多聚磷酸改性石油沥青的性能及反应机理

研究了添加不同多聚磷酸掺量改性的石油沥青的性能,探讨了多聚磷酸与石油沥青的反应机理。结果表明,随多聚磷酸掺量的增加,石油沥青的软化点、135℃运动黏度、车辙因子、针入度指数、针入度比等技术指标逐渐增大,而RTFOT老化前后10℃延度值、针入度值均逐渐下降。此外,还研究了多聚磷酸掺量对石油沥青四组分分布的影响,结果显示多聚磷酸加入后,石油沥青沥青质含量增加,胶质含量降低,饱和分和芳香分变化较少。     

“多聚磷酸改性沥青混合料应用技术研究”试验路在昌图县昌法线成功铺筑

<正>辽宁省交通厅重点科研顶目"多聚磷酸改性沥青混合料应用技术研究"试验路在昌图县昌法线成功铺筑。多聚磷酸加入到沥青中可有效提高沥青的高温性能,改善SBS改性沥青的存储稳定性,增强沥青耐老化性能等优点。在不降低路用性能的情况下,可替代部分SBS改性剂,同时,可降低改性沥青的工程成本。其制备工艺     

多聚磷酸在SBS改性沥青中的应用研究

研究了多聚磷酸对SBS改性沥青性能的影响,分别考察了降低SBS用量、基质沥青种类和多聚磷酸用量对克拉玛依沥青改性性能的影响。结果表明：使用多聚磷酸可以在不影响改性沥青的高温性能的情况下降低SBS的用量,提高改性沥青的抗老化性能,降低改性沥青的离析值,但同时改性沥青的低温性能会显著降低;对沥青适当处理有助于得到储存稳定的改性沥青;多聚磷酸用量过大会使沥青粘度显著提高,不利于混合料的施工,用量为1％时较为合适。     

克拉玛依沥青与SBS相溶性研究

通过对基质沥青组成和SBS分子结构对SBS改性沥青性质的影响研究,表明了沥青组成中沥青质和芳香烃含量对改性沥青性质影响最大;SBS分子结构中随着苯乙烯含量的增加,改性沥青样品的软化点有降低趋势,SBS分子量降低,改性沥青样品的储存稳定性提高。提高克拉玛依沥青沥青质含量,降低SBS分子量,可以有效改善克拉玛依沥青与SBS的相溶性。     

化学助剂对SBS改性沥青的性能影响初探

通过加入化学助剂制备一种反应性SBS改性沥青,研究助剂加入量对改性沥青性能及高温储存后性能影响,对比其与高速剪切工艺所得改性沥青性能差异,并利用荧光显微照片分析两者微观形态的不同。结果表明：改性沥青性能随着助剂加入量增加先变好后变差。助剂加入量为0.6%时,改性沥青低温和高温性能最好;高温储存后延度与老化延度有一定的下降,针入度与软化点变化较小;加入助剂比高速剪切制得的改性沥青的低温性能和储存稳定性更好;荧光显微照片显示,剪切后SBS以颗粒的形式分散在沥青中,而加助荆使SBS与沥青形成均匀连续的网状结构。     

多聚磷酸改性沥青研究

通过组分分析、流变力学试验及常规试验,揭示了多聚磷酸可以改变沥青的胶体结构形态的改性机理;对多聚磷酸的适宜剂量进行了优化及论证;优化出的多聚磷酸改性C级石油沥青的感温性大幅度下降,抗车辙性能显著提高,可由PG52—22级提升至PG70—22级;多聚磷酸对沥青的低温及疲劳特性无不良影响,但是,经薄膜老化后,改性沥青的弹性分量显著增大,抗短期老化性能下降。研究结论可作为工程应用的基础。     

废橡胶改性沥青的储存稳定性研究

研究了维他连接剂(TOR)、多聚磷酸(PPA)、硫化交联体系(硫磺、稳定剂及硫化促进剂)和原料基质沥青对改性沥青储存稳定性的影响。结果表明：使用TOR和PPA可在一定程度上降低改性沥青的离析软化点差,改善改性沥青的储存稳定性;在硫化体系中,硫磺及稳定剂的加入可改善改性沥青的储存稳定性,且其加入量都有最佳值,促进剂的复合配伍有利于提高改性沥青的储存稳定性;基质沥青对改性沥青的储存稳定性影响较大,基质沥青的芳香度高时,有利于胶粉在沥青中的溶胀,有助于体系中发生脱硫降解和交联反应,达到良好的改性效果。     

乳化条件对高黏改性乳化沥青储存稳定性的影响

考察了制备工艺(乳化温度和磨出口压力)、乳化剂用量和改性沥青中SBS含量对高黏改性乳化沥青储存稳定性的影响。通过激光粒度仪测定高黏改性乳化沥青平均粒径,探讨高黏改性乳化沥青平均粒径与其储存稳定性的相关性。结果表明:高黏改性乳化沥青的储存稳定性数值随乳化温度的升高和改性沥青中SBS含量的增加均呈先降低后增加趋势,随胶体磨出口压力和乳化剂用量的增加均呈先降低后趋于变缓趋势;高黏改性乳化沥青的储存稳定性数值与其平均粒径呈正相关。在优化工艺条件下,即SBS改性沥青温度为165℃、乳化剂溶液温度为55℃、磨出口压力为0.2MPa、乳化剂用量为0.4%及改性沥青中SBS含量为3.2%时,制备出的高黏改性乳化沥青已成功应用在2014年和2016年的西长安街大修工程中。     

PPA对改性沥青及其混合料低温性能影响

分别通过弯曲梁流变试验(BBR)和半圆弯拉试验(SCB)分析多聚磷酸(PPA)对改性沥青/沥青混合料低温性能的影响.结果表明:PPA的加入改善了基质沥青及其混合料的低温性能,掺量宜为0.8％-1.6％;0.4％掺量PPA对TB复合SBS改性沥青及其混合料的低温有较好的改善效果;PPA对于沥青低温性能的提升能力随着温度降...     

表面活性剂型温拌剂对沥青感温性能的影响

考察了一种油溶性表面活性剂型温拌剂及其用量对SK AH-70沥青和SBS改性沥青感温性能(包括针入度指数(PI)、当量软化点(T_(800))、当量脆点(T_(1.2))和黏温指数(VTS))的影响。结果表明:温拌剂用量为0~2.0%时,温拌剂降低了SK AH-70沥青和SBS改性沥青的PI,使两种沥青中温时的感温性能变差;温拌剂略微增加了SBS改性沥青的T_(1.2),从而使SBS改性沥青的低温抗裂性能略微变差,而其对SK AH-70沥青的低温抗裂性能没有明显影响;温拌剂降低了两种沥青的T_(800),使其在中高温时的抗塑性变形能力变差,随其用量增加,两种沥青T_(800)均呈降低趋势,且SBS改性沥青T_(800)降低的幅度大于SK AH-70沥青;温拌剂使两种沥青在高温时的温度敏感性呈略有降低趋势。     

躺滴法表征沥青的表面自由能

 表面自由能是用来确定沥青材料自身的黏聚功（黏聚强度）以及沥青与石料之间的黏附功的重要参数。此外,沥青混合料（包括沥青、石料和空气）的水敏感性也可使用沥青与石料的表面自由能参数进行评价。笔者采用躺滴法测定了几种战略公路研究计划(SHRP)沥青与液体的静态接触角,使用Owens-Wendt法确定了沥青的表面自由能。结果表明,躺滴法得到的沥青表面自由能与由接触角得到的数值比较接近,说明可以应用躺滴法来测定沥青的表面自由能。由沥青的表面自由能表征的沥青黏聚能结果与pull-off强度试验结果相吻合。     

The Application of Grey System Theory to Correlate Chemical Composition and Surface Free Energy of Asphalt Binders

Abstract

Grey correlation analyses were carried out to determine which chemical components and chemical elements of asphalt binders are most related to surface free energy (SFE) measurements of asphalt binders. The total, dispersive, and polar SFE values were calculated for 23 Strategic Highway Research Program (SHRP) asphalt binders based on contact angle measurements by the sessile drop method and the chemical composition data of the 23 binders was obtained from previously published information. During the Grey correlation analysis, it was found that polar aromatics content has the largest effect on the total SFE and dispersion component of SFE, whereas saturates made the largest contribution to the polar component of SFE. Carbon (C) and hydrogen (H) made the largest contribution to the total, dispersion, and polar SFE; vanadium (V) content has the smallest effect on the total surface free energy, including its dispersion and polar parts.     

A Study on the Aging Kinetics of PPA Modified Asphalt

Abstract

Asphalt binders have been chemically modified with polyphosphoric acid (PPA) since the early 1970s. A large number of research papers have shown that the addition of PPA to asphalt improved the high-temperature stability and rheological properties of asphalt. In this article, research on the aging kinetics of PPA-modified asphalt was carried out based on determining the softening point of asphalts at different aging time and temperatures. The results showed that the aging reaction of PPA-modified asphalt followed the first-order reaction; the aging reaction rate of PPA-modified asphalt was lower than that of original asphalt; the activation energy of PPA-modified asphalt was higher than that of original asphalt; and the anti-aging performance of PPA-modified asphalt was better than that of original asphalt.     

Evaluation of rutting resistance of asphalt binders and asphalt mixtures modified with polyphosphoric acid

In this research, a polyphosphoric acid (PPA) additive was used to modify a performance graded binder (PG 58-22). Experimental program included use of three PPA contents (0.5%, 1%, and 1.5%) by weight of bitumen and use of antistripping limestone aggregates. High-temperature rheological properties of asphalt binders were evaluated through the frequency sweep test. Complex modulus test was also used to evaluate rutting characteristics of asphalt mixtures. Results showed that PPA significantly improved rutting resistance of both unmodified asphalt binder and unmodified asphalt mixture, especially for the asphalt binder.     

Effect of Chemical Nature on the Susceptibility of Asphalt to Aging

The knowledge of the factors affecting the susceptibility of asphalt to aging can be of help when selecting the asphalt binders for the construction of durable pavements. Investigated were the aging-induced changes in the chemical composition and colloidal nature of asphalts differing in origin and technology. It was shown that the course of the changes in the generic composition of asphalt upon aging under laboratory conditions depends on the chemical type of the feedstock from which the asphalt has been derived. During aging of the asphalts from the paraffin-naphthenic crudes, the resins undergo partial decomposition, which results in the increase of the cyclic fraction content. Although the increase of the asphaltene content in air-blown asphalts after the Thin Film Oven Test was found to be lower than that in the corresponding straight-run asphalts, the much higher value of the instability index and smaller size distribution of asphaltenes in the air-blown asphalts permit us to expect that their utilization as binders in pavement construction will lead to the reduction of pavement durability. It follows from the results of this study that not only the generic composition but also the structure of the fractions affect the resistance of asphalt to aging.     

Effect of Chemical Nature on the Susceptibility of Asphalt to Aging

Abstract

The knowledge of the factors affecting the susceptibility of asphalt to aging can be of help when selecting the asphalt binders for the construction of durable pavements. Investigated were the aging-induced changes in the chemical composition and colloidal nature of asphalts differing in origin and technology. It was shown that the course of the changes in the generic composition of asphalt upon aging under laboratory conditions depends on the chemical type of the feedstock from which the asphalt has been derived. During aging of the asphalts from the paraffin–naphthenic crudes, the resins undergo partial decomposition, which results in the increase of the cyclic fraction content. Although the increase of the asphaltene content in air-blown asphalts after the Thin Film Oven Test was found to be lower than that in the corresponding straight-run asphalts, the much higher value of the instability index and smaller size distribution of asphaltenes in the air-blown asphalts permit us to expect that their utilization as binders in pavement construction will lead to the reduction of pavement durability. It follows from the results of this study that not only the generic composition but also the structure of the fractions affect the resistance of asphalt to aging.     

Study on Aging Kinetics of Saudi Arabian Paving Asphalt

The changes of n-pentane asphaltene content, penetration, softening point, and ductility of two Saudi Arabian paving asphalts have been studied during aging. Further, aging kinetics of asphalt, based on the change of n-pentane asphaltene content, has been studied. Some correlative kinetic parameters were calculated and the aging kinetics equation of asphalt was gained. The value calculated depending on the equation was in accordance with the experimental data. And the relationship between the composition of the high grade paving asphalt and its aging resistant performances was revealed. It showed that the aging of high grade paving asphalt was a first-order reaction. AH-70 paving asphalt has the following characteristics: higher reaction active energy, less reaction velocity constant, lower aging velocity, and better aging resistance performance compared with AH-90 paving asphalt. The changes of penetration, softening point, and ductility of asphalt during aging further proved that the kinetic model is reliable.     

PERFORMANCE/MICROSTRUCTURE RELATIONSHIP OF BLENDS OF ASPHALTS WTTH TWO INCOMPATIBLE POLYMERS

Using microscopic techniques by UV fluorescence reflexion. It was possible for the first time to observe the natural segregation of two incompatible polymers (a polyolefln and a SBS triblock copolymer 5:1) In several asphalts. This method helped in identifying and understanding the relationship between microstructure and performance of polymer/asphalt blends. Performance of the binders such as elongations! behaviour, low temperature flexibility and high temperature performance were studied before and after ageing. The polydispersity of the phases and the fineness of the SBS dispersion were shown to be very sensitive to the blending conditions, the composition of the asphalt and Its susceptibility to ageing. The ability of the dispersed SBS to form a continuous matrix under elongational stress was crucial to observe elastomeric behaviour. It was shown that there was an optimum in the asphaltene content in order to allow the elastomeric matrix formation without any loss in cohesion at the polymer/asphalt interface as visualized by microscopy     

Study on Aging Kinetics of Saudi Arabian Paving Asphalt

Abstract

The changes of n-pentane asphaltene content, penetration, softening point, and ductility of two Saudi Arabian paving asphalts have been studied during aging. Further, aging kinetics of asphalt, based on the change of n-pentane asphaltene content, has been studied. Some correlative kinetic parameters were calculated and the aging kinetics equation of asphalt was gained. The value calculated depending on the equation was in accordance with the experimental data. And the relationship between the composition of the high grade paving asphalt and its aging resistant performances was revealed. It showed that the aging of high grade paving asphalt was a first-order reaction. AH-70 paving asphalt has the following characteristics: higher reaction active energy, less reaction velocity constant, lower aging velocity, and better aging resistance performance compared with AH-90 paving asphalt. The changes of penetration, softening point, and ductility of asphalt during aging further proved that the kinetic model is reliable.     

PERFORMANCE/MICROSTRUCTURE RELATIONSHIP OF BLENDS OF ASPHALTS WTTH TWO INCOMPATIBLE POLYMERS

ABSTRACT

Using microscopic techniques by UV fluorescence reflexion. It was possible for the first time to observe the natural segregation of two incompatible polymers (a polyolefln and a SBS triblock copolymer 5:1) In several asphalts. This method helped in identifying and understanding the relationship between microstructure and performance of polymer/asphalt blends. Performance of the binders such as elongations! behaviour, low temperature flexibility and high temperature performance were studied before and after ageing. The polydispersity of the phases and the fineness of the SBS dispersion were shown to be very sensitive to the blending conditions, the composition of the asphalt and Its susceptibility to ageing. The ability of the dispersed SBS to form a continuous matrix under elongational stress was crucial to observe elastomeric behaviour. It was shown that there was an optimum in the asphaltene content in order to allow the elastomeric matrix formation without any loss in cohesion at the polymer/asphalt interface as visualized by microscopy