Microscopic and Dynamic Rheological Characteristics of Crumb Rubber Modified Asphalt

A test for crumb rubber modified asphalt containing 20% crumb rubber particles（30 mesh） was performed using a scanning electron microscope（SEM）.The experimental results indicate that the crumb rubber particles are evenly distributed in the asphalt.Shear rate sweep and shear-temperature sweep tests on the crumb rubber modified asphalt at-20-80 ℃ using a dynamic shear rheology（DSR） instrument,were carried out.The tests show that the complex modulus decreases with increasing temperature;at equivalent temperature,higher load frequencies lead to a larger complex modulus,and this value increasingly decreases as the temperature increases;the phase angle increases with temperature and decreases as the load frequency increases.It can be concluded that the rutting resistance limiting temperature of crumb rubber modified asphalt is 78 ℃,and the anti-fatigue limiting temperature is 16 ℃,which shows that the asphalt has preferable rutting resistance characteristics at high temperature,as well as anti-fatigue characteristics.In addition,the complex modulus master curve at different temperatures was plotted according to the time temperature equivalence principle,which allows the study of the dynamic state behavior of crumb rubber modified asphalt at a wide range of load frequency.

Creep Characteristics of Crumb Rubber Modified Asphalt Binder

Crumb rubber modified asphalt containing 20 percent crumb rubber particles of 30 mesh has been examined by Scanning Electron Microscope （SEM） to observe the microcosmic appearance and the characteristic distribution of crumb rubber particles in asphalt. The SEM pictures reveal that the crumb rubber particles distribute evenly in the asphalt and they are compatible well with asphalt. The shear creep test of crumb rubber modified asphalt was carried out at -10 ℃ and 40 ℃ by Dynamic Shear Rheology （DSR）. The shearing deformation at different temperature and creep stiffness modulus curve at loading stage of crumb rubber modified asphalt have been measured. The stiffness modulus of crumb rubber modified asphalt is much temperature sensitive and it decays much quick at the early stage of loading than normal asphalt. The rate of decay of stiffness modulus is slow at the subsequent stage and stiffness modulus approaches to a stable value at the final stage at a higher temperature. In addition, Burgers model is suitable to describe and simulate experimental results of viscoelastic properties of the crumb rubber modified asphalt.

Laboratory investigation on effects of organic montmorillonite on performance of crumb rubber modified asphalt

In this paper,organic montmorillonite(OMMT)was added into crumb rubber modified asphalt(CRMA)to improve its high temperature performance,anti-aging performance and storage stability.The effects of different OMMT content on properties of CRMA were studied.The rutting factor obtained by dynamic shear rheological(DSR)test was adopted to evaluate the high-temperature performance.The creep stiffness and m value determined by the bending beam rheometer(BBR)test were employed to evaluate the low-temperature performance.The softening point,ductility,rutting factor before and after rolling thin film ovens test(RTFOT)and pressure aging vessel test(PAV)were compared to characterize the aging properties.Moreover,the segregation test after being reserved for 48 h and 7 d was conducted,and the softening point and rutting factor of upper and lower layers of segregation pipe were adopted to evaluate the storage stability.The results indicated that the high-temperature performance and anti-aging performance were developed with the increasing content of OMMT,while the low-temperature performance deteriorated.The storage stability was improved with the increasing content of OMMT before the content exceeded 4%,after which the storage stability declined.Taking account of all factors,it is suggested that the optimum content of OMMT is 3%−4%.

Terminal Blend(TB)胶粉/SBS复合改性沥青性能研究

采用Terminal Blend(TB)技术制备了基质沥青牌号和SBS含量不同的6种TB复合改性沥青,并对它们的常规指标、感温性能、黏温特性和力学性能进行了评价。结果表明:TB复合改性沥青各项性能均显著优于基质沥青。TB复合改性沥青的性能与SBS含量和基质沥青的牌号有关。除温度敏感性外,其他各项性能均随SBS含量增加而得到改善。中油AH-70有助于改善软化点、针入度、针入度指数PI值、弹性恢复、峰值拉力Fmax、屈服应变能E、黏韧性面积S和黏韧性指标,中海AH-90则有助于改善延度、黏温曲线方程斜率、拉伸柔量f。

Laboratory and Field Investigations of Polymer and Crumb Rubber Modified Bitumen

In this paper, properties of new kind of modified bitumen are presented. Bituminous binder was modified with mix modification using polymer and additive of crumb rubber. Terminal blend process at the refinery was applied to produce the mixed modified binder. Laboratory tests were focused on the characterization of the properties of 45/80-55 CR binder with comparison to reference 50/70 and conventional polymer modified 45/80-55 bitumen. Based on conventional binder tests such as penetration, softening point and Fraass breaking point as well as BBR （bending beam rheometer） and DSR （dynamic shear rheometer） tests, rheological properties were investigated. For determination of stability of the polymer and crumb rubber, modified bitumen tube testing method was used. Based on the results analysis, improvement of the viscoelastic properties of polymer and crumb rubber modified bitumen was observed. Conventional properties and stability tests showed that it is possible to pass standard requirements for polymer modified bitumen. Mixed modification and terminal blend allow to use crumb rubber as a modifier with elimination of the separation of crumb rubber during transportation and storage at high temperature. In this paper, experience from filed sections with use of the asphalt mixture with new kind of modified bitumen is presented.

Performance Characterization of CR/PU Asphalt for Potential Application in Assembled Fast-Repairing Engineering

Conventional repairing methods for asphalt pavement have some inconveniences,such as insufficient strength,and are typically time-consuming.To address these issues,this study proposes a new technological method to design and prepare a high-performance assembled asphalt concrete block for fast repair of the potholes.A series of composite modified asphalt binders with 10%crumb rubber(CR)and different dosages(0%,1%,3%,5%)of polyurethane(PU)are examined to determine the optimized binder.Subsequently,the corresponding asphalt mixtures are prepared for further comparison and assessment of engineering properties,such as moistureinduced damage,high-temperature deformation,and low-temperature cracking characteristics.The test results show that PU can significantly improve the high-temperature performance and hardness of(crumb rubber modified asphalt)CRMA binder;3%PU contributes allowing the resistance of CRMA mixture to moisture-induced damage at higher levels,particularly under water whole immersion;as 3%PU is added,the high-temperature rutting deformation resistance of the CRMA mixture increases significantly,and the low-temperature anti-cracking properties are also improved slightly.Therefore,the innovatively designed high-quality assembled fast-repairing asphalt concrete block is recommended as an appropriate option for highway maintenance.

不同形貌纳米材料对Terminal Blend沥青性能及微观结构的影响

本研究选用纳米氧化硅和蒙脱土,制备了纳米-Terminal Blend(TB)改性沥青,测定了其针入度、软化点、延度、弹性恢复率等指标,得到了不同改性沥青的荧光显微照片(FM)和扫描电镜照片(SEM),还对样品进行了红外光谱分析。研究结果表明:两种纳米材料均使TB沥青针入度减小,软化点升高,高温性能得到改善,且纳米掺量越大,改善效果越明显。此外,层状纳米蒙脱土对TB沥青高温性能、弹性恢复改善效果优于纳米氧化硅,但对低温延度的改善不及后者。显微图像分析表明纳米氧化硅在改性过程中分散较好,而蒙脱土存在一定团聚现象。红外光谱分析显示纳米氧化硅改性TB沥青体系在指纹区个别峰消失,纳米蒙脱土改性TB沥青则在1602cm^(-1)处峰消失,同时在1107cm^(-1)、466cm^(-1)处出现新的吸收峰,引入纳米材料可能改变TB沥青的特征官能团。

TerminalBlend废胶粉-纳米SiO_2改性沥青粘温关系及低温韧性

为评价废胶粉-纳米复合改性沥青的高温抗变形性、流变特性及低温韧性,制备了湿法Terminal Blend胶粉-纳米SiO_2复合改性沥青,并借助旋转粘度、针入度、软化点、5℃和15℃延度试验进行了性能表征,还基于实测表观粘度拟合了复合改性沥青粘度-温度关系。结果表明:掺加纳米SiO_2后,复合改性沥青针入度减小,软化点升高,高温抗变形性能得到改善,且纳米SiO_2掺量越大,改善越显著;纳米SiO_2掺量4%时5℃延度比未掺前提高约37.5%。此外,复合改性沥青高温粘度较基质沥青和未纳米改性时有所增加,但135℃粘度不超过1500cP,施工和易性良好;粘度数据拟合还表明在135~200℃温度域内,复合改性沥青粘温关系符合较好的指数关系。

Terminal Blend胶粉改性沥青的发展

TB胶粉改性沥青是在传统湿法橡胶沥青的基础上,发展起来的一种新型改性沥青,具有黏度低、储存稳定性好等优点。从制备过程、改性机理、组分分析、性能评价、影响因素、应用及优缺点等方面,归纳总结了近年来TB胶粉改性沥青的相关研究成果,对TB胶粉改性沥青进行了全面的综述。重点介绍了TB胶粉沥青的改性机理,即胶粉在高温高速剪切条件下,发生脱硫降解反应,显著降低了结合料的黏度,改善了施工和易性、储存稳定性及低温性能,同时降低了高温性能。最新研究表明,采用TB+SBS、TB+纳米材料、TB+岩沥青或TB+反应型改性剂复合改性,能够制得综合性能较好的改性沥青,是TB橡胶沥青未来主要的发展方向。

Terminal Blend胶粉纳米改性沥青的动态剪切模量和黏度特性

为评价Terminal Blend胶粉纳米改性沥青的动态剪切流变特性,借助频率扫描试验测定了Terminal Blend胶粉纳米改性沥青60℃贮能模量、损耗模量、相位角及动态黏度随频率变化曲线,评价了纳米材料对流变特性的影响。研究结果表明:掺加纳米材料1(一种预先分散于聚合物基体的碳纳米材料)可显著增大低频域(ω≤10 rad/s)的贮能模量、降低相位角,有助于改善沥青弹性,但对损耗模量作用有限。在高频域(ω>10 rad/s),纳米改性剂对模量及相位角影响不明显。黏度数据表明,胶粉纳米改性沥青的动态黏度随加载频率增加而降低,表现出动态剪切稀化效应;纳米材料1能显著增加Terminal Blend沥青60℃动态黏度,有助于提高混合料抗车辙能力。数据拟合发现:利用Carreau模型表征胶粉纳米改性沥青的假塑性行为是可行的,且掺加纳米材料1后,零剪切粘度大于其他两组沥青。

多聚磷酸复配Terminal blend胶粉改性沥青流变特性及其混合料路用性能

基于针入度评价体系和PG分级体系研究了多聚磷酸(PPA)与Terminal Blending胶粉复合沥青性能,优化了最佳的PPA与TB胶粉掺量范围,采用车辙、低温弯曲、浸水马歇尔、冻融劈裂试验和四分点加载疲劳试验研究了PPA与TB胶粉复合改性沥青混合料的路用性能、抗疲劳性能和自愈合性能,并将其与4.5%SBS改性沥青混合料进行了对比。结果表明,TB胶粉改性沥青低温性能和抗疲劳性能优良,但其高温性能较差,将TB胶粉与PPA复配后可实现二者对沥青混合料高低温性能和抗疲劳性能改善效果的优势互补。在1.0%~1.5%PPA掺量和18%~24%TB胶粉掺量范围内TB与PPA复合改性沥青可替代4.5%SBS改性沥青,且PPA与TB胶粉复合改性沥青混合料具有更优的路用性能和抗疲劳性能。1.0%PPA+18%TB、1.25%PPA+22%TB、1.5%PPA+26%TB三种复合改性沥青混合料疲劳寿命比4.5%SBS改性沥青混合料高40%~110%,室温放置4个月后的自愈合性能为SBS改性沥青混合料的2.5倍,掺TB胶粉改性沥青显著提高了PPA改性沥青混合料的抗疲劳耐久性和自愈合性能。推荐PPA与TB胶粉复合改性沥青中,适宜的PPA掺量为1.0%~1.5%,TB胶粉合理掺量为20%~24%。

Terminal Blend胶粉与SBS复合改性沥青的路用性能

依托河北石家庄某沥青路面试验段,对Terminal Blend胶粉和SBS复合改性沥青混合料的高温性能、低温性能、疲劳性能进行了研究。试验结果表明,复合改性沥青混合料与SBS改性沥青混合料相比,具有突出的疲劳性能,疲劳寿命为SBS改性沥青混合料的1.5~4.5倍;复合改性沥青混合料的高温抗车辙性能、水稳定性与SBS改性沥青混合料相当,抗水损害性能则略好于SBS改性沥青混合料。

Terminal Blend胶粉改性沥青研究进展

近年来国内外的科研人员对橡胶粉改性沥青(AR)的研究比较深入,但是AR因为黏度太大导致其和易性较差,因此性能更优的Terminal Blend(TB)胶粉改性沥青受到了广泛关注。从TB胶粉改性沥青的制备工艺,性能影响因素和质量改善措施对TB改性沥青的国内外研究进展进行概括总结,旨在结合国外相关经验和技术,推动我国对TB胶粉改性沥青的研究。

硫化橡胶沥青和脱硫橡胶沥青的性能评估

文中采用扫描电子显微镜(SEM)观察了硫化橡胶粉和脱硫橡胶粉的微观形貌.以硫化橡胶粉和脱硫橡胶粉作为改性剂制备了改性沥青,并以基质沥青作为对照组,评估了三种沥青的高温性能和低温抗裂性能.通过红外光谱分析了其改性机理.结果表明:硫化胶粉颗粒表面光滑,棱角明显,颗粒相对分散.脱硫胶粉颗粒表面粗糙,颗粒有团聚现象.硫化胶粉改性沥青的粘度最大,脱硫胶粉改性沥青粘度次之,基质沥青的粘度最小.胶粉脱硫可以降低沥青的温度敏感度.硫化胶粉的高温抗车辙性能和低温抗裂性能均优于脱硫胶粉改性沥青.硫化胶粉改性沥青和脱硫胶粉改性沥青其主要以物理混溶为主.

TB胶粉改性沥青制备方法比较研究

高温法Terminal Blend(TB)胶粉改性沥青技术同时解决了传统橡胶沥青黏度大、存储稳定性差、恶臭排放的问题,但260℃高温工艺可能会引起安全问题,且生产难度较高。采用红外光谱分析(FTIR)、溶解度试验、凝胶渗透色谱分析(GPC)、流变学试验、存储稳定性试验,综合对比了高温法(260℃)、化学活化法(200℃)、高速剪切法(200℃)制备胶粉改性沥青的分子结构、溶解度、分子量分布、流变性质、离析等指标。结果表明:3种方法制备的胶粉改性沥青,均发生了脱硫反应(红外光谱966 cm^(-1)峰活性聚合物基团增强)与降解反应(部分胶粉大分子链段降解,产生与沥青质尺寸相当的分子链),高温法和化学活化法的脱硫降解程度比剪切法剧烈;高温法和化学活化法制备TB胶粉改性沥青的溶解度不低于96%,较剪切法提高4%~7%,135℃黏度约为1.2~1.3 Pa·s,约为剪切法的1/3;20%胶粉含量下,200℃高速剪切法及48 h发育难以制备出低黏度TB胶粉改性沥青;降低胶粉含量可在发育过程中加快胶粉的降解,高速剪切法具有制备低含量TB胶粉改性沥青的潜力。

SBS/胶粉复合改性沥青共混改善及其性能提升技术

为提高SBS/胶粉复合改性沥青的储存稳定性,对其共混工艺进行了改善。分别采用不同掺量的胶粉和SBS对基质沥青进行改性,得到胶粉改性沥青母液和SBS改性沥青母液,通过将这2种母液混合制备得到共混SBS/胶粉复合改性沥青,通过与传统SBS/胶粉复合改性沥青进行对比,研究了共混改善工艺对其物理性能、流变性能和疲劳性能的影响。结果表明:共混改善工艺显著提升了SBS/胶粉复合改性沥青的综合性能,当共混时间为30 min时,提升效果最佳;当胶粉掺量为20%时,共混SBS/胶粉复合改性沥青的储存稳定性提升约30%、低温松弛性能提升约14.6%、疲劳寿命提升约23.7%,而高温蠕变性能几乎不变;综合共混SBS/胶粉复合改性沥青的软化点变化趋势,在30 min的共混时间下,胶粉的最优掺量为20%。

轻度解交联橡胶粉干法改性SMA13性能研究

通过沥青混合料车辙试验、小梁弯曲试验、冻融劈裂及浸水马歇尔试验,研究了不同掺量轻度解交联橡胶粉(LDCR)对干法改性SMA13高温性能、低温性能与水稳定性的影响。结果表明,掺入LDCR提高了SMA13的高温性能,尤其当掺量≥2%时,混合料的动稳定度超过4.5%SBS改性SMA13(对照组);2%掺量的LDCR干法改性SMA13低温抗裂性最优;总体上LDCR干法改性SMA13的水稳定性低于对照组。综合考虑,LDCR的最佳掺量为2%,与对照组相比,可降低材料成本约5%。

废胎胶粉和天然胶乳改性沥青的老化和流变性能研究

【目的】研究废胎胶粉和天然胶乳改性沥青的耐老化和流变性能。【方法】利用天然橡胶(Natural Rubber,NR)胶乳和废胎胶粉(Crumb Rubber,CR)制备橡胶沥青,通过针入度、软化点、延度和动态剪切流变试验,对比分析基质沥青和橡胶改性沥青老化前后常规性能和流变性能。【结果】结果表明,CR和NR胶乳的加入降低了橡胶沥青的针入度等级,提高了橡胶沥青的软化点和延度。与常规沥青相比,CR掺量高达8%,NR胶乳掺量高达4%时,橡胶沥青的复数模量和抗车辙性能均得到了显著提高。【结论】CR和NR胶乳的加入可提高改性沥青的总体性能,改善沥青路面的耐久性。

废旧胶粉/SBS复合改性沥青高温抗车辙性能研究

为提升沥青结合料的高温抗车辙性能,本研究使用CR和SBS两种聚合物对基质沥青进行复合改性。首先,基于常规的沥青性能试验(针入度、软化点和延度试验),对不同掺量下的CR和SBS单一聚合物改性沥青进行高-低温性能研究;继而,利用常规性能试验研究CR掺量对废旧胶粉/SBS复合改性沥青性能的影响,其中SBS掺量固定为2%,仅改变复合改性沥青中CR的掺量;最后,基于动态流动剪切仪(Dynamic Shear Rheometer,DSR)对废旧胶粉/SBS复合改性沥青进行多应力蠕变松弛(Multiple Stress Creep and Recovery,MSCR)试验,利用不可恢复蠕变柔量(Jnr)和应变恢复率(R)两个指标进一步研究废旧胶粉/SBS复合改性沥青高温抗车辙性能。结果表明,2%SBS和12%CR复合改性沥青的抗车辙性能优异,甚至优于SBS掺量为4.5%的SBS改性沥青。

胶粉复合改性沥青的研制及工业化生产

以某公司加工的环烷基和中间基原油为原料,通过优化原油配比,采用常减压蒸馏工艺,通过控制减压蒸馏工艺条件,生产出符合技术标准要求且能够用于改性沥青的基质沥青原料。通过筛选与基质沥青配伍性好的胶粉、助剂添加比例及工艺条件优化,研制出符合技术规范要求的胶粉复合改性沥青并进行了工业试生产。对工业生产的产品检测及专业部门鉴定结果表明,胶粉复合改性沥青产品各项技术指标符合JT/T798-2019《路用废胎胶粉橡胶沥青》技术要求,成功实现了工业化生产和应用。