Rheological properties of conductive asphalt binders containing graphite and carbon fiber before and after ageing

Modified asphalt binders were prepared by adding conductive materials, graphite and carbon fiber. The rotation thin film oven test (RTFOT) and pressure age vessel test (PAV) were conducted to simulate the binder aging in the field. Rheological properties of graphite and carbon fiber modified asphalt binder were investigated by the empirically rheological properties (penetration and softening point) and the dynamic shear rheometer (DSR) test. Results show that physical properties of asphalt binder change with conductive material mixed. DSR tests present that the values of complex modulus increase while phase angles decrease under a proper amount of graphite and carbon fiber. Rutting parameters point out that graphite can improve the rutting resistance of asphalts. Rheological parameters can be used to assess aging.     

Evaluation of Layered Inorganic Nano-powder Modified Bitumen

Thermal oxidative and aging as an inevitable process in the practical application of road asphalt has great effect on the properties of asphalt. In this paper,the influences of short-term thermal oxidative ageing and ultraviolet radiation(UV) aging on the dynamic viscosity,penetration,softening point and rheological properties of two kinds of layered inorganic nano-powder including organo-modified montmorillonite (OMMT) and nanometer brucite (Mg(OH)2) modified asphalts were studied respectively. The rheological properties of these binders have been determined using a dynamic shear rheometer (DSR) through temperatures sweep tests.The rheological and physical analysis showed the two major influences of ageing on the properties for two kinds of layered inorganic nano-powder modified bitumens. On one hand,ageing decreased the viscous behaviors of modified binders,on the other hand,ageing improved the elastic behaviors of modified binders. The performances of binders after aging depended on the combined effect between the modifier and the bitumen. Both the two modifiers resisted the aging of bitumens and the effect of OMMT was better.     

Property of Anti-Ultraviolet Aging of LDHs Modified Asphalt

LDHs was introduced into 70# asphalt binder by different weight ratio. Asphalt penetration test, soft point test, ductility test, viscosity test, dynamic shear rheometer (DSR) test and Fourier transform infrared (FTIR) test, were conducted to characterize and predict the LDHs modified asphalt. Research results indicated that the LDHs has great effect on resistance to UV of asphalt, which makes the asphalt absorb less ultraviolet radiation under the same UV intensity. Complex modulus, phase angle and FTIR test results indicate that the LDHs can significantly enhance the property of anti-ultraviolet aging of asphalt. The test results show that the LDHs has an obvious improvement on the anti UV aging of asphalt.     

基质沥青老化行为与老化机理

在环境作用下沥青易产生静态硬化和氧化硬化,使沥青的流变特性发生改变,而严重影响沥青路面的耐久性,如何合理评价和选择沥青对确保路面使用品质至关重要.通过3种不同基质沥青的组分分析和不同老化状态下沥青的常规试验(针入度、软化点和延度试验)、SHRP试验(DSR(Dynamic Shear Rheometer)和BBR(Bending Beam Rheometer)试验)结果比较,结合FTIR(Fourier Transform Infrared)红外光谱试验结果,分析了不同老化状态下基质沥青的老化特性和机理.结果表明,常规试验可用来描述基质沥青老化前后性能变化,但它只能提供特定温度荷载频率下的试验信息,而SHRP试验可全方位反映沥青老化对沥青流变行为的影响,建议采用SHRP流变学指标特别是BBR试验结果评价沥青的老化特性.     

废橡胶粉对SBS改性沥青的老化性能影响研究

在SBS改性沥青中加入糠醛抽出油溶胀后的活化废橡胶粉制备SBS／胶粉复配改性沥青,并对其热老化前后的软化点、针入度、延度等性能进行测试,表明在SBS改性沥青中加入胶粉并不影响改性沥青的热老化性能,而且对改性沥青的耐热老化性能还有一定程度的提高．对几组复合改性沥青的紫外线老化试验也表明加入废橡胶粉能够提高改性沥青的抗紫外老化性能．     

SBS改性沥青的老化方程及应用

建立起SBS改性沥青的非线性微分老化方程,应用微分方程探索SBS改性沥青的老化规律,并计算任意时刻的沥青老化量和老化速率;测定SBS改性沥青在不同RTFOT老化时间下的针入度、5℃延度、软化点、135℃粘度指标,得出各指标的老化参数及老化方程,通过分析实验值与老化方程计算值间的相关性,验证非线性老化方程的可靠性;对老化方程的潜在应用方向进行了初探。研究结果表明:非线性老化方程能精确地预测SBS改性沥青的针入度、软化点、粘度、延度的老化规律,能计算任意时刻各指标的老化量及老化速率;老化速率方程计算显示,沥青的老化速率在开始时刻最大,后期随老化时间的延长而逐渐变小,与老化的实际情况吻合;沥青老化方程可用于沥青抗老化性能评价、耐久性评价、沥青路面开裂预测、沥青路面再生决策。     

I-C级克拉玛依SBS改性沥青的制备

采用添加硬沥青、石油树脂和助剂的方法制备了I-C级克拉玛依SBS改性沥青,考察了硬沥青、石油树脂以及助剂对SBS改性沥青软化点、针入度以及储存稳定性的影响。结果表明,当改性剂SBS质量分数为4%、硬沥青质量分数为3%、石油树脂质量分数为3%、助剂质量分数为2%时,SBS改性克拉玛依沥青的软化点为55.6℃,针入度为60.7（0.1mm）,5℃时延度达到31.2cm,在163℃的温度下储存48h时,上、下层软化点之差为1.2℃,符合I-C级改性沥青标准要求。     

沙特沥青老化动力学研究

研究了用沙特减渣调配出的两种高等级道路沥青,在老化过程中正戊烷沥青质的变化及针入度、软化点、延度等指标的变化。并根据正戊烷沥青质的变化,进行了沥青老化动力学研究,计算得到了有关动力学参数,得出了动力学方程,计算值与试验数据相吻合,初步揭示了沥青组成与其抗老化性能之间的关系。结果表明,高等级道路沥青老化属于一级动力学反应。与AH-90相比AH-70沥青具有较高的反应活化能,反应速度常数较小,具有较低的老化速率和较好的抗老化性能。同时,老化过程中,沥青针入度、软化点及延度的变化进一步证明了所得动力学模型是可靠的。     

有机化蒙脱土对SBS改性沥青热氧老化性能的影响

将有机化蒙脱土(OMMT)与SBS改性沥青熔融共混,制备了OMMT/SBS改性沥青。利用X-射线衍射(XRD)分析了OMMT/SBS改性沥青的微观结构。通过长期热氧老化实验研究了OMMT对SBS改性沥青热氧老化行为的影响。XRD分析表明,OMMT/SBS改性沥青形成了剥离型纳米复合结构。热氧老化试验结果显示,OMMT可显著减少SBS改性沥青软化点和粘度的增加,提高其残留延度比和残留针入度比,明显改善了SBS改性沥青耐热氧老化性能。     

泡沫温拌再生沥青高低温性能研究

为研究回收沥青掺量对泡沫温拌沥青高低温性能的影响,分别对掺加0%、20%、40%、60%、80%回收沥青的泡沫温拌沥青进行软化点、DSR和BBR试验。试验表明:随着回收沥青掺量的增加,泡沫温拌再生沥青的软化点、车辙因子和破坏温度值逐渐升高;当回收沥青的掺量达到60%及以上时,泡沫温拌再生沥青胶结料的高温性能明显改善;胶结料试样的低温抗裂性能随着回收沥青掺量比例的增加而逐渐降低,当回收沥青的掺量大于40%时,泡沫温拌再生沥青的蠕变劲度S和蠕变速率m值不能满足规范要求,低温抗裂性能较差;建议回收沥青的掺量小于60%。     

超硬质沥青改性结合料流变性能分析

为研究超硬质沥青(super hard asphalt,SHA)对超硬质沥青结合料的高、低温流变的影响效果,采用SHA作为改性剂对AH-90道路石油沥青进行改性,制备了不同质量分数（5%、6%、7%和8%）的SHA改性结合料,并进行动态剪切流变试验、多应力蠕变恢复试验及小梁弯曲蠕变试验. 试验结果表明:其适用于时温等效原理;SHA的掺入会有效提高沥青结合料的车辙因子G^*/sin δ,沥青混合料的高温性能得到明显改善;随着SHA掺量的增加,沥青结合料的平均应变恢复率R逐渐升高,不可恢复蠕变柔量J_nr逐渐降低,掺加SHA有利于提高沥青结合料高温抗变形能力与变形恢复能力;随着SHA的掺入,沥青结合料的蠕变劲度S与蠕变劲度变化率m变化幅度不大,对沥青结合料的低温抗裂性能影响不大. SHA改性沥青结合料高温抗车辙性能优异,低温性能相对于基质沥青PG分级保持不变.     

水泥代替矿粉对沥青混合料性能的影响分析

通过分析矿粉和水泥在沥青混合料中的作用机理,分别以不同比例的水泥代替矿粉,对沥青胶浆做延度、软化点、DSR、BBR等试验;同时,以AK-16和SAC-16为例,用不同比例的水泥代替矿粉,分别做浸水马歇尔试验、单轴压缩试验、动稳定度等试验,分析水泥代替矿粉后对沥青混合料的高、低温性能和水稳性等性能变化。试验结果表明,以一定比例的水泥代替矿粉可以有效的改善沥青混合料的性能。     

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.     

Research on UV Aging Characteristics of Inorganic Powder Modified Asphalt Binders

Asphalt binders tend to age when exposed to ultraviolet radiation (UV) and high temperature. Asphalt modification is an effective method to improve the performances of asphalt materials,in which inorganic powders modified asphalts are useful and lowly cost. In this study Organic montmorillonite(OMMT),Magnesium hydroxide(Mg(OH)2) ,mineral filler are used as nano-powder modifiers while these three modified asphalts as well as matrix asphalt are used in the UV-based aging experiments. Aging performances are appraised by means of dynamic rheometer tests. In the simulation experiments,these two kinds of asphalt membrane,while different dosages of the modifier(0%,2%,4%),would be put into the UV aging box for 24 h.In additional different UV-aging times while the same dosage of the modifier are also researched. By exploring some new measures to evaluate UV-aging,the OMMT modified asphalt binder and Mg(OH)2,which has the layered structure,were found to have a certain ability to restraint ultraviolet radiation. The results show that longer aging time performed more serious UV-aging,more contents of modifier performed a better resistance to UV-aging while the OMMT exhibited a better resistance to aging than Mg(OH)2 modified asphalts.     

Self healing capacity of asphalt binders

To test self healing capability of asphalt binders,three asphalt specimens(pure asphalt,modified asphalt and aged asphalt) were prepared.Every specimen was tested by dynamic shear rheometer(DSR).The temperature sweeps result indicates that both aging and SBS modifying influence the self healing capability of asphalt binder.The fatigue-heal-fatigue test was introduced to study the self healing capability of asphalt in its serving periods.Furthermore,three different periods(0.5 h,1 h,3 h) were set up to study the influence of rest time on fatigue time.It is concluded that longer rest time,less load will delay the appearance of cracks and extend the service life of asphalt binders.     

沥青低温粘弹性能的预测

鉴于弯曲梁流变仪和动态剪切流变仪在研究沥青低温粘弹性能时存在一定局限性,通过动态剪切流变仪测定常温下沥青的动态粘弹性能,利用时温转换原则和沥青动静态粘弹函数的转换关系,转换为沥青的低温粘弹性能,与弯曲梁流变仪在低温下直接测定的低温蠕变性能相比较,分析了两者试验结果的相关性。结果表明,通过常温下沥青的动态粘弹性能可以很好地预测沥青的低温粘弹性能,并且可以得到更宽广的时间范围内沥青的低温粘弹性能。     

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.     

木质素纤维在沥青混合料中的应用

系统分析了木质素纤维沥青胶浆及其沥青混合料的路用性能，包括木质素沥青胶浆软化点，锥入度，动态剪切，网蓝析出试验，混和料马歇尔稳定度、水稳定性、高温稳定性、低温抗裂性及耐疲劳性能，探讨了木质素纤维增强沥青混合料的强度形成机理；并与无纤维密级配沥青混凝土进行了对比、分析．结果表明，木质素纤维能够提高沥青胶浆软化点、剪切强度，改善温度稳定性；木质素纤维沥青混合料具有较好的路用性能．     

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。     

Mixture Performance of Bitumen Modified with Cocamide Diethanolamide

Bituminous binders have been modified by using cocamide diethanolamide.The chemical material used in this study is used for the first-time on the purpose of modification of the bitumen.In addition to the conventional bitumen tests (penetration,softening point and ductility tests),adhesion and peeling tests (Vialit,Nicholson and California tests) were carried out on the bituminous binders which are modified with different ratios of cocamide diethanolamide.According to the results of the tests,the most appropriate additive ratio has been determined.Samples containing the reference bituminous binder and the bituminous binder modified with the most appropriate cocamide diethanolamide ratio were prepared using the superpave volumetric mix design method (SuperpaveTM).In accordance with standard method of test for resistance of compacted asphalt mixtures to moisture-induced damage (AASHTO T 283),the moisture susceptibility of prepared samples has been examined.In order to observe the changes in strength due to the temperature difference,prepared samples were subjected to the freeze-thawing test in accordance with standard test method for resistance of concrete to rapid freezing and thawing (ASTM C 666).