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Identification of parameter to assess cracking resistance of asphalt mixtures subjected to aging and moisture conditioning

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第2期9卷 293-304页

作者： Bhaskar Pratim Das Anjan Kumar Siddagangaiah Department of Civil Engineering Indian Institute of Technology GuwahatiGuiuahati 781039India

This study comprehensively evaluated different parameters based on tensile strength testing to assess the cracking resistance of asphalt mixtures subjected to aging and moisture conditioning.For this purpose,two sources of aggregates were selected to produce hot and warm mix asphalt mixtures.Asphalt mixtures were subjected to short term and long term aging,three levels of moisture conditioning(freeze thaw cycles),and tested at two temperatures(15℃and 25℃).The load-displacement data was used to determine the fracture work density,fracture energy,toughness index,cracking resistance index,cracking tolerance index,and rate dependent cracking index.It was noticed that moisture conditioning increased the variability of the different parameters.The cracking tolerance index and rate dependent cracking index parameter had a much higher coefficient of variation(Co V)with a maximum value close to 50%.Indirect tensile strength,fracture energy,and fracture work density appropriately captured the effect of moisture on cracking resistance of mixtures.The cracking resistance index,cracking tolerance index,and rate dependent cracking index increased with an increase in the moisture conditioning level.The Statistical analysis showed that tensile strength,fracture work density,and fracture energy were significantly influenced by different aging and moisture conditions evaluated.Fracture energy showed better association with fatigue life of asphalt mixtures subjected to three freeze-thaw cycles compared to tensile strength.Further,the fatigue life prediction models showed that both indirect tensile strength and fracture energy significantly influence the fatigue life of asphalt mixtures subjected to aging and moisture conditioning.

关键词： cracking resistance Aging Moisture Warm mix additive Fatigue life

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Elasto-Plastic Test of Q235 Steel Bending Beam With cracking resistance

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Journal of Iron and Steel Research(International) 2013年第11期20卷 57-66页

作者： WANG Li-min FENG Ying CHEN Fan-xiu WANG Hai-ying WANG Dong-xu Science School Qingdao Technological University Institute of Mechanics Chinese Academy of Sciences

More than 30 bending beams with rectangular cross-section and different thicknesses and heights were pre- pared from Q295 steel. The specimen dimensions were about 240 mm （length） × 60 mm （height） ×70 mm （thick ness）. Flaws were cut along its middle line with a wire cutter, with lengths ranging from 6 to 35 mm. Each specimen was tested with three-point bend loading, and a process curve was obtained between load and the displacement of the loading point, in order to analyze the fracture process when opening the crack. A deformation near the prefabricated crack was observed in the testing period, and the variation of the fracture characteristic parameters was analyzed for different sizes. For a comprehensive understanding of carbon steel fracture resistance behavior, its elasticity and plas- ticity were established by determining its Young＇s modulus and Poisson＇s ratio with an optical strain gauge. This gauge was also used for the loading process test. It was found that the fracture toughness varied with the dimensions, and the toughness of the elastic limit loading was almost constant. Using the relationship of crack resistance stress intensity factor and fracture criterion, the bearing capacity of the material structure could be estimated, which shows a good agreement with the experimental test data.

关键词： elasto-plastic property fracture toughness elastic limit loading bearing capacity cracking resistance Q235 steel bending beam

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Effect of RE on cracking resistance and Microstructure of Coatings Formed by Plasma Jet Surface Metallurgy

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Journal of Rare Earths 2005年第S1期23卷 383-386页

作者：陈颢李惠琪孙玉宗 School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China School of Materials Science and Engineering Shandong University of Science and Technology Qingdao 266510 China School of Materials Science and Engineering Shandong University of Science and Technology Qingdao 266510 China

Metallurgical coatings of iron-based alloy with RE oxide were prepared on low-carbon steel using a home-made DC-plasma jet surface metallurgy equipment. Scanning electron microscope (SEM), energy dispersive X-ray (EDX) microanalysis and X-ray diffraction analysis (XRD) were employed to observe the microstructure and analyze the chemical compositions of coatings. And the cracking susceptibility of coatings was studied in terms of RE addition. Experimental results show that addition of RE oxide (La_2O_3 and CeO_2) can refine and purify the microstructure, and can reduce the cracking susceptibility of coatings.

关键词： plasma jet surface metallurgy cracking resistance microstructure rare earths

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Evaluation of cracking resistance of Copper-Bearing Age Hardening Steel Weldment

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Journal of Iron and Steel Research(International) 2007年第3期14卷 56-62页

作者： CHAI Feng YANG Cai-fu SU Hang ZHANG Yong-quan XU Zhou School of Materials Science and Engineering Shanghai Jiaotong University Shanghai 200030 China Institute of Structural Materials Central Iron and Steel Research Institute Beijing 100081 China

The weldability of a low-carbon copper-bearing age hardening steel was evaluated using cracking suscepti- bility calculation, HAZ maximum hardness measurement, and Y-groove cracking evaluation test. The results show that the hardenability characteristics and cold cracking susceptibility of the steel are very low. The results also indicate that a crack-free weldment can be obtained during the welding of this type of steel even at an ambient temperature as low as -5 ℃ as well as in an absolute humidity lower than 4 000 Pa without any preheat treatment. A slight preheat treatment can prevent the joint from cracking when welding is carried out at lower ambient temperature or higher absolute humidity.

关键词： copper-bearing age hardening steel weldability cracking resistance Y-groove cracking test

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Effect of RE Oxide on cracking resistance of Hardfacing Metal

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Journal of Rare Earths 1998年第4期16卷 56-60页

作者：杨庆祥任学军廖波姚枚万鑫 College of Materials Engineering Yanshan University Qinhuangdao 066004 China College of Materials Engineering Harbin Institute of Technology Harbin 150001 China

The crack morphologies of hardfacing metal were observed by means of optical microscope and scanning electron microscope. Meanwhile, the cracking resistances of hardfacing metal were investigated. The results show that the solidification cracking and quench hardened cracking are the main forms of cracking in hardfacing metal. The cracking resistance of hardfacing metal can be improved by adding rare earth oxide in the coat of electrode.

关键词： Rare earths Hardfacing metal cracking resistance

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Effect of Oils on SBS Modified Asphalt:Rheological Characteristics and Oxidation Aging

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Journal of Renewable Materials 2023年第3期11卷 1339-1351页

作者： Jing Xu Yuquan Yao Kai Zhang Jiangang Yang Jie Gao Jian Zhou Jiangxi Transportation Institute Co. Ltd.Nanchang330200China School of Civil Engineering and Architecture East China Jiaotong UniversityNanchang330013China School of Highway Chang’an UniversityXi’an710064China

This study focuses on the effect of oils on rheology and oxidation aging of Styrene-Butadiene-Styrene modified asphalt(SBSMA)in the long term,after reducing one low-temperature Performance Grade(PG)of SBSMA by incorporating oils.Two oils,including corn-based bio-oil and re-refined engine oil bottom(REOB),were selected to enhance the low-temperature performance of SBSMA.All samples were subjected to Rolling Thin Film Oven(RTFO)aging and 20-h as well as 40-h Pressure Aging Vessel(PAV20 and PAV40)aging,prior to multiple stress creep recovery(MSCR),frequency sweep and Flourier transform infrared spectroscopy(FTIR)scanning.A good high-temperature performance of oil/SBS modified asphalt blends was reflected in MSCR and PG results,meanwhile non-recoverable creep compliance(Jnr)and recovery(R)were found to share a highly correlated relationship during aging progress.In addition,Glover–Rowe(G–R)parameter and phase angle master curves suggest that the improvement of cracking property mainly came from the softening effect of oils.Adding oils into SBSMA was observed to increase oxidation kinetics,but the blends with oils still exhibited better anti-oxidation aging than the base binder,mainly due to the SBS addition.Bio-oil exhibited an effect of relieving age hardening susceptibility of SBSMA.

关键词： Oil aging rheology oxidation kinetics cracking resistance

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Laboratory Evaluation of Fiber-Modified Asphalt Mixtures Incorporating Steel Slag Aggregates

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Computers, Materials & Continua 2022年第3期70卷 5967-5990页

作者： Adham Mohammed Alnadish Mohamad Yusri Aman Herda Yati Binti Katman Mohd Rasdan Ibrahim Department of Civil Engineering and Built Environment Universiti Tun Hussein Onn MalaysiaParit Raja86400Malaysia Department of Civil Engineering Universiti Tenaga NasionalKajang43000Malaysia Department of Civil Engineering Universiti MalayaKuala Lumpur50603Malaysia

Vigorous and continued efforts by researchers and engineers have contributed towards maintaining environmental sustainability through the utilization of waste materials in civil engineering applications as an alternative to natural sources.In this study,granite aggregates in asphaltic mixes were replaced by electric arc furnace(EAF)steel slag aggregates with different proportions to identify the best combination in terms of superior performance.Asphalt mixtures showing the best performance were further reinforced with polyvinyl alcohol(PVA),acrylic,and polyester fibers at the dosages of 0.05%,0.15%,and 0.3%by weight of the aggregates.The performance tests of this study were resilient modulus,moisture susceptibility,and indirect tensile fatigue cracking test.The findings of this study revealed that the asphalt mixtures containing coarse steel slag aggregate exhibited the best performance in comparison with the other substitutions.Moreover,the reinforced asphalt mixtures with synthetic fibers at the content of 0.05%exhibited an almost comparable performance to the unreinforced asphalt mixtures.Modifying the asphalt mixtures with PVA,acrylic,and polyester fibers at the proportion of 0.15%have improved the fatigue cracking resistance by 41.13%,29.87%,and 18.97%,respectively.Also,the fiber-modified asphalt mixtures with PVA,acrylic,and polyester have enhanced the fatigue cracking resistance by about 57%,44%,and 39%,respectively.The results of the resilient modulus demonstrated that as the fiber content increase,the resilient modulus of the reinforced asphalt mixtures decreases.Therefore,introducing synthetic fibers at the content of 0.3%has slightly decreased the resilient modulus in comparison with unreinforced mixtures.On the other hand,the results of the mechanisticempirical pavement design showed that the reinforced asphalt mixes with a high content of synthetic fibers have shown lower service life than the control mixes due to the low resilient modulus.On the contrary,based on the laboratory results,the asphalt m

关键词： Steel slag aggregate polyvinyl alcohol fiber acrylic fiber polyester fiber cracking resistance resilient modulus

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Biomechanical properties of ready-to-harvest rapeseed plants:Measurement and analysis

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Information Processing in Agriculture 2023年第3期10卷 391-399页

作者： Guangchao Zhan Wangyuan Zong Lina Ma Junyi Wei Wei Liu College of Engineering Huazhong Agricultural UniversityWuhan 430070PR China Key Laboratory of Agricultural Equipment in Middle-lower Reaches of the Yangtze River Ministry of Agriculture and Rural AffairsWuhan 430070PR China

A large loss occurs in the combine harvesting of rapeseeds due to the fragility of rapeseed pods,and all the more so with the vibration of the combine header and the collision between the header and plants.Seed loss is greatly affected by the biomechanical properties of ready-to-harvest rapeseed plants.To understand the mechanism of pod cracking and seed loss and to propose measures for alleviating them,it is needed to study the biomechanical properties of ready-to-harvest rapeseed plants.To this end,“Huayouza 62”,a widely planted rapeseed variety in central China,was selected to study the biomechanical properties,including pod-cracking resistance,main stem-shearing resistance and resonant frequencies,of whole plants.The results showed that the distribution of pod-cracking resistance forces was 1.333–6.100 N in the mature stage,and the pod width and thickness had a significant influence on the cracking resistance.The main influencing factor of the main stem-shearing resistance was the stem diameter.A thicker main stem resulted in a larger shearing resistance force but a smaller shear stress.The moisture contents of the main stems varied from 47.71%to 76.13%.However,the varying moisture contents did not show a significant impact on the shearing resistance.The resonant frequencies of whole rapeseed plants ready for harvest ranged from 6.5 Hz to 7.5 Hz,which was close to the excitation frequency of the cutter bar on the 4LL-1.5Y harvester.This study lays a foundation for improving the design and construction of harvesting devices for rapeseed plants to reduce seed loss.

关键词： Rapeseed pod cracking resistance Shearing resistance Resonant frequency Rapeseed harvesting

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Development and Validation of a Laboratory Aging Method for the Accelerated Simulation of Reclaimed Asphalt

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Journal of Wuhan University of Technology(Materials Science) 2010年第4期25卷 631-636页

作者： MOLLENHAUER K PIERARD N TUSAR M MOUILLET V GABET T Braunschweig Pavement Engineering Centre Belgium Road Research Centre Slovenian National Building and Civil Engineering Institute CETE Méditerranée Aix en Provence France Laboratoire de Ponts et Chaussées Nantes France

The paper presented first results elaborated during the European Research Project Re-road which aims at the development of techniques for increasing the recycling rates of reclaimed asphalt. During service life surface asphalt courses are subjected to aging due to oxidation effects which causes the hardening of the binder and thereby a change in the chemical, physical and mechanical properties of the material. Surface courses often contain highly modified binders as well as special additives for improving the performance characteristics. As these layers inhibit the shortest service lives compared to other road construction layers every year high amounts of reclaimed surface asphalt are available for recycling. The question is raised how the reclaimed asphalt consisting of high quality and costly material components can be recycled for optimal added value. To analyze the asphalt mix service life performance and its recyclability during mix design a laboratory method was developed to simulate the real in-situ aging. First the effects of site aging on the binder and asphalt characteristics were presented. Three laboratory aging methods were discussed which aimed the accelerated aging which meets similar property changes as site aging. At last the effects of two different laboratory aging methods on the same SMA mixture were compared.

关键词： asphalt recycling laboratory aging site aging long-term aging validation tests chemical characteristics cracking resistance

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cracking Mechanism of Medium-High Carbon Steel during Hardfacing and Effect of Electrode Composition

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材料导报 1998年第5期 71-71页

作者：杨庆祥燕山大学材料工程学院秦皇岛市 066004

In this paper,the temperature and stress fields during hardfacing and the crack mor-phology in welded specimens were studied by using a medium-high carbon steel 60CrMnMo, and a RE-doped electrode for cracking resistance has been developed.The temperature fields on the upper surface of simulated specimens during the hardfacing and the following colding were measured by a thermovision analyzer and the residual stress fields were determined by an X-ray stress analyzer. Both these fields have been simulated by usmg the FEM. The calculated re-sults of the temperature and the residual stress fields talhed with the measured ones quite well. The calcu-lations for establishing the influence of martensite transformation temperatures of the hardfacing metal on the stress distribution m simulated specimens show that,with their lowering,the peaks of tensile residual stress at dangerous positions reduce which is considered to be benefit to avoid the occurence of hardfacing cracks.It is shown that,by adding the RE-oxi

关键词： hardfaceing of medium-high carbon steel stress field electrode cracking resistance

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