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。     

Characterization of rutting resistance of EBS-modified asphalt mixtures

Driven by Kyoto protocol to reduce the gas emission, warm mix asphalt (WMA) as an alternative of hot mix asphalt has gained huge interest among researchers. Despite many advantages, rutting resistance of WMAs is always questionable. In this study, ethylene bis(stearamide) (EBS) was used as a wax-based additive to produce WMAs. Samples were produced at three different compaction temperatures. To evaluate rutting resistance of mixtures, all cylindrical specimens were tested by dynamic creep and dynamic modulus tests at various compaction temperatures. Results indicate that rutting resistance of EBS-modified samples are remarkable, especially when compaction temperature is low.     

Modelling the complex modulus strain relationship of asphalt binders

The authors present the results and analysis of amplitude sweep tests done on 10 different asphalt binders using dynamic shear rheometer. The test was done from 30 to 70°C using a spindle geometry of 25 mm diameter with 1 mm gap setting. Matching function concept coupled with a three stage optimization procedure has been used to propose a new model for evaluating the complex modulus of bitumen at any given temperature and strain level. The model has been validated and is found to be fairly accurate for different types of binders.     

Investigate the physical and rheological properties of asphalt binders modified with barium sulfate nanoparticles

Abstract

The aim of this study is to investigate the physical and rheological properties of modified asphalt binders with barium sulfate (BaSO₄) nanoparticles. The penetration grade test and the softening point test on the controlled and modified asphalt binders showed that the presence of nanoparticles improved the physical properties of asphalt binders. Dynamic shear rheometer (DSR) test was performed on the main and modified asphalt binders in unaged and short-term aged modes. The asphalt binders containing 2% of nanoparticles in each of the unaged and short-term aged modes have the maximum value of rutting parameter at all temperatures.     

Viscoelastic fatigue resistance of asphalt binders modified with crumb rubber and styrene butadiene polymer

In the present research study, the fatigue behavior of modified asphalt with crumb rubber (CR) and styrene-butadiene-styrene (SBS) are investigated. Each of these additives was mixed with a 85–100 neat bitumen at two different dosages. The time sweep test was used to investigate the viscoelastic fatigue properties of asphalt binders in terms of energy dissipation. Linear amplitude sweep tests were conducted to study the fatigue life of asphalt binders under varying loads based on the concepts of viscoelastic continuum damage mechanics. Results showed that adding CR and SBS can enhance the fatigue resistance of modified asphalts based on the energy approach and viscoelastic continuum damage analysis.     

Laboratory evaluation of the effect of waste plastic bottle (PET) on rutting performance of hot mix asphalt mixtures

The authors aim to evaluate the effects of using waste polyethylene terephthalate (PET) as a modifier on properties of asphalt mixtures. The rutting performance of asphalt mixtures that include various percentages of PET (0%, 0.25%, 0.5%, 0.75%, 1%) and various PET sizes (10 × 2.5, 20 × 2.5, and 30 × 2.5 mm) were evaluated through dynamic creep test and Hamburg wheel tracking device. Results indicated that the rutting resistance of mixtures increases by addition of PET contents and decreases with increase in PET sizes.     

Laboratory evaluation of rutting performance of cold recycling asphalt mixtures containing SBS modified asphalt emulsion

Because limited researches have been conducted to investigate the effect of additives on recycled asphalt mixture properties, in this research, cement and lime were used as additives in cold in-place recycling mixtures containing SBS emulsion asphalt. In this research study several experiments such as Marshall stability, dynamic creep, and wheel tests were conducted. Results indicated that SBS, cement, and lime increase Marshall stability, and resistance to permanent deformation.     

Laboratory evaluation of the effect of reclaimed asphalt pavement on rutting performance of rubberized asphalt mixtures

The utilization of crumb rubber and reclaimed asphalt pavement (RAP) has proven to be economical, environmentally sound, and effective in increasing the performance properties of the asphalt mixtures. In this research study the RAP content was varied from 0–60% (0%, 20%, 40%, and 60%) and crumb-rubber additive (0%, 10%, and 15% by weigh of bitumen) was blended with the unmodified binder by using wet process. The rutting performance of these modified asphalt mixtures were investigated. The results of the experiments indicated that the use of RAP and crumb rubber in HMA can effectively improve the engineering properties of these mixes.     

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.     

Laboratory investigation of rutting performance of warm mix asphalt containing high content of reclaimed asphalt pavement

In this research, the influence of warm mix additives on the properties of warm-mix asphalt (WMA) containing recycled asphalt pavement (RAP) was investigated and compared with the same graded hot-mix asphalt (HMA). WMA mixtures were produced using Sasobit and Zycotherm as organic and chemical WMA additives, respectively. Mixtures were prepared containing RAP in different proportions (0%, 25%, 50% and 75 % of total aggregates). Dynamic creep and wheel track tests were used to investigate the resistance of specimens to permanent deformation. Zycothem WMA mixtures showed less resilient modulus and rutting resistance than Sasobit WMA mixtures. It was also concluded that increasing the amount of RAP in mixtures improves resilient modulus and rutting resistance of all mixtures.     

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.     

Effects of nanoclay on hot mix asphalt performance

The purpose of this study was to evaluate of nanoclay effects as an additive on performance of asphalt mixtures. Two types of montmorillonite nanoclay, namely CA and CB, were used at concentrations of 2%, 4%, and 6%. Marshall, indirect tensile strength, resilient modulus, and dynamic creep tests were performed to investigate the effect of additives on moisture susceptibility, structural response, and rutting resistance. The results showed improvement of the asphalt mixture performance by adding nanoclay with respect to all tests. According to the results, samples containing nanoclay CA have better performance in comparison with the samples containing CB.     

A statistical analysis on the mechanical properties of nanocomposite modified asphalt mixtures

This study aimed to characterize the rate of change that takes place in the mechanical properties of polymer-nanocomposite asphalt (PNMA) mixtures due to altering asphalt binder grade and styrene-butadiene-styrene (SBS) type. Laboratory testing program included Marshall stability, resilient modulus, and wheel-tracking tests. Test results were compared and analyzed statistically by means of two-way analysis of variance and Tukey test. Variance analysis indicated the significant effect of both binder type and SBS grade on mechanical properties of asphalt mixtures. Interaction between binder type and SBS grade is also meaningful in all the experiments. The results also show that the binder type is the primary affecting factor, followed by the SBS grade.     

Experimental study on the effect of nanosized carbon particles on fatigue resistance of asphalt binders

The present research study investigates the fatigue resistance of asphalt binders modified with carbon nanoparticles. Three different modified bitumens containing three different dosages of carbon nanoparticles were tested to capture fatigue properties under the concept of viscoelastic continuum damage mechanics through frequency sweep and linear amplitude sweep tests. Results show that adding carbon nanoparticles can enhance the fatigue life of neat asphalt binders.     

Laboratory evaluation of the effect of bentonite on performance of bitumen and hot mix asphalt mixtures

In this research study, bentonite additive was used to modify original binder (60–70 penetration grade). The experimental program included use of five percentages of bentonite (10%, 15%, 20%, 25%, and 30%) by weight of bitumen. Physical properties of modified and unmodified bitumen were evaluated through penetration grade, softening point, ductility, and temperature susceptibility tests. The performance characteristics of mixtures were determined through indirect tensile strength, resilient modulus, and moisture susceptibility tests. The results demonstrate that addition of bentonite improves Marshall stability, tensile strength, and resilient modulus of mixtures, but led to decrease the resistance to moisture damage.     

不同标号沥青的流变性能

借助温度扫描、频率扫描、多重应力蠕变恢复等实验,对20号、30号、50号、70号沥青及其旋转薄膜烘箱老化后沥青的流变性能进行了评价。结果表明：随着温度升高,4种沥青老化前后复数剪切模量和车辙因子均降低,并且老化后的高于老化前;在60℃温度下,无论是在低频还是高频荷载作用下,标号越低,沥青耐剪切变形能力越强,耐车辙性越好,而应力敏感性降低;标号越低的沥青,G-R参数值越大,耐开裂性则降低。     

Comparisons with high viscosity additive effects on base and modified asphalt

In this research, three types of high viscosity additives with different volumes were added to both 70# base asphalt and SBS modified asphalt, the dynamic viscosity and high temperature performance tests were conducted. The results show that with the same volume and type of the additive, SBS modified asphalt has a much higher dynamic viscosity and high temperature grade than those of the base asphalt. When the volume of each additive type increases from 0% to 12%, the dynamic viscosity would increase in a different trend, which could be described as three stages with different increasing speeds, and the variability and the demarcation point of the adjacent two stages depend on the asphalt modification, additive type and the volume. With regard to the high temperature grade, it was found that the effect of different additive types on high temperature performance should be separated from asphalt modification.     

Warm asphalt mixtures produced with addition of CCBit

There is a growing concern with the environmental damage caused by the various types of industrial activities. Because of that, research in paving has sought alternatives to reduce fuel consumption and emissions of greenhouse gases generated by those. The warm mixtures have received increasing attention because they are capable of decreasing the mixture and compaction temperatures of asphalt mixtures. The objective of this study was to evaluate the effect of the incorporation of CCBit from the mechanical characterization of asphalt mixtures. From the results, it was found that the incorporation of CCBit has the advantage of reducing mixing and compaction temperatures without harming their mechanical behavior.     

乳化沥青冷再生混合料初期性能评价

废旧沥青混合料的乳化沥青冷再生技术是路面养护和维修的重要措施。由于乳化沥青在冷再生混合料成型初期提供的粘结力较低，使人们担心会发生松散破坏。为此提出对乳化沥青冷再生混合料增加初期性能的评价。用肯塔堡飞散试验评价其初期抗松散性，用修正的冻融劈裂试验分析成型过程中水对其初期路用性能的影响。最后对使用哈一同公路维修旧料所设计的乳化沥青冷再生混合料的初期性能进行检验。发现采用该方法能够区分和评价乳化沥青冷再生混合料的初期性能，可以作为这种混合料性能检验的一个方法。     

改性沥青抗变形能力研究

以测力延度（温度为5℃,拉速为5 cm/min）及15℃的弹性恢复对基质沥青及其不同SBS加入量的改性沥青进行抗变形能力的评价,通过对测力延度曲线的分析,探索基质沥青及SBS改性沥青拉伸过程中的规律,研究改性沥青抗变形能力。