再生剂渗透再生机理及其影响因素研究

基于复合材料理论和Fick扩散定律,计算得出扩散系数直观地评价了各因素对再生剂渗透扩散性能的影响,结果表明:随着时间的延长,扩散程度加深,扩散系数减小;温度对扩散性能影响显著,温度升高,扩散系数增大;随着与再生剂和老化沥青初始界面距离的增加,扩散系数明显的减小,25 mm处再生剂浓度很低,扩散系数趋近于0;粘度越低的再生剂,扩散性能越强,170℃或者更高的温度,低粘度的再生剂会发生挥发现象.最后,根据研究结果对实际工程中再生混合料的拌和工艺提出了改进意见.     

新旧沥青界面融合实测与耗散粒子动力学模拟

为扩充新旧沥青界面再生融合特征的研究手段,多尺度量化剖析新旧沥青界面再生融合速率、融合程度等行为参数,通过动态剪切流变试验,基于细观尺度实测研究新旧沥青界面再生融合规律;通过耗散粒子动力学,基于介观尺度模拟研究新旧沥青界面再生融合机理行为并验证动态剪切流变试验实测结果。分析表明:加热温度、加热时间均与新旧沥青界面再生融合程度呈正相关关系,加热温度与新旧沥青界面再生融合速率呈线性正相关关系,加热时间与新旧沥青界面再生融合速率呈指数负相关关系;加热时间从10~120 min,沥青界面扩散激活能增长了3~5倍;采用新添沥青单一调和的方式再生效果不佳,各试验条件下沥青界面再生融合程度均不足50%,但采用新添沥青与再生剂复合的方式,新旧沥青界面再生融合程度提升2倍左右,并同比降低沥青界面扩散激活能10%~30%;剪切速率可较大幅度影响新旧沥青界面再生融合作用,并且相比于较高加热温度(358~418 K),在低温加热条件下(298~358 K)适当增加剪切速率对改善新旧沥青界面再生融合特征效果更明显;采用的沥青四组分分子结构模型、构建的耗散粒子动力学粗粒化结构模型和选取的模拟计算参数为跨尺度拓展量化表征新旧沥青界面再生融合行为特征与规律提供重要支撑。     

辽河AH-90#沥青老化组分变化研究

笔者结合沥青路面再生利用中的热点问题,采用理论分析与实验数据相结合的方法,阐述了基质沥青老化的原理以及组分、性能的变化规律.结果表明,沥青在老化过程中,饱和分含量变化幅度不大,芳香分的含量逐渐减小.胶质含量总的趋势是下降,不断转化为沥青质.而沥青质含量不断呈增大的趋势.随老化时间的延长和老化温度的升高,沥青的胶体不稳定指数逐渐增加.本研究旨在探讨沥青老化组分变化规律,为沥青再生技术提供理论依据.     

再生剂与老化沥青微观作用机理

采用分子动力学模拟方法,根据老化沥青体系溶解度参数变化规律,研究了再生剂组分对老化沥青相容性的影响;通过体系的相互作用能分析,探讨了再生剂组分对老化沥青再生的作用机理。结果表明,芳香分有助于改善老化沥青的相容性,且芳香分掺量越大改善效果越好;饱和分则刚好相反,这与实验结论相一致。芳香分与老化沥青相互作用能随掺量增大而急剧增大,意味着两者相互吸引作用显著增强,其原因在于静电相互作用能占据主导地位,范德华相互作用能相对较小;然而饱和分与老化沥青的相互作用能随掺量变化不大,其中静电相互作用能和范德华相互作用能几乎各占一半贡献。分子间的静电相互作用能是影响老化沥青再生的主要因素。     

再生剂对老化沥青性能影响的研究

通过室内沥青加速老化试验,实验室制备了经薄膜烘箱老化(TFOT)、压力老化(PAV)和紫外老化(UV)的沥青样品。随后,在老化沥青中加入了两种不同的再生剂进行老化沥青的养护再生并在室温条件下养护3d。对基质沥青、老化沥青、再生沥青进行了针入度、软化点、延度的测试。结果表明,两种再生剂都能使老化沥青性能得到一定的恢复,对老化沥青均有再生功能,但是再生剂1具有比再生剂2更好的再生效果。通过对老化沥青进行了不同剂量再生剂1的掺加试验,借助流变性能测试,根据试验结果确定了再生剂1的最佳掺量为6%。     

生物沥青再生沥青结合料使用性能

为研究生物沥青用作沥青再生剂的可能性,选用蓖麻油生物沥青为再生剂制备再生沥青,并通过试验研究了旋转薄膜烘箱(rolling thin film oven,RTFO)老化前后该种生物沥青掺量对再生沥青相关技术指标的影响.结果表明:随着生物沥青掺量的增加,再生沥青针入度增大,软化点降低,30%掺量的生物沥青可将老化沥青的针入度恢复到原样沥青水平.然而,生物沥青对延度的改善较差.此外,再生沥青135℃黏度、当量软化点和当量脆点降低,针入度指数PI和塑性温度范围逐渐增大,RTFO老化后残留针入度比减小,软化点增量、黏度老化指数逐渐增大.生物沥青的加入改善了再生沥青的感温性能和低温性能,对高温性能表现出不利影响.随着生物沥青掺量的增加,再生沥青抗老化性能逐渐减弱,但在30%掺量范围内,生物沥青再生沥青的抗老化性能仍不低于原样沥青水平.     

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。     

SBS改性沥青老化模拟及再生研究

为研究不同再生方式对老化SBS改性沥青性能影响情况,首先通过常规试验、SHRP试验选择恰当的SBS改性沥青老化模拟方式;然后对4种再生方式:Ⅰ、掺加SK-90号基质沥青;Ⅱ、掺加SBS改性沥青;Ⅲ、掺加再生剂;Ⅳ、掺加再生剂+90号基质沥青展开探讨,确定了各再生方式的最佳条件,比较了各再生方式的优劣差异.试验结果表明:采用RTFOT试验进行老化模拟更加方便、科学,RTFOT试验5 h获得的改性沥青指标与服务年龄为7 a的SBS改性沥青一致;4种再生方式对老化沥青性能均有改善作用,且每种方式的新、旧沥青最佳比例及添加剂最佳掺量均不相同,在各自最佳条件下比对4种再生方式知,最优再生方式为Ⅱ,然后依次为Ⅲ、Ⅳ、Ⅰ.     

抗紫外光老化剂对民用机场沥青道面用沥青性能的影响

为了解决机场沥青道面紫外光老化问题,通过分析受阻胺类老化剂对强紫外线辐射下基质沥青和SBS改性沥青高温、疲劳及老化性能的影响,提出了采用受阻胺类老化剂解决沥青老化问题的方法.采用旋转薄膜烘箱试验模拟沥青短期老化及室内紫外光老化箱模拟沥青长期老化,研究了受阻胺类老化剂GW-944对光老化前后沥青性能的影响.试验结果表明:GW-944光老化剂对基质沥青高温性能改善效果欠佳,GW-944光老化剂能显著改善SBS改性沥青性能,其光老化后的疲劳、高温和抗老化能力得以提升.该抗紫外光老化剂对SBS改性沥青进行综合性能改善时,建议使用0.7%掺量.     

SBR改性沥青老化动力性能

目的通过研究SBR改性沥青的老化动力性能,进一步探讨在动力因素的影响下沥青和骨料的黏附性.方法通过旋转薄膜烘箱试验,研究SBR改性沥青和基质沥青在不同老化温度、老化时间下的软化点变化规律,并以软化点为参数建立了SBR改性沥青老化动力学模型,以此研究SBR改性沥青的老化动力性能.结果与基质沥青相比,SBR改性沥青在150℃、163℃、180℃三个老化温度下的老化反应速率常数分别降低了26.8%、51.9%、21.4%;SBR改性沥青的反应活化能达到48.863 kJ·mol^-1,比基质沥青提高了13.1%.结论以软化点为参数建立的沥青老化动力学方程能够较好的反映沥青的老化过程,SBR改性沥青比基质沥青具有较好的抗老化性能.     

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。     

Effect of rejuvenators on performance and microstructure of aged asphalt

A composite rejuvenator was used for the rejuvenation of aged asphalt in comparison with the common rejuvenator. The effects of the rejuvenators on the performance and microstructure of the aged asphalt were investigated by physical properties tests, dynamic shear rheometer and atomic force microscopy. The results indicate that the physical and rheological properties of the aged asphalt are restored more significantly by the composite rejuvenator than the common rejuvenator, which can be ascribed to the effective recovery of microstmcture of the aged asphalt. The composite rejuvenator has the potential to be used for the rejuvenation of severely aged asphalt since it can restore the colloidal structure of the aged asphalt effectively through composition regulation and chemical reactions between the composite rejuvenator and asphaltenes.     

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.     

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.     

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.     

非线性微分动力学模型的沥青老化行为

为了研究沥青的老化行为及抗老化性能,将沥青进行旋转薄膜烘箱老化（RTFOT）和60℃烘箱老化试验,并从不同使用年限的路面回收老化的沥青,采用非线性微分动力学模型对不同老化方式的沥青粘度进行拟合,根据模型参数讨论了沥青在不同老化条件下的性质变化和老化速率,并分析了老化机理的差异。结果表明,非线性微分模型可以有效地模拟沥青室内和野外老化进程,模型参数L和r可以实现对老化状态和老化速率的量化。不同老化温度下,沥青都有其对应的极限老化状态。RTFOT老化与野外老化的极限老化程度约为60℃烘箱老化的4～5倍,RTFOT老化6h与野外老化6a的老化效果接近,延时的RTFOT老化方法可以模拟实际路面沥青的长期老化。     

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.     

沥青紫外光老化特性及机理探讨

为了研究沥青紫外光老化行为及机理,采用两种沥青进行室内模拟光老化试验.通过对沥青不同老化时间的黏度和延度时比分析,研究了沥青紫外光老化的高低温性能衰变行为,并采用组分试验、胶体结构以及红外光谱(IR)分析,探讨了其微观变化及老化机理.结果表明,紫外光老化主要发生在沥青表面,导致沥青的低温性能大幅衰减.对高温性能的影响相对较小;沥青中的芳香分和胶质对紫外光较为敏感.容易发生光氧化反应生成沥青质,胶体不稳定指数和相对羰基指数均不断增大,沥青性能不断劣化.     

AH-90及PG70-28改性沥青老化性能研究

对AH-90基质沥青及PG70-28改性沥青分别进行了室内旋转薄膜烘箱老化、压力老化及室外光氧老化试验,采用针入度、针入度指数、延度、软化点等指标分析考察了室内热氧老化对沥青高温稳定性、低温开裂性及温度敏感性能的影响。结果表明:老化降低了沥青的低温抗裂性能,改善了沥青的抗高温变形性能和对温度的敏感性,改性沥青的抗老化性能明显优于基质沥青。采用粘温指数法、老化指数法分别考察了光氧老化及热氧老化沥青的感温性能和抗老化性能。结果表明,粘温指数法和针入度指数法具有较好的相关性,总辐射能为10.5 kJ/cm2的室外紫外光照射对沥青感温性能和路用性能的影响比PAV老化严重,在内蒙古强紫外线地区沥青路面设计时需充分考虑光老化带来的危害。