on the tensile properties of PP/KT microcomposites was studied by uniaxial tensile test and the morphological structures of the stretched specimens were observed by scanning electron microscopy (SEM) and polarized optical microscopy (POM). We found that the Young’s modulus of PP/KT specimens increased with filler content, while the yield and break of the specimens are related to the filler particles size. The yield stress, the breaking stress and the ultimate elongation of PP/KT specimens were close to those of unfilled iPP specimens when the maximal filler particles size is less than a critical value, which is 7 ?m at a crosshead speed of 10 mm/min and 3 ?m at 200 mm/min, close to that of glass bead but far more than those of other rigid inorganic filler particles. The interfacial interaction was further estimated from yield stress, indicating that KT particles have a moderate interfacial interaction with iPP matrix. Thus, the incorporation of small KT particles can reinforce iPP matrix and simultaneously cause few detrimental effects on the other excellent tensile properties of iPP matrix, due to their organic nature, higher specific area, solid true-spherical shape and the homogenous dispersion of the ROF particles in microcomposites.

关键词: maximal     uniaxial tensile     unfilled     excellent tensile     influence    

Fabrication of recyclable Fe chelated aminated polypropylene fiber for efficient clean-up of phosphate

《化学科学与工程前沿(英文)》 2023年 第17卷 第7期   页码 840-852 doi: 10.1007/s11705-022-2253-0

摘要: Herein, a Fe3+-loaded aminated polypropylene fiber has been reported as an efficient phosphate adsorbent. The remarkable phosphate removal ability of the fiber is due to Fe3+ immobilization, and it demonstrates a maximum adsorption capacity of 33.94 mg·P·g–1. Adsorption experiments showed that the fiber is applicable over a wide pH range from 2 to 9. Furthermore, the adsorption kinetics and isotherm data were consistent with the pseudo-second-order and Langmuir adsorption models, respectively. The adsorption equilibrium of the fiber for phosphate was reached within 60 min, indicating an efficient monolayer chemisorption process. Moreover, the adsorbent maintained prominent phosphate removal in the presence of competitive ions such as NO3 and Cl, exhibiting high selectivity. More importantly, the fiber demonstrated excellent reusability (5 times) and low adsorption limit below 0.02 mg·P·g–1. In addition, the phosphate removal efficiency of the fiber can exceed 99% under continuous flow conditions. The adsorption mechanism was studied by X-ray photoelectron spectroscopy, showing that the adsorption of phosphate on the fiber mainly depended on the chemical adsorption of the modified Fe3+. Overall, this study proves that the fiber possesses many advantages for phosphate removal, including high adsorption efficiency, lower treatment limit, good recyclability, and environmental friendliness.

关键词: phosphate adsorption     aminated polypropylene fiber     Fe3+     ligand exchange     reusability    

推进我国产业用化纤材料的发展

季国标

《中国工程科学》 2003年 第5卷 第7期   页码 24-28

摘要:

回顾了10多年来产业用化纤材料的发展,提出现正处在持续增长期。参考世界发展情况,吸取其中有益的经验。结合我国实际,陈述了大类应用领域的前景以及在宏观管理上需要加强的有关问题。

关键词: 中国     产业用化纤材料     发展    

标题 作者 时间 类型 操作

Effect of fiber hybridization on energy absorption and synergy in concrete

Ahmadreza RAMEZANI, Mohammad Reza ESFAHANI

期刊论文

Optimizing the compressive strength of concrete containing micro-silica, nano-silica, and polypropylenefibers using extreme vertices mixture design

Fatemeh ZAHIRI, Hamid ESKANDARI-NADDAF

期刊论文

Dyeing fine denier polypropylene fibers with phenylazo- β -naphthol-containing sulfonamide disperse

Zhihua CUI, Weiguo CHEN, Jinzong YANG, Shufen ZHANG,

期刊论文

The effect of carbon nanotubes and polypropylene fibers on bond of reinforcing bars in strain resilient

Souzana P. TASTANI,Maria S. KONSTA-GDOUTOS,Stavroula J. PANTAZOPOULOU,Victor BALOPOULOS

期刊论文

Investigation on multiple-melting behavior of nano-CaCO3/polypropylene composites

LIN Zhidan, ZENG Chunlian, MAI Kancheng

期刊论文

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

Mohammed FARUQI, Mohammed Sheroz KHAN

期刊论文

The damage evolution behavior of polypropylene fiber reinforced concrete subjected to sulfate attack

Ninghui LIANG; Jinwang MAO; Ru YAN; Xinrong LIU; Xiaohan ZHOU

期刊论文

Recent developments in the application of oil palm fibers in cement composites

Emmanuel Owoichoechi MOMOH, Adelaja Israel OSOFERO

期刊论文

environmental temperature and relative humidity on photocatalytic oxidation of toluene on activated carbon fibers

GUO Ting, BAI Zhipeng, WU Can, ZHU Tan

期刊论文

聚丙烯技术进展

袁晴棠

期刊论文

Phenolic rigid organic filler/isotactic polypropylene composites. III. Impact resistance property

Heming LIN, Dongming QI, Jian HAN, Zhiqi CAI, Minghua WU

期刊论文

Dispersion of a novel phenolic rigid organic filler in isotactic polypropylene matrix by solution-mixing

Dongming QI, Xiaoli ZHAO, Zhijie CHEN, Peng HUANG, Jun CAO

期刊论文

Phenolic rigid organic filler/isotactic polypropylene composites. II. Tensile properties

QI Dongming, SHAO Jianzhong, WU Minghua, NITTA Kohhei

期刊论文

Fabrication of recyclable Fe chelated aminated polypropylene fiber for efficient clean-up of phosphate

期刊论文

推进我国产业用化纤材料的发展

季国标

期刊论文