PHYSICAL PROPERTIES OF ASPHALT-RUBBER BINDER

This study was performed to determine how the rheological properties of asphalt-rubber binders are affected by various parameters. Properties studied were asphalt composition, rubber dissolution, and the low-, intermediate-, and high-temperature rheological properties, measured with the bending beam rheometer. dynamic shear rheometer, and rotational viscometer, respectively. The rheological properties of the asphalt-rubber binder were determined to be dependent on the rubber content (weight percent), rubber particle size, and base asphalt composition. By controlling these variables, an asphalt-rubber binder with improved low-temperature cracking resistance, improved mid-temperature rutting resistance and temperature susceptibility, and a non-detrimental high-temperature compaction viscosity, all relative to the base asphalt, can be produced.     

Characterization of ductility of field-aged petroleum asphalt

This study evaluated the ductility properties of sixty-nine different types of asphalt extracted from the field projects using dynamic shear rheometer (DSR) monotonic and oscillation test. These extracted asphalts were subjected to field aging. The ductility of asphalt mixture was also characterized by indirect tensile test. It was found that test temperature had effect on property measurement. Failure strain measured at 5°C from monotonic test correlated well with DSR function measured from oscillation test. Both higher failure strain and lower DSR function indicated a better ductility of asphalt, and were also indicative of ductility of asphalt mixture. Failure strain would be potentially used to separate polymer-modified asphalt from non-polymer-modified asphalt.     

PHYSICAL PROPERTIES OF ASPHALT-RUBBER BINDER

ABSTRACT

This study was performed to determine how the rheological properties of asphalt-rubber binders are affected by various parameters. Properties studied were asphalt composition, rubber dissolution, and the low-, intermediate-, and high-temperature rheological properties, measured with the bending beam rheometer. dynamic shear rheometer, and rotational viscometer, respectively. The rheological properties of the asphalt-rubber binder were determined to be dependent on the rubber content (weight percent), rubber particle size, and base asphalt composition. By controlling these variables, an asphalt-rubber binder with improved low-temperature cracking resistance, improved mid-temperature rutting resistance and temperature susceptibility, and a non-detrimental high-temperature compaction viscosity, all relative to the base asphalt, can be produced.     

橡胶沥青的动态剪切流变试验分析

通过动态剪切流变试验,对路用橡胶沥青结合料的流变性能进行了分析。试验采用2种不同类型的基质沥青以及4种不同含量的胶粉制备成5种不同类型的橡胶改性沥青,使用动态剪切流变仪分别对原样、短期老化以及长期老化三种状态的试样进行了测试,分析了各粘弹性参数随橡胶沥青类型变化的规律。同时也对比分析了各种类型的胶粉改性沥青的高温抗车辙性能和抗疲劳性能。试验结果表明,橡胶胶粉含量在15%～21%范围内时,橡胶沥青的高温和中等温度下疲劳性能均随橡胶胶粉含量的增加而提高。     

Thermal and rheological properties of nanoparticle modified asphalt binder at low and intermediate temperature range

There is a paucity of knowledge regarding the effect of nanoparticles on the performance of asphalt binder against fatigue and low-temperature cracking. In this research, asphalt binders were modified using SiO₂, TiO₂, and CaCO₃ nanoparticles, and rheological and thermal properties of the modified binders were investigated. Differential scanning calorimetry was used to determine glass transition temperature, and rheological properties at low and intermediate temperatures were determined using bending beam and dynamic shear rheometers, respectively. The results suggested that the addition of these nanoparticles increases glass transition temperature and the low-temperature stiffness of asphalt binder. Furthermore, increase in complex shear modulus and decrease in phase angle values were observed at intermediate temperatures. It can be concluded that inferior performance at low and intermediate temperature is expected by the addition of nanoparticles to asphalt binder.     

Rheological properties of Deurex – modified WMA binder containing SBS

Recently, warm mixture asphalt (WMA) technologies drawn much attention for their benefits to environment and workability. Deurex is novel type of warm mixture asphalt additive, which is extracted from sugar cane. The objective of this study is to experimentally investigate the effect of Deurex on SBS modified asphalt. The Deurex was blended into SBS modified asphalt at the dosages of 2%, 3% and 4%. Physical properties tests including penetration, soft point and ductility, dynamic shear rheometer (DSR), and bending beam rheometer (BBR) tests were carried out. The test results showed that the increase in Deurex additive could significantly reduce the viscosity of SBS modified asphalt, which indicates that the Deurex can serve as an effective type of warm mixture asphalt additive. In addition, the results showed that the addition of Deurex can enhance the high temperature properties while lower the low temperature performance of SBS modified asphalt. However, as long as the Deurex dosage is not higher than 3%, the low temperature grade of WMA binder keep the same as the control binder.     

Properties of asphalt binder and asphalt concrete containing waste polyethylene

In this study, the effects of addition of waste polyethylene on asphalt binder and asphalt concrete mixture properties were studied. Four asphalt concrete mixtures (each mixture containing different percentages of shredded polyethylene material) were prepared and tested as per Indian specifications. Shredded polyethylene and hot asphalt binder were added to heated aggregate (in same sequence) until all aggregates were coated. The loose mixtures were compacted and tested for its mechanical and volumetric properties. Furthermore, compacted specimens were aged for short- and long-term conditions. The extracted binder from the aged and control mixtures was tested for its rheological properties using a dynamic shear rheometer. Mixtures containing shredded polyethylene showed improvement with respect to the Marshall strength, flow, and volumetric properties. The properties of recovered asphalt binder indicated that the addition of polyethylene improved complex modulus values and decreased phase angle values over range of frequencies.     

High-temperature performance of gilsonite-modified asphalt binder and asphalt concrete

This article investigates the effect of addition of gilsonite (natural bitumen) to asphalt binder on its rheological behavior at high temperatures through construction of complex modulus (G*) master curve using dynamic shear rheometer (DSR) test. This impact is further investigated by evaluation of performance of asphalt concrete modified with gilsonite at elevated temperatures using repeated dynamic creep test. The results showed that introduction of gilsonite to asphalt binder increases its stiffness and elasticity. Also, the results indicated that the modification of asphalt concrete with gilsonite improved rutting resistance significantly.     

Effect of chlorination on the assessment of waste engine oil modified asphalt binders

The main objective of this study is to develop a new asphalt binder using waste engine oil (WEO) and improve its properties especially the resistance to rutting, reduces thermal susceptibility as well as the solubility in kerosene. The properties of WEO binders were modified further by chlorine. All blends were evaluated using Fourier transform infrared (FT–IR) spectroscopy, Thermal gravimetric analysis (TGA) differential scanning calorimetry (DSC) and dynamic shear rheometer (DSR). Asphalt binder specimens containing different concentrations (0, 2, 4, 6, and 8) % of waste engine oil with and without chlorine gas were fabricated.     

按PG性能等级规范评价国产重交通道路沥青的性能

简单介绍了新修订的PG性能等级规范由不同温度下的弯曲梁流变试验和直接拉伸试验数据得到临界开裂温度，进而确定沥青胶结料低温性能等级的方法，按照新规范规定的指标要求，对两种国产重交通道路沥青的性能进行了评价，结果表明，它们具有优良的高温稳定性，低温抗裂性和抗疲劳性能，同原规范相比，新规范在评价沥青胶结料的低温性能方面具有更好的科学性。     

国产沥青抗裂性能的研究

为了探求国产沥青的抗疲劳性能和低温抗裂性能，运用SHRP试验方法中的动态剪切流变仪(DSR)、弯曲梁流变仪(BBR)分别对三种国产沥青的RTFOT／PAV残留物的流变特性进行了试验研究，结果表明，在较宽的温度域范围内，经历过RTFOT／PAV老化的沥青试样的复数剪切模量G^*、相位角δ、疲劳开裂因子G^* sinδ、蠕变劲度S及m值与试验温度丁之间存在着良好的相关性。     

SBR改性沥青的低温性能评价

主要对三种国产基质沥青和六种丁苯橡胶(SBR)改性沥青进行了测力延度试验(FDT)、常规技术指标试验以及SHRP的动态剪切仪(DSR)和弯曲梁流变仪(BBR)试验，并且将FDT中采用的粘弹比、拉伸柔度、应变能等指标与沥青的当量脆点(T1．2)、以及损失模量、弯曲劲度模量(S)、斜率(m)相比较，结果显示FDT所选的三个评价指标与SHRP的评价指标有良好的相关性，从而说明了采用FDT对沥青结合料在老化、疲劳综合作用下的低温性能进行评价的经济合理性以及选择三个评价指标的可靠性。     

Effect of nanoclay on performance of neat and SBS-modified bitumen and HMA

The aim of this research was to investigate impact of nanoclay on rutting and moisture damages resistance of neat and SBS-modified asphalt binder and mixture. 4% SBS was blended with 2% nanoclay and 6% nanoclay was used and compared with neat and 4% SBS-modified asphalt binder and mixes. Results of performing rotational viscosity, dynamic shear rheometer, repeated creep recovery, indirect tensile strength, and dynamic creep tests indicated nanoclay has positive impact on rutting and moisture damages resistance of neat and modified asphalt binder.     

A Study on the Performance and Storage Stability of Crumb Rubber-Modified Asphalts

Abstract

Crumb rubber–modified asphalt (CRMA) with good storage stability was prepared using activated crumb rubber. The activation of crumb rubber was carried out by blending crumb rubber with polymeric compatibilizer in extruder to improve interaction between crumb rubber and asphalt. The softening point difference (SPD) and photomicrographs were used to reveal the storage stability of CRMA. The long-term storage stability test results indicate that the softening point difference of CRMA was below 2.5°C. The rheological characteristics of the binders were studied with a dynamic shear rheometer (DSR) and a bending beam rheometer (BBR). The results showed that the CRMA binders are possessed of the better resistance to permanent deformation at high temperature and cracking at low temperature than those SBS-modified and straight-run asphalts.     

沥青软化点温度下的粘弹特征

本文对30余个沥青样品进行了动态剪切扫描试验,探讨了软化点环境下的沥青的粘弹性状态。试验发现：在软化点温度条件下,纯沥青与改性沥青处于两种不同的流变状态,石油沥青粘弹组成中粘性分量居多,相位角多在80o以上;而SBS改性沥青则保持较低的模量值和相位角,弹性仍保持为一个明显的特质。同时,利用Shapiro-Wilk正态检验发现,在a=0.05置信水平下,不管老化状态如何,纯沥青软化点对应一个稳定的复数模量,在荷载100Pa、频率10rad/s的实验条件下,该模量均值为13033.7Pa,标准差为2104.7Pa。并利用这种等模量规律求取纯沥青的软化点,证明了与实测软化点的良好关联性。需要更多数据以验证本文的初步结论。     

A Study on Xinjiang Asphaltite as an Asphalt Modifier. Part II: Rheological Evaluation of Modified Asphalt Binders

Modified asphalt binders with varying Xinjiang asphaltite contents between 4% and 16% were prepared in laboratory. Dynamic shear rheometer temperature sweep and time sweep tests, bending beam rheometer tests, some conventional tests including penetration and softening point were performed to analyze the rheological properties of these asphalt binders and evaluate Xinjiang asphaltite potential as asphalt modifier. Test results showed with the Xinjiang asphaltite content increasing, complex shear modulus increased and phase angle decreased, which indicated Xinjiang asphaltite could improve the elasticity and deformation resisting of binders. Fatigue failure life of asphalt binders grew exponentially with Xinjiang asphaltite content. Moreover, Xinjiang asphaltite had an adverse effect on the low temperature performances of asphalt binders based on measured creep stiffness and m-value. Based on these test results modification mechanism of Xinjiang asphaltite was analyzed. It is thus suggested that Xinjiang asphaltite is better suitable as a high temperature resistant and anti-fatigue asphalt modifier material.     

Investigation of the effects of recycled engine oil bottoms on asphalt field performance following an oxidation modeling approach

This work investigates the effects of recycled engine oil bottoms (REOBs) on asphalt field performance by comparing asphalts with and without REOBs in terms of the asphalt properties required for pavement oxidation modeling. Specifically, oxidation reaction kinetics parameters, dynamic shear rheometer (DSR) function (DSRFn) hardening susceptibility (HS), and low sheer viscosity (LSV) HS are determined and compared for base binder, 5 wt.% REOBs, and 15 wt.% REOBs blends. At the higher percentage, addition of REOBs appears to increase the initial oxidation rate at field temperatures and significantly increases LSV HS, but does not significantly increase the DSRFn HS. A field modeling example elucidates the effects.     

Experimental investigation of the effect of asphalt binder modified with nanosilica on the rutting,fatigue and performance grade

This research was performed to investigate the effect of nano-silica on the asphalt binder performance grade, rutting, and fatigue. The rutting and fatigue performance was tested by Multiple Stress Creep and Recover (MSCR) and time sweep test. The low-temperature cracking was tested by Bending Beam Rheometer test (BBR). The results showed the good performance of nano-silica in high and intermediate temperatures. The results of MSCR test show better performance in rutting and recovery as a result of the elastomeric property of nano-silica even in high temperatures. Nano-silica had a negative effect on the low performance grade of asphalt binder. The addition of nano-silica to asphalt binder increased the fatigue life up to 2.8 times. The Fourier transform infrared spectroscopy (FTIR) analysis was used for chemical analysis.     

An investigation on the effect of SBS+Vacuum bottoms residue modification on rheological characteristics of asphalt binder

In this research, the effect of adding SBS and vacuum bottoms residue on 60/70 neat asphalt binder have been carried out using classic and superpave testing methods. Adding SBS led to increase of softening point, elastic recovery and viscosity of asphalt binder. Besides, SBS reduced the penetration and ductility of specimens. Results of dynamic shear rheometer indicated that G^* and G^*sinδ reduced by adding the SBS content before and after aging while δ and G^*/sinδ parameters increased. Therefore, adding SBS improves the permanent deformation and fatigue resistance of neat asphalt binder.     

Properties of asphalt modified with devulcanized polyethylene terephthalate

The objective of this research is to investigate the effectiveness of the devulcanized polyethylene terephthalate in enhancing the performance characteristics of modified asphalt binders. The physical and rheological behavior of four binder samples were investigated using the penetration, softening point, storage stability, rotational viscometer, and dynamic shear rheometer tests. The polymer tends to decrease penetration and increase softening point, viscosity, and permanent deformation resistance of modified binders in comparison with base asphalt binders. However, this processed polymer could not be considered storage stable blend at high temperatures.