纳米蒙脱土对沥青愈合性能的影响研究

通过“疲劳-愈合-疲劳”试验评价纳米蒙脱土(NMMT)对沥青自愈合性能的影响,并且将愈合指标与物理性能指标进行拟合。结果表明NMMT改性沥青的自愈能力有所增强,且掺量对其自愈能力有较大的影响,随着掺量的增加其初始模量恢复能力逐渐减弱,但自愈后所恢复的模量其抵抗荷载作用的能力有所增强;当掺量为1%时改性沥青具有较好的自愈性能;改性沥青自愈后初始模量恢复的能力HI与软化点指标存在着较强的线性关系,通过软化点可以较好的评价其初始模量的恢复能力。     

SBS改性沥青老化分析研究

阐述了SBS改性沥青的老化特性,分别探讨了在热氧老化和紫外光氧老化前后改性沥青物化性能的差异,并且从改性沥青的针入度、软化点、延度和黏度方面进行探讨。一般而言,改性沥青经老化后针入度降低,软化点升高,延度降低,黏度升高。     

沥青的老化机理与性能研究

介绍了沥青的老化机理。介绍通过室内模拟加速老化试验(短期热氧老化试验、长期热氧老化试验和长期光热老化试验)和对沥青的四组分分析,研究了沥青在拌和、铺筑和使用过程中光氧、热氧老化机理。以及沥青老化表征的一些方法。在老化过程中沥青的芳香分含量均显著减少,沥青质的含量均明显增加,饱和分只有少量的挥发衰减;在短期热氧老化和长期光氧老化试验中胶质含量均降低,但在长期热氧老化中胶质含量增加。     

纳米蒙脱土对沥青物理流变性能的影响研究

为了改善沥青的物理流变性能,采用蒙脱土对基质沥青及SBS改性沥青进行改性,利用旋转薄膜老化对沥青样品进行了老化以研究其热氧老化性能.通过采用针入度、延度、软化点、动态剪切及弯曲蠕变等试验,对纳米蒙脱土对沥青物理流变性能的影响进行了分析.研究结果表明,在沥青中掺入纳米蒙脱土后有效的提高了老化前后沥青的高温流变性能.然而,...     

雾封层材料的抗老化性能研究

为提出厂拌乳化沥青冷再生面层配合比设计,以通辽高速公路面层铣刨料为材料,结合级配试验、马歇尔试验、干湿劈裂试验.确定了最佳配合比,并检验了再生混合料的高温稳定性、低温抗裂性.水稳定性等指标,证明该再生混合料配合比满足高速公路面层的各项要求.     

竹类生物油改性沥青的抗老化性能

文中旨在研究由竹类生物质慢速热解生物油改性沥青的抗老化性能。将基质沥青与生物油（0%、6%、12%）拌合制备生物沥青,并对生物沥青进行老化试验。采用傅里叶变换红外光谱法对老化和未老化沥青进行测试,通过计算沥青的羰基指数、亚砜指数以及老化活化能,分析发现生物沥青的亚砜指数低于基质沥青,同时生物沥青的老化活化能高于基质沥青。表明生物沥青具有比基质沥青更好的抗老化性能。     

纳米有机膨润土改性沥青的试验研究

通过不同掺量纳米有机膨润土改性沥青的对比试验,研究了纳米有机膨润土改性沥青的特性,结果表明纳米有机膨润土改性沥青的感温性、高低温稳定性较普通沥青都有所改善,得出纳米有机膨润土的最佳掺量为5%~7%。     

紫外光吸收剂UV326插层OMMT对沥青性能的影响

模拟光氧老化、热氧老化,分析紫外线吸收剂UV326插层OMMT复合改性剂对沥青材料的物理性能和老化性能的具体影响。结果表明,紫外光吸收剂UV326插层OMMT制备沥青能有效抑制沥青的老化,提高沥青的抗老化性能。用拟合公式拟合UV326/OMMT沥青在老化实验中部分性能指标的变化趋势,得出实验范围中的抗老化性能对应的最佳掺量为3wt%附近。     

沥青光老化机理及抗光老化改性沥青技术研究

通过加速老化试验对沥青光老化机理进行研究,采用丁苯橡胶和纳米TiO2分别对沥青进行改性,研究表明,丁苯橡胶和纳米TiO2对沥青抗光老化性能均具有明显的改善作用,改善效果与纳米TiO2的掺量成正比,纳米TiO2对沥青抗光老化性能的改善效果优于丁苯橡胶。     

复配阻燃沥青氧指数和路用性能研究

基于阻燃剂和协同剂复配技术,设计了复配阻燃沥青.通过氧指数试验,研究协同剂对复配阻燃沥青阻燃性能的影响;采用协同阻燃效率SE及阻燃性价比EV指标,比较阻燃剂和协同剂组成的复配阻燃体系的协同阻燃效果;采用沥青常规性能试验和动态剪切流变试验,分析复配阻燃体系对沥青路用性能的影响.结果表明,合适的复配阻燃体系在适当的复配比例下,可以有效地提高沥青的阻燃性能和高温性能.     

Effect of pre-heating duration and temperature conditioning on the rheological properties of bitumen

It is well known that overheating asphalt bitumen can lead to oxidation and stiffening. While heating bitumen is an essential protocol in sample preparation, it is important to identify the oven setting time and temperature for lab testing. Current AASHTO standards do not specify exact oven settings for bitumen sample preparation prior to laboratory testing. This study is evaluating the effect of oven heating duration and pouring temperature during sample preparation in the rheological properties of neat and polymer-modified bitumen (PMB). Rheological properties are measured using Rotational Viscometer, Dynamic Shear Rheometer and Bending Beam Rheometer at grade-specific testing temperatures. A neat bitumen PG64-22 and two PMB PG70-22 and 76-22 in un-aged (original) and aged conditions were tested at two temperatures: 143 °C and 185 °C for 1/2, 2 and 4 h. The effect of short-term aging by rolling thin film oven was also investigated. To investigate the rheological properties over a wide range of temperatures, temperature sweep testing was conducted from 35 °C to 110 °C at a 10 rad/s frequency. The results suggest that there was no significant difference in the viscosity, complex modulus and creep stiffness for the tested bitumen. The RTFO aging index, absolute drop of complex viscosity and temperature aging indices were used to evaluate the bitumen preparation settings. The study recommends using the 143 °C and 2-h heating for proper preparation prior to standard lab testing. The study also investigated the aging influence in rheological properties for neat and PMB using the black diagram, DSR function map, and critical-stiffness temperature.     

Effect of wax on basic and rheological properties of bitumen with similar Penetration-grades

This paper presents the results of a study on the wax content, the basic and rheological properties of seven unmodified bitumens with Penetration-grades 60–70 and the effect of wax on these bitumens. Among the bitumens, one (currently used in Hong Kong) was supplied by a manufacturer in Singapore while the other six bitumens were obtained from manufacturers in Mainland China. The results of the basic tests show that all bitumens are Penetration-grade 60–70 and have similar basic properties. The test results comply with the Hong Kong bitumen specification. However, the wax contents of some of the bitumens manufactured from crude oil deposited in China are relatively high. The test results obtained by the dynamic shear rheometer further indicate that the bitumens with low wax content performed better than those with high wax content under a high temperature environment. The test results exhibit relatively good correlation between the wax contents and the rheological properties of the bitumens. Therefore, standards and procedures should be established in Hong Kong to specify requirements on wax content or Performance-grade for bitumen used in road paving.     

Effect of ageing on bitumen chemistry and rheology

Effect of ageing on bitumen chemistry and rheology was studied. Seven bitumens were aged according to the thin film oven test (TFOT) and the rolling thin film oven test (RTFOT). The binders were characterised using infrared spectroscopy, chromatography and dynamic mechanical analysis. Statistical correlation between different chemical parameters, as well as between chemical and rheological parameters, was examined. The relationship between TFOT and RTFOT was also investigated. It was observed that ageing influenced bitumen chemistry and rheology significantly. However, chemical and rheological changes were generally not consistent, and consequently, ageing susceptibility of bitumens may be ranked differently when different evaluation methods are used. Regardless of the type of the parameters measured, a strong correlation was observed between TFOT and RTFOT, and the two ageing procedures show similar severity.     

Effects of nanoclay on rheological properties of bitumen binder

Nanoclays are the new generation of processed clays of interest in a wide range of high performance composites. In other words, nanoclay is defined as clay that can be modified to make the clay complexes compatible with organic monomers and polymers. Here, it can be said that the polymeric nanocomposites are among the most exciting and promising classes of materials discovered recently. A number of physical properties can be enhanced successfully when as a polymer is modified with small amount of nanoclay on condition that the clay is dispersed at nanoscopic level. This research has accomplished a comparative rheological test on the unmodified and nanoclay modified bitumen. For that matter, so, two types of nanoclay were used: nanofil-15 and cloisite-15A. The nanostructure exfoliation of nanoclay platelets in bitumen has been studied using X-ray diffraction (XRD). In the present research, although the empirical rheological test on bitumen are penetration, softening point, ductility and ageing effect, the fundamental rheological test by dynamic shear rheometer (DSR) is conducted on modified and unmodified bitumen. Test results show that while nanoclay changes rheological properties of bitumen and increases stiffness, it also decreases angle phase and improves ageing resistances, as well.     

Effect of bitumen wax on asphalt mixture performance

This paper mainly deals with waxes which are naturally present in bitumens, and does not include synthetic waxes that sometimes are proposed as bitumen additives. The main objectives were to study the rheological effect of bitumen waxes and the impact of waxy bitumens on asphalt mixture performance, such as rutting, low temperature cracking, and water sensitivity. In the rheological characterisation of bitumens, a dynamic shear rheometer (DSR) and bending beam rheometer (BBR), as well as various conventional methods, were used. For asphalt mixtures, rutting, low temperature cracking and water sensitivity were evaluated by wheel tracking test (WTT), thermal stress restrained specimen test (TSRST), and modified Lottman test, respectively. It was found that, at high service temperatures and within the same bitumen grade, differences in rutting between the asphalt mixtures made with waxy and non-waxy bitumens were relatively small. However, the presence of wax in bitumen resulted in physical hardening at low temperatures. Using waxy bitumens, asphalt mixtures tended to show higher fracture temperature. As regards water sensitivity, no effect of the wax content in bitumen was seen. The water sensitivity was however heavily influenced by type of aggregate and to less extent by bitumen type. The present study implies that the effect of wax on bitumen quality and asphalt mixture performance depends on many factors. Those may include the chemical composition of the bitumen and particularly the nature of the wax.     

二氧化锰对超轻泡沫混凝土物理力学性能的影响

为了提高双氧水分解反应速度和效率,采用MnO_2作为双氧水的催化剂,研究MnO_2催化剂对超轻泡沫混凝土吸水率、干密度和抗压强度的影响。试验结果表明,MnO_2用量为双氧水用量0.05%时,催化剂对超轻泡沫混凝土的吸水率、干密度和抗压强度影响较小;当MnO_2用量增加到双氧水用量的0.1%~0.2%时,超轻泡沫混凝土吸水率和干密度明显下降,但抗压强度反而有所增大;当MnO_2用量超过双氧水用量的0.3%后,对超轻泡沫混凝土的物理力学性能产生了明显不利的影响。采用双氧水作为发泡剂时,MnO_2的适宜用量为双氧水质量的0.1%~0.2%。     

Preparation and properties of bitumen modified by EVA graft copolymer

This paper presents a laboratory study of modified bitumen containing ethylene vinyl acetate (EVA) and ethylene vinyl acetate grafted maleic anhydride (EVA-g-MAH) copolymers. When the different polymers were added, the physical properties of modified bitumens, such as softening point, ductility at low temperature and storage stability at high temperature are changed. The polymer modified bitumens (PMBs) were analyzed by thermogravimetry (TG), derivative thermogravimetry (DTG) and fourier transform infrared spectroscopy (FTIR). Thermal characterizations showed that the main decomposition stage refers to samples with modifiers exhibited a slight increase in thermal stability and the sample with the highest stability was EVA-g-MAH PMBs. FTIR analysis suggested that it is difficult to prove the EVA-g-MAH has reacted with the functional group in bitumen by FTIR spectrum. The dynamic shear rheometer (DSR) tests reported that added content of EVA-g-MAH has great effect on the rheological properties of the binder and its high temperature performance was improved while its temperature susceptibility was reduced in compare to EVA modified bitumens binder.     

Effect of filler on low temperature physical hardening of bitumen

Laboratory investigations of low temperature physical hardening of bitumen using a Bending Beam Rheometer (BBR) are described. The study encompasses five bitumens, three conditions with regard to additives and three testing temperatures (−15, −25 and −30°C). As additives, two fillers, hydrated lime and calcium carbonate, were used. The effect of the fillers on the isothermal low temperature hardening was evaluated with the aid of a physical hardening index. The viscoelastic nature of the bitumens and bitumen/filler mixtures was investigated utilising the Burger model, and the Burger parameters were used to calculate dissipation energy ratios (dissipated energy over stored energy) in each BBR test. The results obtained did not indicate any significant effect of the fillers on low temperature physical hardening. Analyses of the dissipation energy ratio showed a considerable capacity for energy dissipation, even at a temperature as low as −30°C. With few exceptions, more energy was dissipated than stored during a BBR test. It appears that the dissipation energy ratio is not necessarily related to the stiffness of the binder.     

改性沥青的流变性和储存稳定性研究

以高富AH-50为基质沥青分别制备SBS、胶粉和EVA改性沥青,利用动态剪切流变仪(DSR)分析不同种类改性沥青动态黏弹参数(储存模量G'和损失模量G″)随频率和温度的变化,结合60℃稳态流动试验和Carreau模型表征沥青的流变性能,并用储存稳定指数IS表征不同改性剂与沥青的相容性能。结果表明:试验范围内,随频率的增加G'和G″逐渐变大,相同频率下G'明显小于G″,改性沥青以黏性成分为主,且两者的差值在低频和高温下较大;与基质沥青相比,SBS和胶粉改性沥青的临界剪切速率γc降低幅度远大于EVA改性沥青的γc,SBS和胶粉的掺加使沥青偏离牛顿流体的程度更大,对剪切的敏感性更高;SBS和胶粉与沥青的相容性较差,在相分离时SBS迁移至上段,胶粉迁移至下段,而EVA与沥青的相容性较好,体系不易发生相分离。     

Rheological properties and storage stability of bitumen/SBS/montmorillonite composites

Styrene–Butadiene–Styrene triblock copolymer is commonly used for modifying physical, mechanical and rheological properties of bitumen. Because of the poor compatibility between SBS and bitumen, SBS modified bitumen is not storage stable at high temperature. To obtain more compatibility between SBS and bitumen, several methods have been suggested. In this study, organophilic montmorillonite/SBS modified bitumen mixtures were prepared by melt intercalated blending. Physical and rheological properties of polymer modified bitumen were compared before and after adding nanoclay to the bitumen. Results showed that the presence of nanoclay improves the storage stability of PMB significantly without adverse effect on other properties of it. The structure of OMMT/SBS/bitumen blend was characterized by XRD. The spectra indicated that proper dispersion of OMMT in SBS led to a homogenous blend which is named exfoliated structure. The result of storage stability test showed that the difference in softening point was in good accordance with ASTM standard limitation which means that OMMT can improve the storage stability of PMB. Also morphological analysis confirmed storage stability results.