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.

Ageing and performance of warm mix asphalt pavements

This paper presents results from investigating the ageing behaviour and performance of different warm mix asphalt （WMA） pavement mixtures also called energy reduced pavements. The mixtures were either prepared in the laboratory or taken directly from a mixing plant. The study compared the rutting and fatigue behaviours of unaged material in comparison to long term laboratory aged material. In order to conduct the long term ageing, a special laboratory ageing protocol with different heating, cooling and watering cycles had been developed. The investigation revealed a quite controversial rutting behavior which could not be explained with the available data. While most aged energy reduced pavements showed increased rutting for other mixtures, lower rut depths could be found. As opposed to this finding, fatigue and stiffness of all aged energy reduced pave- ment samples compared to unaged samples improved significantly. The overall results led to the conclusion that the ageing of energy reduced pavement simulated in the laboratory is not very critical regarding their mechanical performance. Therefore, it was confrmed that the application of this type of pavement provides a good solution for saving on CO2 emissions. Another advantage is that by using energy reduced pavements the road con- struction season can be significantly prolonged.

Testing and assessing the performance of a new warm mix asphalt with SMC

Warm mix asphalt （WMA} is a new technology which asphalt mix is produced and placed at normal temperature. It has advantages including low cost, environmentally friendly, haul-convenience, and so on. WMA has been widely tested and applied in the USA in the last decade, but it has just started in China. Recently, a new WMA using a new plastic- macromolecule-normal temperature additive, which was called ＂SMC＂ by the production company, was introduced as asphalt modifier. Based on discussing the strength forming process of this new WMA with SMC, a series of laboratory tests, including Marshall stability test （MST）, boiling test （BT）, modified immersion Marshall test （MIMT）, freeze-thaw split- ring test （FTST）, rutting test （RT）, low-temperature bending test （LTBT）, and abrasion loss test （ALT）, were conducted in this study to assess the performance of this WMA and the capability of applying it on low volume roads in China. SMC modified asphalt mixed under normal temperature is used in testing samples. It was found that this WMA product exhibited merits on its strength, which was about 6.7 kN bigger than the requirement of 5.0 kN in the JTG F40-2004, on high-temperature stability, which is about 1100 times/ram greater than the requirement of 600-1000 times/mm in the ）TG F40-2004, and on its storage stability. Based on these indicators, it is recommended that this product could be used for low volume low class roads construction. However, due to the relatively lower water resistance and low-temperature cracking resistance, this product is suggested to be applied first in the areas with warm weather and little rainfall. In order to improve the perfor- mance of this WMA with SMC, further research on this SMC asphalt modifier should be continued.

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.

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.

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.

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。

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。

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。

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。

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.

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。

不同制备工艺的温拌橡胶沥青性能

为了研究不同制备工艺的温拌橡胶沥青性能差异,分析温拌橡胶最佳的制备工艺,分别制备了3种不同制备工艺的温拌橡胶沥青,包括:先制备橡胶沥青,再与温拌剂混合;先混合温拌剂与橡胶颗粒,再制备温拌橡胶沥青;制备橡胶沥青过程中加入温拌剂。通过开展不同制备工艺的温拌橡胶沥青针入度试验、软化点试验、流变试验与红外光谱试验,分析不同制备工艺的温拌橡胶沥青针入度、软化点、车辙因子、相位角、疲劳因子、劲度模量与化学组成的指标差异,研究温拌剂以及不同制备工艺对橡胶沥青性能的影响。同时,采用不同制备工艺的温拌橡胶沥青进行沥青混合料试件成型,研究适宜的击实温度及路用性能,包括高温稳定性、低温抗裂性与水稳定性。结果表明:温拌剂的掺入将导致橡胶沥青针入度增大,软化点减小,抗车辙性能下降,但不会对橡胶沥青的低温抗裂性与抗疲劳性能产生影响;温拌剂可有效降低混合料的击实温度,不会对橡胶沥青混合料的低温抗裂性与水稳定性产生影响,但其将导致混合料的抗车辙性能下降;提前混合温拌剂与橡胶颗粒的制备工艺可以增加橡胶颗粒与沥青的溶合效应,将温拌剂对橡胶沥青抗车辙性能的影响减少到最低,同时可以降低橡胶沥青与橡胶沥青混合料的生产温度,在3种不同制备工艺中具有明显的优势。

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。

全比例温拌再生沥青混合料的路用性能

废旧沥青混合料的回收再利用是推动节能减排的重要举措。针对RAP(废旧沥青混合料)利用率较低等问题,提出全比例温拌再生沥青混合料的技术方案,实现100%RAP利用率,同时以马歇尔试验确定最佳外掺剂用量。将全比例温拌再生沥青混合料与常规热拌沥青混合料进行性能比对。结果表明:再生AC-13C沥青混合料的60、70℃车辙动稳定度分别为6364、3158次/mm,低温弯曲破坏应变为2834με,其水稳定性等路用性能测试指标也满足现行规范的技术要求。

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。