Diffusion and Regeneration Mechanism of Waste Composite Oils Rejuvenator in Aged Asphalt

The physical performance of recycled asphalt was used as the main evaluation index to study the optimal range of a self-made rejuvenator.Through the penetration,viscosity and gel permeation chromatography (GPC) tests,the diffusion degree of the rejuvenator under different temperatures and time process was analyzed,and the diffusion efficiency of the rejuvenator was evaluated from the macro and micro perspective.The regeneration mechanism of the rejuvenator in the aged asphalt was also analyzed using the Fourier transform infrared spectroscopy (FTIR),scanning electron microscope (SEM) and chemical composition tests.The research results showed that the optimum rejuvenator content was about 3%.Higher temperature and longer time were beneficial to improving the permeability and diffusion of the rejuvenator.During the aging process,the light components were reduced,and more macromolecular asphaltenes were generated as well as a large number of carbonyl and sulfoxide.After diffusion and regeneration,the light components in the asphalt were supplemented,the wrinkles and gullies of the aged asphalt were almost improved to the surface state of the matrix asphalt.     

老化沥青与再生剂混合相行为

采用修正的Flory-Huggins方程计算老化沥青和再生剂的混合自由能并探讨它们之间的相行为。3 种老化沥青的溶解度参数值和芳碳率均比相应的原料沥青高。再生剂R1 与加德士老化沥青在25 ℃时的混合自由 能ΔGM >0,再生剂R1 与加德士老化沥青的混合过程为非自发过程,因此它们之间不能形成均相体系。3种老化沥 青与R2、R3 和复合再生剂在25℃的混合自由能ΔGM <0,混合过程为自发过程,因此老化沥青与R2、R3 和复合再 生剂能形成均相体系。     

Evaluation of Mixture Performance Recycled Asphalt Pavement Materials as Base Layer with or without Rejuvenator into the Asphalt

The binder properties were determined in accordance with Chinese standard such as ductility test,which allowed to measure the distance in centimeters that a standard briquette of asphalt had been stretched before breaking.Then,penetration test was carried out in order to know some properties of the asphalt,which are the hardness and the softness.Finally,softening point test was carried out in order to determine the temperature at which the bitumen attains a particular degree of softening under the specification of the test.According to Chinese standard for performance tests,firstly,Marshall test was carried out in order to measure the theoretical density,air voids,voids filled with asphalt,stability,flow,and voids in mineral aggregate of asphalt specimens.Secondly,Freeze-thaw splitting test was carried out in order to determine Splitting strength ratio.Finally,dynamic stability (rutting) test was carried out to determine average dynamic stability.Beside the tests carried out,the gradation of the extracted aggregate in accordance with American Association of State Highway and Transportation Officials was carried out to determine the dimensions of the particles weight distribution.Furthermore,both the percentage of recycled asphalt pavement materials and binder in mixture were determined to know how much of the new material during the mixture was needed.However,two specimens were used to evaluate the performance of recycled asphalt pavement materials.One specimen of recycled asphalt pavement materials was ten years old,and another one of recycled asphalt pavement materials was five years old.The results show that the conditions of the environment such as moisture,temperature,and age,decrease the ductility and penetration properties of binder when increase the softening point property of binder.Then the gradation of recycled asphalt pavement aggregate is of the required values to reuse in the mixture,while the flow ratio,the splitting strength ratio,and the dynamic stability ratio,are less than the required value test.With regard to the properties of mixture of recycled asphalt pavement material binder with rejuvenator,the results show that when the penetration and ductility versus percentage of rejuvenator increase,softening point versus percentage of rejuvenator decreases.Also,when the bitumen and rejuvenator percentage increase,the air voids decrease.Consequently,voids filled with asphalt and voids in the mineral aggregate increase.Moreover,the theoretical density and stability values decrease in a mixture containing four-point fifty percent to six percent of bitumen and rejuvenator,whereas the flow values increase.More interestingly,with four percent to four-point fifty percent mixture ratio of bitumen and rejuvenator,density,stability,and flow values increase.The splitting strength ratio values of mixtures and the dynamic stability test (rutting test) values of mixtures with forty percent of specimen one and specimen two respectively are greater than the required value of the standard test.In addition,the high percentage of rejuvenator increases the rut of pavement,in the same manner,the low percentage of rejuvenator induces low rut.In conclusion,the binder content from recycled materials without rejuvenator seems not be sufficient to be reused on the new pavement while the aged recycled material seems to be performed better than no aged recycled material with rejuvenator into bitumen.Then,the rejuvenator can influence the bitumen properties and performance of the pavement.Finally,the pavement made by only recycled pavement materials as a base layer appears to be more economical but cannot be more effective than the pavement made by mixture of new and recycled pavement materials as a base layer.     

Compound rejuvenation of polymer modified asphalt binder

The objective of this research was to show a way to conduct rejuvenation of aged polymer modified asphalt binder (PMB) successfully. To fully evaluate and understand the rejuvenation of aged PMB, the Penetration grade tests including penetration, soften point, ductility and elastic recovery and Superpave™ PG grade tests including DSR, BBR and DDT were conducted. The rejuvenation effect of aged PMB by utilizing a fluid recycling agent in common use for binder rejuvenation was evaluated. And then the compound rejuvenation effect of aged PMB by utilizing the recycling agent with a new modifying additive for binder modification was evaluated. The experimental results indicated that the recycling agent in common use currently does not apply to polymer modified asphalt binder rejuvenation. But the recycling agent together with the modifying additive can restore the characteristics of aged polymer modified binder very well. Therefore, compound rejuvenation of polymer modified asphalt binder is recommended.     

How to Make Capsules Containing Rejuvenators for Their Use in Asphalt Concrete

Rejuvenators are products designed to restore original properties to oxidized asphalt binders by restoring the original ratio of asphaltenes to maltenes. But,for a rejuvenator to be successful,it must penetrate the pavement surface. Besides,application of a rejuvenator will also reduce the skid resistance of the pavement. To solve this,these rejuvenators can be encapsulated and mixed in asphalt concrete. Once the stress in the capsules reaches a certain threshold,the particles break and the rejuvenator is released,giving back the original properties of the pavement. The objective of this paper is to show how these capsules behave and define the most appropriate testing methods to find their effect on asphalt concrete. For this,two different types of rejuvenators will be encapsulated and their effect on the properties of the capsules investigated. Besides,the release mechanisms of the capsules will be unravelled.     

微观尺度下生物再生剂?沥青的融合扩散特性

运用分子动力学方法构建生物再生剂?沥青模型,通过微观模拟探究再生剂?沥青的融合扩散行为. 首先采用FTIR试验结合SARA模型确定老化前后的12种沥青分子结构,选用动物废弃物生物再生剂的主要成分类固醇和羧酸,建立沥青?再生剂的扩散体系分子动力学模型. 采用密度、相容性指标验证分子动力学模型的可靠性,分析不同温度、老化状态下生物再生剂在基质沥青与老化沥青中的融合扩散行为. 结果表明:生物再生剂在老化沥青中的扩散系数高于在基质沥青中的扩散系数;在相同温度下类固醇的扩散性能优于羧酸;两种生物再生剂的扩散系数随着温度升高而升高,高温条件下体系动能更大,使体系分子更容易摆脱分子力的约束.     

再生剂对再生沥青感温性的影响

通过3种再生剂对老化沥青进行再生实验,用针入度指数和粘温指数对再生沥青感温性进行评价并讨论再生剂的影响规律。实验结果表明,再生沥青在低温和中高温区的感温性均好于原料沥青,其中再生剂C再生的再生沥青感温性较好;3种再生剂对再生沥青中温区的感温性影响无明显规律,再生剂增加了老化沥青的感温性;再生剂A对再生沥青的高温区感温性有所降低,而再生剂B和C则略有增加。结合再生剂组分分析数据得出饱和分能降低沥青的高温区感温性,而芳香分则增加沥青的高温区感温性。     

植物油再生沥青的性能研究

为了解决矿物油再生技术再生率低、成本高等诸多问题,采用处理过的“地沟油”代替矿物油制备植物油基再生剂对老化沥青进行再生,并通过试验测试了老化沥青再生前后各项性能指标,确定了植物油沥青再生剂的最佳掺量,为再生沥青路面材料设计提供依据。性能试验结果表明：植物油基再生剂不仅可以有效降低老化沥青的黏度,也有利于改善沥青的低温性能,同时有效解决“地沟油”科学利用问题,并显著降低废旧沥青再生成本。     

A new approach for evaluating rejuvenator diffusing into aged bitumen

Rejuvenator diffusing into aged bitumen was evaluated by determining penetration and chemical components of aged bitumen with rejuvenator coat before and after diffusing experiment. Effects of temperature, time and viscosity of rejuvenator on the diffusing ability of rejuvenator into aged bitumen were investigated. Results indicated that the diffusing ability of rejuvenator into aged bitumen could be enhanced with the increasing of temperature and time, however, the diffusing of rejuvenator into aged bitumen would be restricted due to the volatilization of light component and aging of rejuvenator under high temperature (over 170 ℃). Rejuvenator with low viscosity diffused into aged bitumen more easily.     

RANDOM MICROSTRUCTURE FINITE ELEMENT METHOD AND ITS VERIFICATION FOR EFFECTIVE PROPERTIES OF COMPOSITE MATERIALS

The present study aims at developing a new method--Random Microstructure Finite Element Method (RMFEM) for the effective properties of com posite materials.In this method, a random microstructure model is used to simulate the microstructure of the real composite materials.The physical fields in such a random microstructure model under specified boundary and initial conditions are analyzed by finite element method.The effective properties of composite materials can be obtained from the analysis results.As verification, some effective properties of composite materials, such as elastic module.thermal expansion coefficient, thermal conductivity and elastoplastic properties,are investigated by random microstructure finite element method.The numerical results are given together with the experimental data.It is revealed that the random microstructure finite element method is a very valid method for the determination of the effective properties of composite materials.     

Micromechanical analysis of damage evolution in splitting test of asphalt mixtures

A methodology was presented relating the microstructure of asphalt mixtures to their damage behavior. Digital image techniques were used to capture the asphalt mixture microstructure, and the finite element method was used to simulate the damage evolution of asphalt mixture through splitting test. Aggregates were modeled to be linearly elastic, and the mastics were modeled to be plastically damaged. The splitting test simulation results show that the material heterogeneity, the properties of aggregates and air voids have significant effects on the damage evolution approach. The damage behavior of asphalt mixture considering material heterogeneity is quite different from that of the conventional hypothesis of homogeneous material. The results indicate that the proposed method can be extended to the numerical analysis for the other micromechanical behaviors of asphalt concrete.     

有机化累托石改性沥青的制备及性能研究

采用熔融插层法制备了有机化累托石(OREC)改性沥青,利用X射线衍射(XRD)表征了OREC改性沥青的微观结构,研究了OREC用量对改性沥青物理性能和粘度的影响,并通过薄膜烘箱(TFOT)和压力老化(PAV)对基质沥青和改性沥青老化性能进行了比较。结果表明:OREC可与沥青熔融插层形成剥离型纳米复合结构;OREC与沥青熔融共混后,沥青的软化点和粘度均增大;与普通沥青相比,经TFOT和PAV老化后,OREC改性沥青的软化点增量和粘度增加率显著减小,表明OREC可有效改善沥青耐老化性能。     

The Development of Recycling Agent for Asphalt Pavement

A type of recycling agent was developed and its use for modifying used asphalt is described.The results show that the viscosity and three main properties of the aged asphalt were remarkably improved.With 5%-7% content of recycling agent,the main properties of recycled asphalt comported with China GB asphalt standard AH-70 and the recycled asphalt concrete could be used as high-grade highway,Furthermore,the recycling mechanism of the aged asphalt is discussed.     

Fabrication and Microstructure of BN Matrix Composites with Electrical COnductivity

BN ceramic is advanced engineering ceramics with excellent thermal shock resistance,good workability and excellent dielectricity.TiB2 ceramic has excellent electric conductivity,high melting points,and corrosion resistance to molten metal.Therefore,the composite consisting of BN and TiB2 ceramics is expected to have a combination of above-mentionaed properties,thereby can be used as self-heating crucible.In this puper,hot pressing technology was used to fabricate the high performance BN-TiB2 composite materials,microstructure and electric conducting mechanism were studied,and the relationship between the microstructure and physical property was discussed.the results show that the microstructure of composites has a great influence on the physical property of composites.The BN-TiB2 composites with excellent mechanical strength and stable resistivity can be obtained by optimizing the processing parameter and controlling the microstructure of composites.     

橡胶粉与SBS复合改性沥青路用性能与微观结构

采用废旧橡胶粉和热塑性弹性体SBS复合改性道路石油沥青AH-90,分别进行了性能测试试验和结构分析试验,结果表明:改性后沥青的针入度明显下降,延度和弹性恢复明显增加,软化点升高,T800升高,T1.2降低,沥青的高温稳定性和低温变形能力均有较大改善。     

高粘度改性沥青的老化性能研究

分别采用TPS和SBS制备了高粘度改性沥青和普通SBS改性沥青。研究了两种改性沥青在旋转薄膜烘箱(RTFOT)、压力老化箱(PAV)和紫外光老化前后物理性能的变化。结果表明:TPS改性沥青的抗短期热氧老化和长期热氧老化性能优于SBS改性沥青,同时,TPS改性沥青具有良好的抗紫外光氧老化性能。     

PEG/活性炭相变材料改性沥青

利用PEG/活性炭复合固-固相变材料对沥青进行改性,制备出相变材料改性沥青。对不同配比的相变材料改性沥青进行老化、高低温交变等处理,观察其外观,并利用电子拉力试验机和热机械分析仪(TMA)测试改性沥青的延展性、软化点等性能。研究表明,当PEG/活性炭相变材料含量为20%时相变材料改性沥青的延展性最好,相变材料含量为15%~25%时,改性沥青的软化点明显提高。     

基于DMA方法的沥青胶浆微观结构

采用动态力学分析(DMA)方法对沥青胶浆的微观结构进行了研究,通过对沥青胶浆的动态黏弹性能的变化规律以及Han曲线的温度依赖性进行分析。比较了沥青胶浆和改性沥青胶浆的相态结构的区别,并且根据沥青及沥青矿粉胶浆的损耗因子tanδ计算出参数A,用来评价沥青与胶浆的界面粘结程度。研究结果表明了用DMA方法可以很好地研究沥青胶浆的微观结构,从而为更好地改善沥青胶浆的路用性能提供了理论依据。     

SBS/HON复合改性沥青流变性能

为了研究SBS(styrene-butadiene-styrene)/HON(Honeywell TitanTM)复合改性沥青的流变性能,选取2种SBS和2种HON改性剂制备复合改性沥青,采用布氏旋转黏度计分析了复合改性沥青的黏温性能,采用动态剪切流变仪(DSR)、低温弯曲流变仪(BBR)分别评价复合改性沥青的高温及低温流变性能.结果表明:HON可有效改善沥青的黏温性能,降低施工温度,并可提高沥青的高温流变性能;SBS可明显改善沥青材料的高温流变性能,并可在一定程度上提高沥青材料的低温流变性能.     

Delaunay三角网格的沥青混合料粗集料分布特性

为研究沥青混合料的细微观结构特征,提出粗集料分布特性的量化方法和指标.基于数字图像处理技术对粒径大于2.36 mm的沥青混合料粗集料质心进行delaunay三角剖分,建立三角单元内A1/A2（集料-胶浆面积比）参数表征细观结构局域特征,通过对A1/A2统计特性的描述、分析以及概率形式的统计推断,得到粗集料整体分布特性的量化与分析结果.研究表明,不同级配之间粗集料的总量及级配各档位质量分布的差异性将显著影响细观结构特征,如沥青玛蹄脂碎石混合料（SMA）、开级配抗滑磨耗层混合料（OGFC）和高性能路面沥青混合料（SUP） 3种级配粗集料的平均紧密程度呈递减趋势.此外,给出A1/A2参数的集中趋势指标和偏态指标,并在此基础上提出非参数检验方法对沥青混合料细观结构进行对比,评判多种级配细观结构的嵌挤紧密特征的异同,认为SMA和OGFC的细观嵌挤特征类似,而SUP和SMA以及OGFC相比细观结构更趋于分散.