基于动态老化方程的沥青抗老化性能对比研究

对4种沥青进行不同时间的RTFOT老化试验,采用动态方程进行拟合,得到了沥青针入度、延度、软化点、黏度的老化参数和老化方程;以针入度、延度、软化点、黏度的老化参数L和r为评价指标,采用灰色关联理论综合评价不同沥青的抗老化性能.结果表明：针入度、软化点、延度和黏度与老化时间存在非线性关系,在初始期,老化速率大,随着时间的推移,老化速率趋于缓慢;沥青的老化过程可用动态方程表征,其老化参数L和r能很好表征老化度和老化速率,不同沥青、不同指标的老化参数排序不一致;采用灰色关联理论评价4种沥青的抗老化性能排序为：室内制备改性沥青＞90#A级基质沥青＞成品改性沥青＞70#A级基质沥青.     

基于动态老化过程的沥青抗老化性能对比研究

旨在运用动态表征模型评价沥青的老化过程,并采用多指标评价方法对比不同沥青的优劣。对4种沥青进行不同时间的RTFOT老化试验,采用动态表征模型拟合,得到沥青针入度、延度、软化点和粘度的老化参数和老化方程;采用灰色关联决策评价方法,以沥青针入度、延度、软化点和粘度的老化参数L和r为评价指标,综合对比不同沥青的抗老化性能。研究结果表明：沥青针入度、软化点、延度和粘度与老化时间存在非线性关系,在开始时刻,老化速率大,后期随着时间的推移,老化速率趋于缓慢,最后达到平衡;沥青的老化过程可用动态模型表征,参数L和r能很好地表征沥青老化过程的老化度和老化速率,不同沥青的不同指标的老化参数排序不一致;采用灰色关联决策评价四种沥青的抗老化性能排序为：室内制备改性沥青优于90号A级基质沥青优于成品改性沥青优于70号A级基质沥青。     

老化作用下沥青混合料的疲劳及自愈合性能

通过四点弯曲疲劳试验,分析了老化作用下苯乙烯-丁二烯-苯乙烯三嵌段共聚物(SBS)改性沥青混合料和基质沥青混合料的疲劳及自愈合性能.结果表明:老化作用显著削弱了沥青混合料的抗疲劳性能,SBS改性沥青混合料的抗疲劳性能优于基质沥青混合料;老化程度和损伤程度对沥青混合料的自愈合能力影响最为显著;适当延长愈合时间和适宜的愈合温度可以提高沥青混合料的愈合率,但老化程度和损伤程度会削弱其自愈合能力;未老化条件下,基质沥青混合料的自愈合能力大于SBS改性沥青混合料,而老化条件下SBS改性沥青混合料表现出较强的自愈合能力.因此选用SBS改性沥青混合料作为路面材料可以提高沥青路面的抗疲劳及自愈合性能.     

基于重复蠕变的改性沥青非线性黏弹响应分析

对4种改性沥青和1种基质沥青进行高温条件下较宽应力范围的重复蠕变试验,计算不同温度和应力水平下的不可恢复蠕变柔量Junr,分析改性沥青黏弹响应从线性到非线性的变化规律,再选择夏季沥青路面典型高温下沥青非线性响应区域内的Junr值,与沥青混合料车辙试验结果进行相关性分析.结果表明：随着温度升高,沥青的线性范围明显减小;进入非线性响应区域后,Junr值迅速增大,沥青抗永久变形能力明显降低;改性沥青的高温性能在不同温度和应力水平下存在差异,在较高温度和应力下,高强改性沥青的高温性能最优;有限样本条件下,沥青在非线性响应区域内的Junr值与沥青混合料车辙试验结果相关性较好,说明沥青混合料永久变形与沥青非线性黏弹响应关系密切.     

2种改性剂对沥青表面形貌的影响

为了研究改性剂对沥青表面形貌的影响,利用原子力显微镜(AFM)对基质沥青、SBS改性沥青以及Sasobit改性沥青老化前后的表面形貌进行测试.结果表明:SBS改性沥青"蜂状结构"数量及所占面积比基质沥青更小,表面更粗糙,Sasobit改性沥青"蜂状结构"为细长形,数量很少,表面粗糙度很大;3种沥青老化后"蜂状结构"均表现为体积增大,数量增加,表面粗糙度增大;SBS改性剂可以提高沥青的高温稳定性及短期抗老化能力;Sasobit改性剂能够改变沥青的晶体结构分布,提高沥青抗老化性能;单个"蜂状结构"平均面积变化情况能较好地评价沥青老化特性.     

不同试验方法的老化沥青疲劳性能研究

通过旋转薄膜烘箱试验(RTFOT)和压力老化试验(PAV),对70~#基质沥青、苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性沥青、高黏沥青(HV)和基于化学改性原理的SBS/橡胶复合改性沥青(SRC)进行短期老化和长期老化,采用温度扫描试验、时间扫描试验、多重应力蠕变恢复(MSCR)试验和线性振幅扫描(LAS)试验对4种沥青的疲劳性能进行了研究.结果表明:SRC沥青的疲劳性能和抗老化能力最佳;温度扫描试验不能很好地区分不同沥青的疲劳性能差异;时间扫描试验可有效表征4种沥青的疲劳性能,但其耗时较长;MSCR试验中出现了平均弹性恢复率(R_(0.1)和R_(3.2))在长期老化之后大于短期老化之后的情况,其指标规律性和适用的沥青范围尚不明确;LAS试验可以表征沥青在重复荷载作用下的累积损伤发展过程,得到的损伤特征曲线和疲劳方程可有效评价各种沥青的疲劳性能.     

多尺度纳米材料对沥青流变和老化性能的影响

采用布氏旋转黏度、动态剪切流变和弯曲梁流变试验,同时结合红外光谱试验对比研究了多尺度纳米材料对不同老化状态下4种沥青——SK-70和Alfa-70基质沥青、SBR和SBS改性沥青(SBRMA, SBSMA)流变性能的影响.结果表明:4种沥青经多尺度纳米材料改性后,布氏旋转黏度、复数模量及车辙因子均得到不同程度的提高;长期热氧和光氧老化后的疲劳因子降低,即抗疲劳性能得到改善,且对SBRMA的改善最明显.相比未改性沥青,多尺度纳米材料改性后4种沥青在各种老化方式下的复数模量老化指数均降低,而且SBSMA和SBRMA这2种聚合物改性沥青老化前后的丁二烯指数差值也降低,即4种沥青的耐热氧和耐光氧老化性能同时得到有效改善,且对SBRMA的改善效果最好.多尺度纳米材料提高了2种基质沥青的低温连续等级温度,但同时在一定程度上降低了2种聚合物改性沥青的低温连续等级温度.     

纳米TiO2/玄武岩纤维复合改性沥青抗老化性能研究

为了更好地提高沥青的抗老化性能，选用纳米TiO₂和玄武岩纤维作为改性剂，对基质沥青进行了改性。采用动态剪切流变仪对基质沥青与改性沥青进行了流变学试验，通过温度扫描得出了复数剪切模量(G*)和相位角(δ) 2个重要参数，并进行了老化指标的计算，最后综合评价了纳米TiO₂/玄武岩纤维复合改性沥青的抗老化性能。研究发现，纳米TiO₂和玄武岩纤维复合掺入后，改性沥青的高温性能和抗老化性能明显改善。     

新疆地区沥青路面材料高温力学性能研究

在室内模拟极端高温环境的条件下,应用动态剪切流变仪,对?种新疆地区常用的沥青进行试验,得到沥青老化前后复合剪切模量和抗车辙因子;通过旋转压实仪钻芯取样,对?种沥青混合料进行单轴压缩动态模量试验。试验发现,对沥青结合料来说,改性沥青较基质沥青对老化有更高的敏感性,且老化能够显著提高改性沥青的高温抗剪性能;就沥青混合料而言,动态模量可以更好的反应沥青混合料在不同温度、荷载条件下的力学性能。     

竹类生物油改性沥青的抗老化性能

文中旨在研究由竹类生物质慢速热解生物油改性沥青的抗老化性能。将基质沥青与生物油（0%、6%、12%）拌合制备生物沥青,并对生物沥青进行老化试验。采用傅里叶变换红外光谱法对老化和未老化沥青进行测试,通过计算沥青的羰基指数、亚砜指数以及老化活化能,分析发现生物沥青的亚砜指数低于基质沥青,同时生物沥青的老化活化能高于基质沥青。表明生物沥青具有比基质沥青更好的抗老化性能。     

废机油残留物再生沥青的抗老化性能

以废机油残留物(REOB)作为沥青再生剂,从REOB自身、REOB再生沥青及REOB再生沥青混合料3个层次进行老化性能研究.通过延时薄膜烘箱老化试验(TFOT)(老化时间分别为5、10、15、20、25 h),测定了REOB再生沥青、RA5再生沥青和基质沥青的质量及黏度变化,并采用弯曲梁流变试验评定3种沥青老化后的低温...     

Laboratory evaluation of antioxidants for asphalt binders

A laboratory study was carried to investigate whether certain antioxidants could be used to reduce age-hardening in asphalt binders. Several additives including: Vitamin E, Irganox 1010, Irgafos P-EPQ, carbon black, hydrated lime, and DLTDP/furfural, were evaluated. The modified asphalt binders were subjected to two accelerated oxidative aging regimes in the laboratory. Short-term oxidative aging of the binders was simulated using a rolling thin film oven while long-term aging was performed using a pressure aging vessel. The effects of aging on the binders were evaluated based on changes in rheological properties of asphalt binders undergoing oxidative aging. Binders modified with a combination of furfural and DLTDP was found to posses the lowest aging index. The antioxidant-treated binders exhibited improved performance at both high and low pavement temperatures.     

Characterization of warm mix asphalt binders containing artificially long-term aged binders

Reclaimed asphalt pavement (RAP) comprises one of the largest recycled materials, and warm mix asphalt (WMA) technologies become more commonly used due to their promising advantages in the United States and Europe. This paper addresses the laboratory investigation of performance properties of WMA binders containing aged binders. The recycled binders with the additives were produced using two (i.e., zeolite Aspha-min^® and wax Sasobit^®) of the available warm asphalt processes. The recycled WMA binders were artificially short-term and then long-term aged through the rolling thin film oven (RTFO) and pressure aging vessel (PAV) procedures. Superpave binder tests were carried out on the binders through the rotational viscometer, the dynamic shear rheometer (DSR), and the bending beam rheometer (BBR). In general, the results of this study indicated that (1) the additives and aged binders played an important role in determination of the binder properties; (2) the use of lower PG grade as a virgin binder (PG 58-28 in this study) was critical on offsetting the increase of binder stiffness caused by the addition of WMA additives and aged binders; and (3) even at the low recycling percentage of 15%, the lower PG grade was needed to get the results meeting current Superpave binder requirements.     

全气候沥青混合料中老化沥青的微观性能非线性模型

采用凝胶渗透色谱(GPC)和傅里叶红外光谱(FTIR)技术,分别从功能团和分子水平角度,探索了沥青混合料AC-13,SMA-13,SUP-13在全气候多因素综合加速老化条件下沥青的内在老化规律.阐述了沥青老化时的微观变化,同时建立了非线性模型.结果表明:建立的非线性模型可以很好地模拟沥青的老化速率和最终老化程度;随老化时间的增加,沥青中大粒径分子、中粒径分子和羰基含量变大,小粒径分子和丁二烯基含量变小;沥青混合料SMA-13的抗老化性能较SUP-13和AC-13更佳.     

Performance evaluation of a high durability asphalt binder and a high durability asphalt mixture for bridge deck pavements

This paper describes the results of laboratory and full-scale performance tests for a high durability asphalt binder (HDAB) and high durability asphalt mixture (HDAM) applicable to the wearing course in a bridge deck system. The HDAB was developed using a styrene–butadiene–styrene (SBS) modifier and hydrocarbon for improving construction workability and resistance to fatigue cracking. Various binder tests were conducted on the HDAB, and test results showed that the resistance to fatigue and low temperature cracking of the HDAB increased significantly compared to that of the PG 64-22 and PG 76-22 binders. For the mixtures, the fatigue test results showed that the HDAM has a three times longer fatigue life than the SBS-modified asphalt mixture. It was also found that the HDAM has a higher resistance against moisture-induced damage. Results from full-scale accelerated testing on the bridge deck pavement system proved that the HDAM can significantly improve pavement performance.     

高黏改性沥青高温黏弹特性指标区分度分析

为得到能准确区分高黏改性沥青高温性能的评价指标,分别对3种高黏改性沥青(高黏改性剂掺量均为12%)及基质沥青进行滞后环、动态剪切流变(DSR)和软化点等试验,并采用沥青混合料车辙试验进行了验证,基于沥青混合料试验结果对3种高黏改性沥青的高温性能评价指标作了一致性和区分度分析.结果表明:3种高黏改性剂的掺入均可提高基质沥青的黏弹特性和高温性能,但改性效果不同;不同高温评价指标基本能对3种高黏改性沥青的高温性能做出一致性评价,但区分能力不同,其中滞后环试验技术指标和Carreau模型拟合的零剪切黏度(ZSV)值区分度和评价效果最好,而车辙因子和软化点较差.     

Effects of rejuvenator on performance-based properties of rejuvenated asphalt binder and mixtures

Firstly, the performance-based properties of rejuvenated aged asphalt binders, i.e., the blends of aged binders containing a rejuvenator at various percentages, were investigated under high, intermediate and low temperatures. The tests were conducted on the blends at three stages as follows: no aging, rolling thin film oven (RTFO) residuals and as well RTFO + pressure aging vessel (PAV) residuals through dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. Optimum concentrations of the rejuvenator needed for the blends to reach a target PG grade were obtained from the blending charts of the rejuvenated aged binders in terms of performance properties. The rejuvenator is a soft binder containing a low asphaltene content of 2 wt%. Secondly, selected performance-based properties were conducted on hot mix asphalt (HMA) using the rejuvenated aged binder and a virgin HMA as a control mixture. Results showed that the rejuvenator affected significantly the performance-based properties of both the rejuvenated aged binders and the mixtures containing the rejuvenated aged binders. It was possible to get optimum concentrations of the rejuvenator using the blending charts so that the rejuvenated binders reach a target PG grade. The mean value of the concentrations was proved to be more reliable through the performance-based properties of the mixtures if it is used for a design value for recycling. The properties of the asphalt paving mixtures with the rejuvenated binders were even improved or in the same level as the properties of the virgin mixtures.     

Evaluating permanent deformation in asphalt rubber mixtures

Permanent deformation or rutting, one of the most important distresses in flexible pavements, has long been a problem in asphalt mixtures, mainly in countries with high temperatures such as Brazil. Throughout the years, researchers have used different test methods to estimate the rutting performance of asphalt mixtures. One of the alternatives to reduce permanent deformation in asphalt pavement layers is through the use of mixtures produced with asphalt rubber. Crumb rubber from waste tires introduced into the asphalt is one of suitable application to dispose the tires and used as an additive to enhance the properties of the conventional asphalts. This work aims at comparing the rutting performance of asphalt rubber mixtures (with dense and gap-graded aggregate gradation) with the conventional dense graded mixture most used in Brazil. The asphalt rubber mixtures were produced by the wet process using continuous blend and terminal blend asphalt rubber. To study their performance, two laboratory tests, the Repeated Simple Shear Test at Constant Height (RSST-CH) and the Accelerated Pavement Testing Simulator Test (wheel tracking) were carried out. The testing results confirmed that the use of asphalt rubber binder improves significantly the resistance to rutting. The highest resistance is presented by the mixtures produced with continuous blend binders and gap-graded aggregate gradation. The results of both testing apparatus can be correlated by a linear relationship. The testing results allowed concluding that the characteristics of the asphalt rubber binders cannot be used to predict the permanent deformation resistance of the asphalt rubber mixtures.