废旧橡胶改性沥青的老化研究现状

废旧橡胶改性沥青可显著延长路面寿命。本文综述了国内外废旧橡胶改性沥青的热氧老化、紫外老化和水老化行为,使用宏观性能和微观结构变化分析了橡胶改性沥青老化特点。橡胶改性沥青在热、氧、紫外、水的作用下发生老化,软化点升高,针入度降低,羰基含量增加。特别是光、氧老化对经过水老化后的橡胶改性沥青老化作用尤为明显,水溶解了部分老化产物促进了沥青的老化。目前对于橡胶改性沥青老化过程中胶粉、沥青的结构性能变化和其环境耦合因素对橡胶改性沥青的老化研究及分析手段还很少,在今后的研究中须引起重视。     

煤基重质产物对滨州90#沥青的改性作用

对照优质道路沥青改性剂TLA,考察了六种煤基重质产物对滨州90#沥青的改性作用及作用原理。实验结果表明,六种改性剂对滨州90#沥青均表现出一定的改性作用。依据美国ASTM D5710-95以及英国BSI BS3690对TLA改性沥青的标准,六种改性沥青中,四种符合标准要求,其余两种不符合延度指标要求。FT-IR谱图分析表明,煤液化或煤油共处理重质产物的添加,没有生成新官能团,但使官能团的分布发生了变化,从而改善了基质沥青的路用性能,添加TLA,可增加C=O和S=O极性官能团,可增加沥青与石料的作用;煤焦油沥青过高的芳香结构,妨碍了其与基质沥青的混合作用。结合四组分分析结果,基于沥青胶体化学理论分析,发现不符合要求的改性沥青具有较高的饱和分含量,导致了较小的CI值(胶体指数),不利于沥青胶体结构的稳定。按线性加和法计算得到的改性沥青CI值与实测值的差距表明,改性过程包含有一定程度的化学反应。     

溶解涂膜红外光谱法测定改性沥青中苯乙烯-丁二烯-苯乙烯嵌段共聚物的含量

<正>改性沥青是指将细磨的橡胶粉、塑料粉等高分子聚合物或其他填料型外掺剂与沥青均匀混合,使沥青的性质得以改善而制成的沥青混合物[1-3]。改性沥青的主要成分包括基质沥青、苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)改性剂和其他助剂等几部分[4-7]。在实际生产中,对于其各组分含量的测定和分析是评价改性沥青质量的重要环节。目前,评价SBS改性沥青技术主要以物理测试方法为主,包括针入度、延度、软化点、黏度等物理性能指标[8]。这     

胶粉在改性沥青中的物化行为分析

生产胶粉改性沥青(CRMA)是实现废橡胶资源化利用及减轻环境污染的有效途径。为了研究胶粉在沥青中的物理及化学行为,采用邻苯二甲酸二丁酯(DBP)模拟沥青的轻组分,将胶粉置入DBP中,在175℃下,反应1.5 h后分离胶粉与轻组分,对轻组分进行气相色谱与质谱联用(GC-MS)分析,讨论胶粉与轻组分发生的物理化学作用;对不同条件下制备的胶粉改性沥青分离胶粉后进行红外光谱(IR)和差示扫描量热(DSC)分析,研究橡胶改性沥青中的官能团变化和热力学特性。结果表明,分离胶粉后的DBP中存在19种检出物,除含量最高的DBP外,其余物质均为胶粉浸出物或与轻组分的反应产物,即胶粉在轻组分中发生了复杂的物理化学反应。胶粉沥青样品中的—CH_2和C=C双键等特征官能团吸收峰大幅增强,橡胶分子在沥青中发生断链降解释放出小分子物质溶于沥青组分发挥改性作用;195℃、1.5 h和175℃、3.0 h制备的沥青样品DSC谱线出现了强烈的吸热峰,即处理温度过高或时间过长,可能发生胶粉过度降解、胶粉团聚或沥青老化行为,使胶粉改性沥青的物化状态发生改变,导致性能劣化。从胶粉物化变化的角度,建议制备胶粉改性沥青时,胶粉掺量(质量分数)应在20%左右,处理温度不高于195℃,处理时间不超过1.5 h。     

SBS改性沥青机理研究进展

介绍了沥青的特性、苯乙烯-丁二烯-苯乙烯三嵌段共聚物(SBS)的性能,分析了SBS与基质沥青之间的溶胀性和相容性问题,着重论述了SBS改性沥青机理的研究进展,指出机理主要分为物理共混和化学改性两类:物理共混——SBS微粒受到沥青组分中油分的作用发生溶胀而均匀分散在沥青中,SBS与沥青之间没有发生化学作用,只是一种分子间作用力;化学改性——加入添加剂使沥青和SBS之间发生加成、交联或接枝等化学反应,形成较强的共价键或离子键,改善沥青的化学性质。提出化学改性是提高SBS改性沥青路用性能的重要手段。     

基于苯甲醛交联剂的煤直接液化残渣改性石油沥青

以苯甲醛为交联剂,采用煤直接液化残渣的四氢呋喃萃取物(THFS)对石油沥青进行了改性。考察了THFS、交联剂的掺杂量以及掺混温度对改性沥青性能的影响。研究表明,当THFS的掺杂量为4 %,掺混温度为170 ℃时改性效果最佳,而且苯甲醛作为交联剂加入可使沥青改性效果更佳。利用热重-傅里叶红外光谱联用仪(TG-FTIR)、傅里叶变换红外光谱仪(FT-IR)和荧光显微镜对改性沥青进行了表征,结果表明,添加了苯甲醛的改性沥青的失重残余率较其他沥青略有提高;苯甲醛交联的改性沥青在热解过程中释放的CH₄含量减少且释放温度有所提高;改性沥青在2 924 cm^-1和2 854 cm^-1处的脂肪族-CH₂-的伸缩振动和表征苯环位取代872、810和746 cm^-1处吸收峰的透射率均有较大幅度的提高,并在1 060 cm^-1处出现C-O-C伸缩振动峰,以及荧光显微镜图像中出现新的改性粒子,表明交联剂的添加使THFS和基质沥青发生了缩合反应。     

高效凝胶色谱研究丁苯橡胶改性沥青的热老化性能

丁苯橡胶与胜利100号沥青混炼后的改性沥青。具有耐热老化的性能,适合于高等级公路用的改性沥青。W.A.达克研究了沥青分子量分布与其物性指标的关联。丁苯橡胶改性沥青的热老化前后性能的研究尚未见报道。     

DCLR与TLA共混改性沥青的性能对比

以SK-90沥青为基质沥青,分别加入相同掺量(与沥青质量比为5%、10%、15%和20%)的DCLR和TLA,利用SHRP PG、针入度分级体系、红外光谱仪和凝胶色谱仪对比分析DCLR和TLA共混改性沥青的宏观性能和微观结构的变化。结果表明,DCLR和TLA的加入均可以改善沥青的高温性能,但对沥青的低温性能和疲劳性能产生一定的不利影响。同时,根据DCLR和TLA共混改性沥青的官能团和分子量分布的变化可以判断DCLR和TLA对沥青的改性作用主要为物理改性,在某种程度上,DCLR不能完全替代TLA。     

均四甲苯改性沥青的化学结构特征

平均结构参数分析法是分析沥青类复杂分子体系化学结构的一种有效方法。通过分析比较热处理改性沥青和均四甲苯改性沥青在化学结构上的不同 ,发现均四甲苯改性沥青中有机分子的分子量较大 ,但氢含量较高 ,芳香度较小 ,主要表现为脂肪环结构的增多和甲基取代基的大量引入。氢转移、质子化、亚甲基桥的形成可能是导致这些结构特征的主要原因。     

煤沥青橡胶改质筑路油老化过程中族组成与性质变化

实验室与户外跟踪老化研究发现 ,道路沥青在使用过程中的质量蜕变主要是由于氧化作用[1,2 ]使得道路沥青中沥青质含量增加 ,改变了沥青中分散相与连续相的比例 ,致使沥青的性质发生变化 ,如软化点升高、针入度降低以及粘度增加等[3,4]。上述研究所取得的成果主要是以石油为原料的道路沥青 ,对以煤沥青为原料开发的改质筑路油研究较少。本文在成功开发煤沥青改质筑路油工艺的基础上 ,研究了改质筑路油热老化过程中族组成与性质的变化 ,由此提出煤沥青改质筑路油高温热老化过程中性质变化的主要原因。1　实验部分1 1　原料　试验所用原料为实…     

Improvements of properties of asphalt by poly(methyl methacrylate) additives

This article presents the effect of adding poly(methyl methacrylate) (PMMA) with different molecular weights on the mechanical properties of asphalt in terms of durability, strength, and resistance to rutting. By controlling the time of reaction we obtained PMMA of two different molecular weights: PMMA1 and PMMA2. The ageing properties of polymer modified asphalts were studied using the thin film over (oven) a test. A hot storage stability test was carried out for polymer modified binder. The physical properties of asphalt modified with PMMA including penetration value and softening point were examined at two different temperatures. Resilient modulus test was evaluated by a Universal Testing Machine. Results showed that an incorporation of PMMA into asphalt binder has significantly improved its properties under studies. Indirect tensile strength test and durability performance of the modified asphalts was evaluated as well. The resulted modification was found to be dependent on the polymer molecular weight. The PMMA1 exhibited effective and cheerful results.     

Influence of montmorillonite on ageing resistance of styrene–ethylene/butylene–styrene-modified asphalt

Storage-stable styrene–ethylene/butylene–styrene (SEBS)-modified (SM) asphalt was prepared by the addition of 4 mass/% SEBS and 3 mass/% organic montmorillonite (OMMT). The physical and rheological properties of SM and stable SEBS/OMMT-modified (SOSM) asphalts before and after short- or long-term thermal ageing were tested. The rheological tests showed that SOSM asphalt was more susceptible to ageing and became more flexible after ageing. The addition of OMMT restricted the swelling of SEBS in asphalt and led to an obvious susceptibility of SEBS to ageing. The structural characteristics of modified asphalt and OMMT before and after ageing were investigated by using optical microscope, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, thermal analysis, respectively. The microscopic and thermal analysis confirmed the ageing susceptibility of storage-stable SOSM asphalt.     

Thermal,damping, and mechanical properties of thermosetting epoxy-modified asphalts

Epoxy-modified asphalts (epoxy asphalts) have been widely used in the pavements of orthotropic steel bridge deck. In this paper, several effects on the properties of epoxy asphalts have been investigated in detail. First, the addition of asphalts showed no significant effects on the curing reaction and the glass transition temperature of epoxy resin. Second, the damping properties of epoxy asphalts were increased with the addition of asphalt contents. Furthermore, mechanical results showed that the stress at yield, stress at break, and tensile modulus of epoxy asphalts decreased with the increase of asphalt contents, whereas the strain at break increased with the increasing asphalt contents. The morphology of phase separation for epoxy asphalts was also observed.     

增容剂对煤直接液化残渣改性沥青低温性能的影响

为了评价不同增容剂对煤直接液化残渣改性沥青低温性能的影响,首先,通过正交实验确定出三种增容剂（硅烷偶联剂、苯甲醛、二甲苯）各自的最佳掺量及掺入方式;其次,采用双边缺口拉伸（DENT）试验评价加入三种增容剂后沥青的低温抗延性断裂性能;最后,结合SEM照片并利用Image Pro plus图像处理软件计算加入三种增容剂后沥青中煤直接液化残渣的分散面积比,以定量地表征三种增容剂对煤直接液化残渣改性沥青低温性能的改善效果。结果表明,加入适量增容剂在一定程度上有助于煤直接液化残渣在沥青中的分散,提高两者之间的相容性,保持煤直接液化残渣改性沥青体系的长期稳定状态,避免因煤直接液化残渣的沉淀聚集而在相界面产生应力集中,增强煤直接液化残渣改性沥青的低温抗延性断裂性能。三种增容剂对煤直接液化残渣改性沥青低温性能改善效果不同,硅烷偶联剂最优,次之为苯甲醛,最差为二甲苯。     

Glass transition measurements of asphalts by DSC

The glass transition temperature (T_g), measured by Modulated Differential Scanning Calorimetry (MDSC), is related to the flow characteristics of asphalt at low temperatures as is the rate of change of the creep stiffnessm. This study compared the glass transition temperature of different asphalts (neat, chemically modified, and crumb rubber modified asphalts) with the creep stiffness, the rate of change of creep stiffness, and the low specification temperature of the continuous PG grading of those asphalts.From the rheological data (BBR) and the thermal data (MDSC) for the virgin and the modified asphalts, the modified products had the same variations of values ofm, S, and T_g at lower temperatures as those of their corresponding virgin asphalts. A correlation between the T_g andm value was observed for both the modified and unmodified asphalts. Since DSC measurements for asphalt low temperature properties use less operator time, less sample, and have less measurement and operator error than rheological methods, T_g has promise to be considered as a fast and easy laboratory method to obtain the low temperature useful range of asphalts in pavements.The authors would like to acknowledge Susan P. Needham for her work in conducting rheological testing for the modified and unmodified asphalts.     

基于醛类交联剂的煤焦油沥青族组分改性石油沥青

以中温煤焦油沥青的四氢呋喃萃取物(THFS)对石油基质沥青进行改性,考察了掺混量、掺混温度和不同种类交联剂对改性沥青性能的影响,确定了THFS最佳掺混量为8%,最佳掺混温度为135℃,甲醛交联剂的最佳掺混量为0.8%,三聚甲醛的最佳掺混量为0.2%。考察了两两和单族组分对基质沥青的改性性能,发现重油(HS)使得改性沥青的针入度、延度增大,沥青烯(A)和甲苯不溶四氢呋喃可溶物(PA)提高感温性,软化点升高。随着醛类交联剂的添加,提高了改性沥青的抗老化性能;甲基(CH_3)、亚甲基(CH_2)透射峰强度逐渐变强,770-730 cm~(-1)、710-690 cm~(-1)和770-810 cm~(-1)苯环取代透射峰强度逐渐增强,1 010~(-1) 270 cm~(-1)处C-O-C伸缩振动峰逐渐增强;热解峰温向高温移动,残炭率增加2%;改性粒子呈现一种连续的流线分布,添加三聚甲醛的改性沥青的流线分布更加集中。     

Thermo-rheological properties and storage stability of SEBS/kaolinite clay compound modified asphalts

Styrene-ethylene-butadiene-styrene block copolymer (SEBS) modified asphalts with improved high-temperature storage stability are prepared by incorporating kaolinite clay (KC) into the SEBS compounds. The effect of KC on the high-temperature storage properties, dynamic rheological and mechanical properties and morphologies of the modified asphalts are studied. It is found that the SEBS/KC ratio in the compound has a great effect on the high-temperature storage behavior. The modified asphalts are stable when the ratio of SEBS/KC is around 2. However, KC decreases the dynamic rheological and mechanical properties of the modified asphalts to some extent. The high-temperature storage property can be increased by improving the compatibility and decreasing the density difference between SEBS and asphalt.     

Aging properties and mechanism of the modified asphalt by packaging waste polyethylene and waste rubber powder

For the consideration of the environmental and economic issues, retrieved packaging waste polyethylene and waste rubber powder were selected as modifiers to modify the ordinary oil asphalt, and the rotating film oven test was adopted to study the aging process of the modified asphalt. The results showed that the performance of the modified asphalt deteriorated, as indicated by the increase in the softening point and the reduced ductility and penetration. However, compared with nonmodified asphalt, the rangeability of the performance indicators of the modified asphalt before and after aging became narrow, indicating that the aging properties of the modified asphalt were improved. In the modified asphalt system, the swelling of the polymer modifiers was caused by the absorption of the light components of the asphalt, thereby reducing the formation of asphaltenes in the aging process. The polymer modifiers absorb the light oil of the asphalt, which can reduce the content of free radicals and improve the aging properties of the asphalt. In addition, the waste rubber power containing antioxidants and anti‐ozone agents effectively improves the antiaging properties of the asphalt. Copyright © 2012 John Wiley & Sons, Ltd.