基于分子模拟的沥青胶结料物理老化机理研究

利用Materials Studio软件建立沥青的四组分模型,利用体积温度曲线得到了该沥青模型的玻璃化转变温度,同时利用差示扫描量热（DSC）试验验证了沥青模型所得玻璃化转变温度的可靠性,并在低于玻璃化转变温度下利用分子动力学从微观上对沥青分子的物理老化现象进行模拟与分析.结果表明：在低于沥青玻璃化转变温度的等温等压条件下,沥青模型随着时间的延长,出现了自由体积减小、密度增大的物理老化现象;低温下沥青质和胶质导致沥青活动性降低,出现了物理老化现象,实现物理老化的微布朗运动的分子活动力主要来自饱和分和芳香分.     

Sasobit温拌剂对改性沥青混合料体积参数的影响

测试了不同温度条件下,胶结材料为SK、壳牌以及克拉玛依等三种SBS改性沥青及克拉玛依基质沥青中添加Sasobit的混合料的毛体积相对密度、空隙率、矿料间隙率、沥青饱和度等体积参数。结果表明:Sasobit可以在一定温度范围内有效地改善沥青的粘度,降低沥青混合料的成型温度,从而使毛体积密度增大、空隙率减小、矿料间隙率减小、沥青饱和度增加,但这种改善有一定的作用范围;Sasobit对基质沥青敏感性高于改性沥青;对于不同的改性沥青Sasobit对其降温区间也有一定的差异;加入Sasobit都能降低沥青混合料室内成型温为27℃,降低沥青混合料室内成型温度12℃。     

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...     

高黏改性沥青高温流动特性及感温性能研究

采用2种不同的高黏添加剂复配SBS改性沥青制备高黏改性沥青,通过流动模型及黏温曲线方程对高黏改性沥青的流动特性与感温性能进行研究。结果表明:采用流变指数来描述改性沥青的流动性具有良好的相关性,Ⅰ型、Ⅱ型高黏改性沥青和SBS改性沥青的流变指数随着温度的升高逐渐增大,温度为175℃时已接近牛顿流体;活化能研究表明,Ⅰ型高黏改性沥青的活化能较大,抵抗外界变形的能力较强,SBS改性沥青次之,Ⅱ型高黏改性沥青活化能相对最小。     

沥青混合料松弛特性的时间-温度-老化等效关系

通过不同老化程度和不同温度下AC-13C型沥青混合料的应力松弛试验,结合时间-温度的等效关系原理和WLF公式分析,得到了不同老化程度沥青混合料的松弛模量主曲线簇及其黏弹性参数值;以材料黏度的自由体积理论为基础,推导出了沥青混合料的老化程度与温度、时间之间的等效关系式,并通过已有应力松弛试验数据进行了验证.结果表明:老化后的沥青混合料应力松弛特性可以用未老化沥青混合料在较低温度或较低荷载作用时间下的性能来分析.     

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。     

多尺度纳米材料对再生沥青长期老化性能的影响

研究了由不同掺量有机蛭石（OEVMT）和纳米氧化锌（Nano ZnO）组成的多尺度纳米材料对再生沥青长期热氧和光氧老化性能的影响。利用薄膜烘箱对普通基质沥青进行老化以制得老化沥青,采用熔融共混方法,先将老化沥青、普通基质沥青以及再生剂按照一定的比例混合以制得再生沥青,再将多尺度纳米材料加入到再生沥青中制得多尺度纳米材料改性再生沥青。采用压力老化箱老化（PAV）和加速紫外光老化（UV）分别模拟再生沥青的长期热氧老化和光氧老化条件。通过传统物理性能试验和动态剪切流变试验评价了再生沥青的老化性能。结果表明:添加多尺度纳米材料提高了再生沥青老化前的高温稳定性、剪切变形抵抗力和弹性行为,但一定程度上削弱了其低温塑性变形能力;多尺度纳米材料有效改善了再生沥青长期热氧和光氧老化抵抗力;综合考虑长期老化性能数据,多尺度纳米材料的推荐掺量（质量分数）为1%OEVMT+3%NanoZnO。     

Effect of different high viscosity modifiers on rheological properties of high viscosity asphalt

High viscosity asphalt (HVA) has been a great success as a drainage pavement material. However, the larger porosity of drainage asphalt mixtures weakens the cohesion and adhesion and leads to premature rutting, water damage, spalling and cracking. The purpose of this study was to investigate the rheological properties of HVA prepared using different high viscosity modifiers through conventional tests, Brookfield viscosity tests, dynamic shear rheometer tests and bending beam rheometer tests. The conventional performance results demonstrated SBS + rubber asphalt (SRA-1/2) exhibited excellent elastic recovery and low-temperature flexibility. The 60°C dynamic viscosity results indicated TPS + rubber asphalt (TRA) had the excellent adhesion. The rotational viscosity results and rheological results indicated that SRA-2 not only exhibited excellent temperature stability and workability, as well as excellent resistance to deformation and rutting resistance, but also exhibited excellent low-temperature cracking resistance and relaxation performance. Based on rheological results, the PG classification of HVA was 16% rubber + asphalt for PG76-22, 20% rubber + asphalt for PG88-22, TRA and SRA-1/2 for PG88-28. From comprehensive evaluation of the viscosity, temperature stability and sensitivity, as well as high/low temperature performance of HVA, SRA-2 was found to be more suited to the requirements of drainage asphalt pavement materials.     

仓储式橡胶沥青零剪切粘度的确定

首先,运用低频率震荡测试法对基质沥青、仓储式橡胶沥青及其RTFOT短期老化产物进行了测试;其次,运用图形外延法、Cross模型拟合法及Carreau模型拟合法对各材料的零剪切粘度进行了测定;最后,对基质沥青进行了蠕变恢复试验,通过蠕变阶段和恢复阶段沥青的应变响应的计算,得出了静态施载作用下基质沥青的零剪切粘度。研究表明：基质沥青在低频震荡测试中,随着频率的降低会进入粘度稳定阶段,可以用图形外延法得到零剪切粘度;然而对于RTFOT老化后的橡胶沥青,在测试条件下未进入粘度稳定阶段,无法通过图形外延法测算零剪切粘度;由Cross模型拟合的结果都大于同样材料Carreau模型拟合结果。     

以表观粘度为参数建立沥青老化动力学模型

介绍了沥青的老化机理,研究了2种基质沥青老化后表观粘度的变化,以表观粘度为参数建立了沥青一级老化动力学模型,并用该动力学模型对这2种沥青的抗老化性能进行了研究,求得了动力学参数。实验结果表明,这2种沥青老化后表观粘度均升高,AH-70沥青抗老化性能优于AH-90沥青。以表观粘度为参数建立的沥青老化动力学模型较好地表征了沥青老化过程。     

Micro-structural and rheological characteristics of SBS-asphalt blends during their manufacturing

Two styrene–butadiene–styrene block (SBS) copolymers which differ in weight average molecular weight and two base asphalts (from local crude source, Argentina) had been blended under different experimental conditions. Rotational viscosity, fluorescence microscopy, size exclusion chromatography (SEC) and FT-IR spectrometry were used in order to study the rheological and morphological changes of the blends during their manufacturing. Our results show that the high shear rate and temperature used during this procedure induce the SBS copolymer degradation and the degradation fragments distribution into maltenic asphalt phase. These events are responsible for the observed changes. The optimal time which produces the best rheological properties of modified asphalt depends on the blend composition and on the shear rate used.     

基于Arrhenius图的沥青使用寿命预估方法研究

根据Arrhenius方程分析了沥青在加速热老化试验条件下的临界老化时间与老化温度的关系，提出利用临界老化时间与老化温度绘制Arrhenius图，以及利用Arrhenius图预估沥青使用寿命的试验方法。采用该方法估算了所选2种沥青的使用寿命，并分析了影响沥青寿命预估的因素。采用该方法估算的沥青寿命值呵为路面寿命周期成本分析和路面养护时机的选择提供参考。     

Effect of styrene-butadiene-styrene copolymer on the aging resistance of asphalt: An atomistic understanding from reactive molecular dynamics simulations

To reveal the potential influence of styrene-butadiene-styrene (SBS) polymer modification on the anti-aging performance of asphalt, and its mechanism, we explored the aging characteristics of base asphalt and SBS-modified asphalt by reaction force field (ReaxFF) and classical molecular dynamics simulations. The results illustrate that the SBS asphalt is more susceptible to oxidative aging than the base asphalt under oxygen-deficient conditions due to the presence of unsaturated C=C bonds in the SBS polymer. In the case of sufficient oxygen, the SBS polymer inhibits the oxidation of asphalt by restraining the diffusion of asphalt molecules. Compared with the base asphalt, the SBS asphalt exhibits a higher degree of oxidation at the early stage of pavement service and a lower degree of oxidation in the long run. In addition, SBS polymer degrades into small blocks during aging, thus counteracting the hardening of aged asphalt and partially restoring its low-temperature cracking resistance.     

炭黑沥青胶结料旋转粘度规律研究

将炭黑作为改性剂,对基质沥青进行改性。通过室内试验,对不同配制温度的炭黑沥青进行旋转粘度实验。旋转粘度实验,是用来测定沥青的表观粘度,评价沥青高温性能的重要指标之一。本文对比分析不同配制温度、不同转子型号、不同转速、不同实验温度对炭黑沥青旋转粘度的影响。结果表明,配制温度越高,炭黑沥青的旋转粘度越高;在不同转子型号下,测得的旋转粘度的大小关系为:21~#27~#28~#29~#;在温度较低时,旋转粘度随着转速的增加变化不大,当温度较高时,转速对旋转粘度的影响很小。通过不同试验温度,绘制出的黏温曲线,结果表明,温度升高,炭黑沥青的旋转粘度下降,下降的程度随着温度的升高而降低。     

光氧老化对沥青表观粘度的影响

介绍了沥青的光氧老化机理,研究了四种沥青室内、外光氧老化后表观粘度的变化,以表观粘度为参数建立了沥青一级光氧老化动力学模型,并用该动力学模型对这四种沥青的抗光氧老化性能进行了研究,求得了动力学参数。     

沥青玛蹄脂粘弹性特性静态蠕变试验研究

为了深层揭示沥青玛蹄脂的粘弹性特性,采用Burgers粘弹性模型作为粘弹性力学行为的数学描述,通过沥青玛蹄脂静态剪切蠕变试验,研究了温度对沥青玛蹄脂粘弹性特性的影响.结果表明:Burgers粘弹性模型四参数随温度升高呈负指数递减;沥青玛蹄脂蠕变柔度随温度升高呈正指数增加;沥青玛蹄脂的瞬时弹性随温度升高而递减;粘性流动随温度升高而递增;延迟弹性在蠕变初期随着温度升高先增加后减小,在蠕变中、后期随着温度升高而递减;沥青玛蹄脂的粘流动性弹比随温度升高呈正指数增加,在高温区其粘性远远大于弹性,沥青玛蹄脂表现为粘性.     

基于FTIR的SBS改性沥青老化特性分析

采用宏观和微观分析相结合的方法,细致区分了SBS改性沥青中沥青相和SBS相各自的老化特性.通过常规指标试验评价了SBS改性沥青热氧老化前后的物理性能差异,并将其与基质沥青对比,得出SBS改性沥青的老化规律为黏度增加、变形能力下降.采用傅里叶红外光谱技术(FT-IR)定量分析了SBS改性沥青老化前后结构与性能的关系,发现...     

Rheological properties of water-in-diesel fuel emulsions

The addition of water dispersed phase into the diesel continuous phase will lead to the formation of water-in-diesel (W/D) emulsion, which significantly reduces the pollution level of NO_x and particulate matters in the diesel engines. The study of the rheological properties of stable W/D emulsions is important to understand the flow characteristics of these emulsions. Pure diesel fuel and three samples of W/D emulsions (10%, 20%, and 30% by volume water) were examined. Pure diesel fuel exhibits a Newtonian profile since its viscosity remains constant with the shear rate. All W/D emulsions display higher viscosity than diesel fuel with non-Newtonian flow behaviour of yield pseudoplastic response. The viscosity of the W/D emulsions decreases with the shear rate and water addition. The flow behaviour of pure diesel fuel can be described by the Power law model. The Casson model very sufficiently fits the flow behaviour of different W/D emulsions.     

优质氧化沥青研究

我国沥青原料的性能较差,需改性才能适用于油毡生产工艺。作者分析了普通氧化沥青,调合氧化沥青,催化氧化沥青和调合催化氧化沥青性质改变的情况,特别对沥青的针入度和低温柔性作了具体研究,认为调合催化氧化对改变沥青的性能效果最优。     

不同剂量SBS改性沥青粘度性能分析

介绍了粘度试验的原理,分析了基质沥青和改性沥青的流变指标随温度变化的情况,通过测试基质沥青和改性沥青的粘度,对进一步研究沥青的流变性具有重要意义,同时指出沥青结合料的粘度与混合料的路用性能密切相关。