Warm asphalt rubber:A sustainable way for waste tire rubber recycling

Recycling end-of-life tire rubber as asphalt modifier is known as a sustainable paving technology with merits including enhanced pavement durability,waste tire consumption and noise reduction.However,the criticisms on the high construction emissions of asphalt rubber(AR)have limited its application.Warm mix asphalt(WMA)effectively reduces the mixing and compaction temperatures of conventional hot mix asphalt mixtures.The combination of AR and WMA,called warm asphalt rubber(WAR),is a promising paving material which achieves pavement sustainability from principles to practices.Many studies have demonstrated that WMA technologies work effectively with AR pavement in different ways,alleviating the concerns of potential higher emissions of AR by decreasing mixing and paving temperatures.A comprehensive literature review about WAR brings a better understanding of this promising paving technology.The findings of 165 publications were summarized in this review.It summarized the recent developments of WAR in various aspects,including rheological properties,mix design,mixture mechanical performance,field application,construction emission,and asphalt-rubber-WMA additive interaction.It is expected that this review is able to provide extensive information to explore further research development and application of WAR.

Construction Technology of Warm Mix Asphalt Pavement in Cold High-Altitude Areas

With the continuous development of domestic highway construction,highway civil engineering and service level quality have attracted much attention.Good pavement quality and high-quality service make people feel comfortable and smooth when traveling.High-quality pavement can significantly reduce the probability of traffic accidents.At present,there is a direct relationship between pavement quality and pavement construction operations.Carrying out pavement construction operations in cold high-altitude areas requires a reasonable selection of construction equipment and methods.The application of warm-mix asphalt pavement construction technology can ensure pavement quality.Therefore,this paper analyzes the advantages of warm-mix technology,the environmental characteristics of cold high-altitude areas,and construction preparations,and discusses the construction technology of warm-mix asphalt pavement in cold high-altitude areas in detail,to improve the overall road quality of cold high-altitude areas.

Rheological properties of warm mix asphalt binder by DSR test at medium temperature

The rheological properties including the complex modulus G＊ and the phase angle δof matrix and warm mix asphalt （WMA）binders were measured by using the dynamic shear rheometer （DSR ） test at the medium temperature ranging from 16 to 40 ℃,and the relationships between the fatigue factor G＊ sinδand the matrix binder property,WMA additive and test temperature were established.It is found that G＊ decreases with the increasing temperature while δincreases inversely,and G＊ of the asphalt binder with high WMA additive dosage is large,and δis small.G＊sinδexponentially decreases with the increasing temperature and linearly increases with the increase in additive dosage,and the amplitudes of variation are large at low temperatures and high additive dosages.The effect of WMA additive on the rheological property is more remarkable for the matrix asphalt binder with low G＊.Besides,aging has a great effect on the property of matrix asphalt binder,and a slight effect on the interaction between asphalt and additive.The high additive dosage can increase the fatigue cracking potential of the asphalt binder.

Long term performance of warm mix asphalt versus hot mix asphalt

The fatigue behavior, indirect tensile strength （ITS） and resilient modulus test results for warm mix asphalt （WMA） as well as hot mix asphalt （HMA） at different ageing levels were evaluated. Laboratory-prepared samples were aged artificially in the oven to simulate short-term and long term ageing in accordance with AASHTO R30 and then compared with unaged specimens. Beam fatigue testing was performed using beam specimens at 25 ℃ based on AASHTO T321 standard. Fatigue life, bending stiffness and dissipated energy for both unaged and aged mixtures were calculated using four-point beam fatigue test results. Three-point bending tests were performed using semi-circular bend （SCB） specimens at -10 ℃ and the critical mode I stress intensity factor K1 was then calculated using the peak load obtained from the load-displacement curve. It is observed that Sasobit and Rheofalt warm mix asphalt additives have a significant effect on indirect tensile strength, resilient modulus, fatigue behavior and stress intensity factor of aged and unaged mixtures.

Warm-Mix Asphalt and Pavement Sustainability: A Review

Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the development and deployment of warm-mix asphalt technologies. Such technologies make it possible to produce and place asphalt concrete at reduced temperatures compared to conventional hot-mix methods. Several studies have reported on the potential of warm-mix asphalt with regard to improved pavement performance, efficiency and environmental stewardship. This paper reviews several of those studies in the context of pavement sustainability. Overall, warm-mix asphalt provides substantial sustainability benefits similar to or, in some cases, better than conventional hot-mix asphalt. Sustainability benefits include lower energy use, reduced emissions, and potential for increased reclaimed asphalt pavement usage. Growth in utilization of warm-mix asphalt worldwide may, in the not-too-distant future, make the material the standard for asphalt paving. Regardless, there are concerns over some aspects of warm-mix asphalt such as lower resistance to fatigue cracking, rutting and potential water-susceptibility problems, particularly with mixes prepared with water-based technologies, which require further research to address.

温拌SBS改性再生沥青混合料的路用性能研究

为研究再生SBS改性沥青混合料(RAP)掺量和温拌剂种类对温拌SBS改性再生沥青混合料的路用性能的影响,通过车辙试验、小梁弯曲试验和冻融劈裂试验分析了在RAP掺量为0,10%,30%,50%,Sasobit温拌剂掺量为3.0%和Evotherm温拌剂掺量为2.0%的温拌SBS改性再生沥青混合料的高温稳定性能、低温抗裂性能和水稳性能,并通过灰色关联度分析RAP掺量对两种温拌再生沥青混合料路用性能的影响。结果表明,RAP的掺入可以极大地改善温拌再生沥青混合料的高温性能,但不利于其低温抗裂性能和水稳定性能。不同RAP掺量的沥青混合料对各项路用性能影响程度大小排序均为:水稳定性能<低温抗裂性能<高温稳定性能。在RAP掺量为30%时,掺入Evotherm温拌剂的再生沥青混合料的高温性能、低温抗裂性能、水稳定性能优于掺入Sasobit温拌剂的再生沥青混合料。

沥青温拌技术分类及温拌效果的试验评价方法

沥青温拌技术日益广泛应用于路面工程,为了定量评价温拌沥青混合料在拌和生产过程中的温拌效果,提供试验评价方法,本研究自主开发了一种沥青混合料变速拌和试验装置,采用70^(#)基质和SBS改性两种沥青、自主研发的一种表面活性剂型沥青温拌剂(取名为Alube)和一种有机降黏型沥青温拌剂(取名为ACMP),以市场成熟产品Evotherm为参照,分别制备了温拌沥青及其AC-13C型混合料,测试了不同沥青和温拌沥青的三大指标、布氏黏度和动态剪切流变指标,分析了沥青的黏温曲线特性,通过混合料的变温击实试验和变速拌和试验,研究了沥青混合料的压实特性和拌和流动特性,提出了沥青混合料的拌和流动模型。研究结果表明,有机降黏型温拌剂减小了沥青的黏度,增大了沥青的流动性,改变了沥青的技术性能,如针入度、延度、相位角等增大,软化点、布氏黏度等减小,而表面活性剂型温拌剂不改变沥青的基本技术性能;黏温曲线法仅可表征有机降黏型温拌沥青的温度变化,等黏温度降低约9℃,变温击实法和变速拌和法则可以同时表征两大类温拌剂的温拌效果;沥青混合料的拌和流动性服从宾汉黏塑性模型,从流变理论上解答了混合料的拌和流动性及和易性,推荐采用变速拌和试验来评价温拌沥青混合料的温拌效果;综合考察现有沥青温拌技术可知,在常用温拌剂掺量下,温拌沥青的生产拌和温度可比热拌沥青混合料低20~30℃,符合常规认识。

聚乙烯蜡温拌再生沥青性能研究

聚乙烯蜡可提升沥青路用性能,同时具有良好的经济效益而受到研究人员的广泛关注。选取新聚乙烯蜡(NPEW)与回收聚乙烯蜡(RPEW)按照等比混掺的方式作为温拌剂(PEW),将PEW与再生剂(LBS)加入新旧共混沥青中制备了聚乙烯蜡温拌再生沥青,其中新旧共混沥青中分别含20%、30%、40%的老化SBS改性沥青(AAM),用于模拟实际路面再生过程中旧沥青比例。通过沥青三大指标、布氏黏度对不同PEW及AAM掺量下温拌再生沥青的感温性能、高低温性能及降黏效果进行分析。结果表明,AAM和PEW的添加可减少温拌再生沥青的温度敏感性;当温拌再生沥青中AAM掺量一定时,随着PEW掺量的增加,高温抗变形能力,低温抗裂性能均有显著提升;当温拌再生沥青中AAM掺量较低时,PEW的掺入可有效降低黏度;当AAM掺量30%,PEW掺量2%时,温拌再生沥青兼具最佳的路用性能及经济效益。

温拌再生沥青砂浆二次老化前后抗反射开裂性能评价

为研究温拌再生沥青路面的抗反射开裂性能,结合Overlay Tester(OT)试验与数字图像相关(Digital Image Correlation,DIC)技术,研究了长期老化后废旧沥青混合料(Reclaimed Asphalt Pavement,RAP)掺量对温拌再生沥青砂浆抗反射开裂性能的影响。研究结果表明:经过二次老化后,RAP掺量对温拌再生沥青砂浆的抗反射开裂性能影响显著,二者成负相关关系;在相同的老化条件下,不同RAP掺量的再生沥青砂浆裂缝扩展规律基本一致,二次老化后再生沥青砂浆的反射裂缝在初期开裂速度加快。

EC130温拌剂对SBS改性沥青高温性能及抗疲劳性能的影响

作为制备沸石发泡沥青的发泡剂,EC130温拌剂释放的发泡水和残留的沸石矿物对沥青的性能有着不同的影响.为研究EC130温拌剂对SBS改性沥青高温性能和抗疲劳性能的影响,采用石灰岩矿粉、EC130沸石矿物和EC130温拌剂等3种添加物,设计了以添加物掺量为变量的单因素试验.以石灰岩矿粉为参照对象,通过温度扫描试验、多重应力蠕变恢复试验和线性振幅扫描试验,分析了EC130沸石矿物和EC130温拌剂释放的发泡水对SBS改性沥青高温性能和抗疲劳性能的影响.结果表明:同石灰岩矿粉一样,沸石发泡沥青中的EC130沸石矿物使沥青弹性增大、黏性减小,有利于抗车辙性能的提升,但不利于抗疲劳性能;沸石发泡沥青中的发泡水使其黏性增大、弹性减小,有利于抗疲劳性能的提升,但不利于抗车辙性能.

SMC再生SBS沥青的流变性能和微观特性研究

【目的】探究新型温拌再生剂甲基苯乙烯共聚物(styreneic methyl copolymer,SMC)对老化苯乙烯系热塑性弹性体(styrene butadiene styrene,SBS)改性沥青的再生效果和再生机理。【方法】首先,在室内制备不同老化程度的沥青。然后,采用SMC再生剂对不同老化程度的SBS改性沥青进行再生。接着,对再生后的SBS改性沥青进行动态剪切流变和低温弯曲蠕变试验,以评价其流变性能。最后,开展红外光谱试验以揭示其作用机理,进行电镜扫描试验以验证SMC再生剂的再生效果。【结果】SMC再生剂会降低老化SBS改性沥青的车辙因子,降低老化SBS改性沥青的恢复率,同时会使老化SBS改性沥青的低温性能得到极大提升。SMC再生剂未与SBS改性沥青发生化学反应,两者仅为物理共混。同时,SMC再生剂能够弥补沥青因老化产生的裂缝。【结论】SMC再生剂对老化SBS改性沥青具有较好的修复效果,能够为沥青的再生提供一种新的途径。

Performance evaluation and chemical property analysis of RWMA binders with 100% artificial reclaimed asphalt

The performance evaluation and chemical property analysis of the recycled warm mix asphalt （RWMA） binders containing 100% artificial reclaimed asphalt （ RA） are presented, and the combined effects of different percentages of the rejuvenator and warm mix additive （WMA） additives on RWMA binders are analyzed through laboratory tests. Three types of WMA additives ad one commercial rejuvenator named GST were selected to restore the artificial RA. The laboratory performace tests including the penetration test, softening test ad rotary, viscosity （RV） test were carried out. In addition, the Fourier transform infrared spectroscopy （FTIR） test was performed to explore the chemical property of RWMA binders. The results of the performance tests indicate that the rejuvenator GST has the ability to restore the artificial RA; choosing the optimum content of WMA additives and rejuvenator is the key to restoring 100% artificial RA, since the combined effects of them play an important role in determining the basic laboratory performance of RWMA binders. The FTIR tests show that the process of recycling mainly adjusts the chemical component of aged asphalt and no remarkable change is observed in the FTI1R spectra of RWMA binders in terms of chemical functional groups with the introduction of WMA additives.

表面活性泡沫沥青发泡工艺及流变特性研究

温拌沥青技术可降低沥青混合料生产和施工温度,在节能减碳方面极具应用潜力。泡沫温拌沥青技术成本较低,虽存在改性沥青发泡效果不理想、温拌效果不显著等问题,但具有潜在的推广应用前景。表面活性剂兼具“沥青润滑剂”和“泡沫稳定剂”的作用效能,为改善泡沫温拌沥青发泡特性和温拌效果提供了可能。基于此,本研究采用不同质量分数的表面活性剂水溶液,在不同发泡温度下制备了表面活性泡沫沥青(SAFB6,SAFB8,SAFB10),利用发泡试验、动态剪切流变试验以及弯曲梁流变试验测试了沥青的发泡特性、高温性能、抗疲劳性能和低温性能,并借助傅里叶红外光谱试验分析了作用机理,揭示了表面活性剂与发泡过程对泡沫温拌沥青性能的协同提升作用。试验结果表明:表面活性剂对SBS改性沥青的发泡特性有明显的协同作用,特别是半衰期,最大可达69 s;SAFB沥青最佳发泡条件为发泡温度170℃,表面活性剂含量8%;SAFB沥青制备过程中没有发生复杂的化学反应,但是发泡过程导致SBS改性沥青发生了一定程度的氧化作用;表面活性剂和发泡工艺的协同效应提高了SBS改性沥青的高温性能和抗疲劳性能,而低温抗裂性能与SBS改性沥青相当。总体而言,表面活性剂与发泡技术相结合是可行的,提高了SBS改性沥青的发泡效果和路用性能。

RAP掺量对温再生沥青混合料力学性能和路用性能的影响规律研究

温再生技术是一种有效的利用沥青混合料回收料(RAP)实现再生的新技术。为改善温再生沥青路面性能,有效提高RAP的循环利用率,通过力学性能和路用性能分析考察了RAP掺量对温再生沥青混合料性能的影响规律,探讨动稳定度与重复加载蠕变试验力学参数的相关性。研究结果表明:随着RAP掺量的增加,温再生沥青混合料的高温稳定性、抗剪切和抗弹性变形能力提高,但低温抗裂性能、水稳定性能有所下降。此外,流动数与动稳定度之间具有较好的线性相关性,可以借助流动数评价混合料的高温抗车辙能力;相同RAP掺量下,改性温再生沥青混合料的各项性能均优于普通温再生沥青混合料,当RAP掺量达70%时,混合料各项性能仍能满足规范要求,可为后期工程应用和质量控制提供依据。

废油/树脂/己二酸二辛酯复合再生剂制备及温拌剂对沥青拌合老化保护效果评价

为验证废油对老化沥青性能恢复的适用性,借助响应面法使用废油、C9石油树脂、己二酸二辛酯配制了一种复合废油再生剂。为避免再生沥青拌合过程中轻质组分的挥发及老化,研究引入温拌剂降低拌合温度进而实现对再生沥青的性能保护。同时,测定了再生剂对老化沥青的再生效果以及温拌剂的保护效应。研究发现,老化沥青低温延展性不良的缺陷得到恢复,再生沥青高温抗变形能力优于基质沥青;再生沥青经温拌后,黏性成分更多,进而低温流变表现占优。再生剂有效补充了老化沥青的芳香族化合物;温拌再生沥青小分子油分物质得到了保护,二次老化中大分子物质基团的生成得到了控制。

短期老化对温拌橡胶沥青路用性能的影响

为了研究短期老化对温拌橡胶沥青路用性能的影响,首先利用质量损失实验对其老化前后组成成分的质量变化进行初步的评估与分析;采用针入度、软化点、动态剪切流变实验对旋转薄膜烘箱短期老化前后橡胶沥青材料路用性能的差异性进行比较,同时借助凝胶渗透色谱对作用机制进行分析与验证。研究表明:虽然老化前后橡胶沥青的路用性能稍微减弱,但改性作用仍然在可接受范围内,且均比普通基质沥青高出很多;虽然液态降黏减阻剂本身平均分子质量较小,在短期老化过程中容易蒸发,但这种作用保护了基质沥青当中的轻质组分,有效地减缓了老化进程,温拌橡胶沥青较普通橡胶沥青和基质沥青具有更好的抗老化性能。

长大隧道沥青路面铺装中温拌阻燃技术对施工环境的影响

以长大隧道为研究对象,分别测试热拌工艺和温拌阻燃工艺条件下隧道中部挥发性有机化合物(VOC)体积分数、CO体积分数和照度在施工区域的变化情况,由此分析评价温拌阻燃工艺对长大隧道沥青路面施工环境的影响。结果表明:长大隧道铺装采用热拌工艺时,整个作业区域内的沥青烟质量浓度数值均偏高,且部分区域超出了阈值,照度均在人行照度标准之下;而采用温拌阻燃工艺时,施工区域沥青烟质量浓度降低显著,其中VOC体积分数降低26.8%,CO体积分数降低21.9%,施工区域照度提高103.2%,施工环境得到显著提升;良好的隧道铺装施工环境不仅有利于施工人员的身心健康,而且有助于提高隧道铺装施工质量。

Asphaltan A~温拌剂对橡胶沥青微观特性的影响研究

对基质沥青、橡胶沥青以及添加Asphahan A温拌橡胶沥青进行四组分试验和差热试验（DSC）分析，通过微观尺度研究温拌橡胶沥青的改性机理，试验结果表明，Asphahan A加入橡胶沥青之后，对橡胶沥青化学组分的影响主要体现在它使得橡胶沥青中饱和分含量的增加，沥青质含量的减少；由差热试验分析可知，Asphaltan A与橡胶沥青并没有发生复杂化学反应，它的加入引起了橡胶沥青中各组分吸热峰的改变，主要是对吸热峰的面积的改变，且与组分试验能相互对照。

生物和再生沥青及其混合料性能研究

通过设计再生生物沥青方案来探讨其在筑路材料应用中的可行性:首先采用生物沥青替代沥青,然后加入高比例的RA(>30%),最后在较低的温度(140℃)下生产沥青混合料,并系统评估了胶结料和混合料的性能。结果表明,温拌再生生物沥青混合料具有良好的承载力,50%和70%RA掺量的再生生物沥青的劲度模量分别为18120 MPa和15683 MPa,50%和70%RA掺量的再生生物沥青的永久变形百分比分别为0.5%和0.7%。70%RA掺量的再生生物沥青具有较好的水敏感性,其间接拉伸强度比为97%。本研究可为温拌再生生物沥青的研究提供参考。

BMH型温拌剂对废塑/SBS复合改性沥青疲劳性能的影响

借助动态剪切流变仪(DSR)温度扫描试验、时间扫描试验、线性振幅扫描试验以及红外试验对废塑/热塑性丁苯橡胶(SBS)复合改性沥青的抗疲劳性能进行了分析。结果显示:路陆邦(BMH)型温拌剂可以降低废塑/SBS改性沥青的疲劳因子,降低耗散能,提高抗疲劳性能,且以1.2%(质量分数,下同)的掺量表现最佳。归一化动态模量衰减至初始模量50%的指标值(N_(f50))和刚度比(S)×循环加载次数(N)均可以用来表征温拌废塑/SBS复合改性沥青的疲劳寿命,通过S×N指标来表征的疲劳寿命总体上低于N_(f50),1.2%掺量改善抗疲劳性能最优,1.4%掺量改善效果不升反降。BMH型温拌剂对于老化后沥青试样疲劳性能的改善效果更明显;无论是老化还是未老化的沥青试样,温拌剂的改善效果在高应变水平环境中更为突出;抗疲劳性能以1.2%掺量BMH型温拌剂样品最优。BMH型温拌剂能够通过降低羰基及亚砜基含量来提高沥青抗疲劳性能,对老化后的沥青提升效果更明显,这与线性振幅扫描试验结果一致。