Effects of recycled asphalt pavements on the fatigue life of asphalt under different strain levels and loading frequencies

Fatigue lives of Hot Mix Asphalt (HMA) and binder have been studied separately for a long time. However, fatigue lives of HMA containing Recycled Asphalt Pavement (RAP) and the binder extracted from the same HMA containing RAP have not been studied yet. This study examines the effects of RAP, loading frequency and strain level on the fatigue lives of asphalt mixtures and binders. In addition, the relationship between the fatigue lives of asphalt mixture and binder is determined. Beam fatigue tests were conducted to determine the fatigue behaviors of two asphalt mixtures: one with 35% RAP and the other without RAP. To evaluate binder’s fatigue behavior, binders were extracted and recovered from these two mixtures. Then, fatigue lives of these two binders were determined using time sweep and Linear Amplitude Sweep (LAS) tests. Results show that presence of RAP in mixture causes a decrease in the mixture’s fatigue life, whereas it causes an increase in the fatigue life of binder. As expected, an increase in loading frequency results in an increase in the fatigue lives of asphalt mixture as well as binder. In addition, increase in strain level causes a decrease in the fatigue lives of both mixtures and binders. Fatigue lives of binders from time sweep and LAS tests show a good correlation with the mixture’s fatigue life by the beam fatigue test.     

两种沥青胶浆的疲劳及自愈合性能试验

为了研究沥青胶浆的疲劳及自愈合特性,利用动态剪切流变仪（DSR）进行时间扫描及疲劳-愈合-再疲劳测试,并通过原子力显微镜（AFM）对细观结构进行观测,比较分析了不同粉胶比下基质沥青胶浆和苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）改性沥青胶浆的疲劳性能,以及在常温（25℃）下3个不同间歇期的自愈合性能。试验发现：SBS沥青胶浆具有更好的疲劳和自愈合性能,两种沥青胶浆疲劳寿命均随粉胶比的增大而增加,同一粉胶比条件下,更长的间歇期有利于其自愈合,过大或者过小的粉胶比都会降低沥青胶浆的自愈合性能;AFM观测结果表明：基质沥青胶浆出现明显的"蜂状结构",粉胶比增加,矿粉吸附更多的沥青质,"蜂状结构"变多,与沥青界面内聚力作用增强,提高了抗疲劳性能,SBS改性剂与沥青相容性良好,改性沥青胶浆没有出现"蜂状结构",改性剂的加入增强了分子间内聚力,有助于提高抗疲劳性能,因此建议路面材料选用改性沥青胶浆。     

Dynamic mechanical characterization of asphalt concrete mixes with modified asphalt binders

The primary objective of this work is to characterize and compare the dynamic mechanical behavior of asphalt concrete mixes with styrene butadiene styrene (SBS) polymer and crumb rubber modified asphalt binders with the behavior of mixes with unmodified viscosity grade asphalt binders. Asphalt binders are characterized for their physical and rheological properties. Simple performance tests like dynamic modulus, dynamic and static creep tests are carried out at varying temperatures and time. Dynamic modulus master curves constructed using numerical optimization technique is used to explain the time and temperature dependency of modified and unmodified asphalt binder mixes. Creep parameters estimated through regression analysis explained the permanent deformation characteristics of asphalt concrete mixes. From the dynamic mechanical characterization studies, it is found that asphalt concrete mixes with SBS polymer modified asphalt binder showed significantly higher values of dynamic modulus and reduced rate of deformation at higher temperatures when compared to asphalt concrete mixes with crumb rubber and unmodified asphalt binders. From the concept of energy dissipation, it is found that SBS polymer modification substantially reduces the energy loss at higher temperatures. Multi-factorial analysis of variance carried out using generalized liner model showed that temperature, frequency and asphalt binder type significant influences the mechanical response of asphalt concrete mixes. The mechanical response of SBS polymer modified asphalt binders are significantly correlated with the rutting resistance of asphalt concrete mixes.     

Evaluation and optimization of the engineering properties of polymer-modified asphalt

Polymers are increasingly being used to modify asphalt and enhance highway pavement performance. This paper reports the development of a procedure to evaluate and optimize a polymer-modified asphalt (PMA). Two asphalt cements and two styrene-butadiene-styrene (SBS) copolymers were mixed at ten concentration levels. The engineering properties and morphologies of the binders were investigated using a dynamic shear rheometer, scanning electron microscopy (SEM), and other rheological techniques. The morphology of the PMA was characterized by the SBS concentration and the microstructure of the copolymer. Polymer modification increased the elastic responses and dynamic moduli of asphalt binders. As the SBS concentration increased, the copolymer gradually became the dominant phase, accompanied by a change in engineering properties. Results from SEM demonstrated that, up to 6% concentration, good compatibility exists between SBS and asphalt binder. The modified binders show either a continuous asphalt phase with dispersed SBS particles or a continuous polymer phase with dispersed asphalt globules, or two interlocked continuous phases. The optimum SBS content was determined based on the formation of a critical network between asphalt and polymer.     

多聚磷酸与SBS复合改性沥青的改性机制

为研究多聚磷酸(PPA)与苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)复合改性沥青的微观结构和改性机制,对不同掺量(质量分数)的PPA和SBS复合改性沥青样品分别进行了四组分试验、红外光谱试验、荧光显微试验和差示扫描量热试验。结果表明:随着PPA掺量的增加,沥青质含量增多,胶团之间的作用力增强,促使沥青由溶胶结构转变为溶-凝胶结构,提高沥青的黏度;在SBS改性沥青中加入PPA,可增强SBS之间的交联作用及SBS与沥青之间的接枝作用,加强SBS改性沥青的空间网状结构,促使SBS更好地相容于沥青中,改善其高温储存稳定性,并促使SBS分散为细小颗粒,增强溶胀作用,利于SBS发挥改性效果;在低SBS掺量改性沥青中加入PPA,形成的网络结构要优于高SBS掺量单独改性;加入PPA对沥青的玻璃化转变温度没有明显影响,表明PPA对SBS改性沥青的低温性能影响较小。     

The low temperature properties of conventional and modified asphalt binders evaluated by the failure energy and secant modulus from direct tension tests

In our previous direct tension test (DTT) studies, SBS polymer modification was found to increase the failure stress values with increasing polymer levels. The predicted critical cracking temperatures (T_critical) in Superpave MP la specification were found to be 3 to 6°C lower than the bending beam rheometer (BBR) low temperature parameter according to Superpave MP1 specification. In this study, the DTT results were analyzed and compared in terms of the DTT failure energy and secant modulus instead of failure stress or failure strain values. As expected, the DTT secant modulus was found to increase with increasing hardness of the non-modified asphalt binder materials; however, the secant modulus decreases upon Styrene Butadiene Styrene (SBS) polymer modification. If the secant modulus were used to evaluate the stiffness of asphalt binder materials at low temperature, the SBS modified asphalt binders would not only have better low-temperature properties than predicted by the BBR low-temperature parameter in Superpave MP1 but also better than predicted by the T_critical in Superpave MP1a specification. The failure energy of SBS modified asphalt binder at T_critical was found to be invariably higher than the T_critical failure energy of non-modified asphalt binders, even though the T_critical of PMA was already 3–6°C lower than the T_critical of the non-modified asphalt binder. The elastic polymer network in the PMA probably contributes to higher DTT failure stress, failure strain and failure energy values.     

Modeling and assessment of self-healing and thixotropy properties for modified binders

The fatigue endurance limit of binders is the results of more phenomena (e.g. viscoelasticity, damage, healing, thixotropy, steric hardening) that interact simultaneously making the mechanisms behind the fatigue behavior not properly understood.Currently, there is no consolidated analytical approach inclusive of such phenomena to characterize fatigue performance.This research proposes a criterion to determine the fatigue resistance of binders subjected to monotonous cyclic loading with multiple rest periods. The main rheological properties are measured during each stage using a Dynamic Shear Rheometer and the modeling of their evolution is proposed. The experimental program includes different binders in order to investigate the effects of SBS modification levels and aged binder contents on self-healing potential and fatigue behavior.The proposed criterion enables to identify fundamental contributions leading to a comprehensive fatigue endurance limit. This approach allows different binders to be distinguished taking into account their self-healing capacity and can help to establish a better correlation with in-service performance of mixtures.Moreover, a comparison with a previous analytical approach based on the same kind of test (time sweep) with only one rest period is proposed in order to evaluate the effectiveness and reliability of the proposed criterion. Results show that multiple rest periods are needed in order to fully understand the self-healing and fatigue behavior of bituminous binders and to quantify the contributions given by thixotropy.     

考虑水-温循环的SBS改性沥青复数剪切模量预估模型

为探寻季节性冻土区多次水-温循环后沥青胶结料特征官能团变化与复数剪切模量之间的关系,联合FTIR和动态剪切流变（DSR）试验,对经0、3、6、9、12、15和18次水-温循环后的苯乙烯-丁二烯-苯乙烯嵌段共聚物（SBS）改性沥青进行测试,探明了多次水-温循环下SBS改性沥青复数剪切模量和特征官能团的变化规律;采用灰色关联熵分析理论数学模型,明确了复数剪切模量与特征官能团含量变化的关联程度;基于麦夸特法和通用全局优化算法对不同温度和频率下DSR测试的SBS改性沥青复数剪切模量G*及FTIR测试官能团变化指数进行多元统计回归分析,提出了SBS改性沥青复数剪切模量的预估模型。结果表明:多次水-温循环使沥青发生了水-温老化,但SBS改性剂对沥青水-温老化具有抑制作用;随着水-温循环次数的增加,沥青FTIR图谱中亚砜基与羰基呈现出明显的增大趋势;SBS改性沥青特征官能团变化对复数剪切模量影响程度由大到小的排序为脂肪族化物 > 非对称脂肪族化物 > 芳香族化合物 > SBS含量（苯乙烯+丁二烯） > 亚砜基 > 羰基;多次水-温循环后SBS改性沥青复数剪切模量随着特征官能团含量变化呈现出多元线性关系。      

Performance evaluation of WMA plant and field trial mixes

Warm mix asphalt (WMA) technology is still in its infancy, with significant scope for further exploration of the benefits of incorporation of higher percentages of recycled asphalt RA as well as modified binders for performance enhancement. The objective of this study was to evaluate three different WMA technologies, namely chemical and organic additives as well as foamed technology, within different mix compositions. The variables in mix composition included 10–20 % RA in surfacing mixes and 20–40 % RA in base layer mixes. The binder variables included two base binders, control mixes (no modifier) and ethylene vinyl acetate (EVA) or styrene butadiene styrene (SBS) with or without WMA technologies. A partial factorial experimental design based on the above variables was developed. Full-scale plant mixes and field (construction) mixes were produced and beams were prepared from compacted slabs and tested under 4 point loading to provide master curves and fatigue relations. Comparative results show inconsistent trends between different technologies. control mixes (HMA) can provide both higher and lower flexural stiffness than their WMA counterparts. EVA or SBS modification can provide either superior or inferior mixes to their WMA counterparts depending on the WMA technology. Generally the fatigue results of both the HMA surfacing and base layer mixes at both RA contents are superior to their equivalent WMA counterparts. The implications of these differences are explored in the publication.     

Application of nano-silica and styrene-butadiene-styrene to improve asphalt mixture self healing

Nanoparticles, due to their physical and chemical characteristics, present an inherent potential to improve the performance of bituminous materials. Presently, the technology of producing nanosized particles is evolving, and their application in various aspects of pavement engineering is becoming more cost-effective. Nanosilica, due to its spherical shape, high specific area, very tiny size and higher density compared to bitumen, presents an inherent potential to accelerate molecular randomisation movements, promote bitumen binder flow into microcracks and evolve healing index (HI) of hot mix asphalt (HMA). Moreover, it has been proved that Styrene–Butadiene–Styrene polymer (SBS) promotes fatigue life of HMA and decreases its temperature sensitivity. It would be interesting to know if the addition of nanosilica to modified binder with SBS will promote the total HI and lead to an enhanced HMA life cycle. In this study, the effects of four parameters, most importantly, the effect of the combination of nanosilica particles and SBS polymer to improve the self-healing of asphalt mixture was investigated using the Taguchi design of experiment (DOE) method. Experiments performed with the Superpave indirect tensile test included repeated loadings (fracture) and healing phases. These experiments showed that the combination of nanosilica and SBS promoted the self-healing of HMA, significantly. Moreover, the optimum condition to attain maximum HI and effect factor of each parameter, based on Taguchi DOE method, was obtained. Furthermore, scanning electron microscope images of fatigued, under healing and healed HMA samples were captured to investigate HMA self-healing mechanism.     

Linking asphalt binder fatigue to asphalt mixture fatigue performance using viscoelastic continuum damage modeling

Fatigue cracking is a major form of distress in asphalt pavements. Asphalt binder is the weakest asphalt concrete constituent and, thus, plays a critical role in determining the fatigue resistance of pavements. Therefore, the ability to characterize and model the inherent fatigue performance of an asphalt binder is a necessary first step to design mixtures and pavements that are not susceptible to premature fatigue failure. The simplified viscoelastic continuum damage (S-VECD) model has been used successfully by researchers to predict the damage evolution in asphalt mixtures for various traffic and climatic conditions using limited uniaxial test data. In this study, the S-VECD model, developed for asphalt mixtures, is adapted for asphalt binders tested under cyclic torsion in a dynamic shear rheometer. Derivation of the model framework is presented. The model is verified by producing damage characteristic curves that are both temperature- and loading history-independent based on time sweep tests, given that the effects of plasticity and adhesion loss on the material behavior are minimal. The applicability of the S-VECD model to the accelerated loading that is inherent of the linear amplitude sweep test is demonstrated, which reveals reasonable performance predictions, but with some loss in accuracy compared to time sweep tests due to the confounding effects of nonlinearity imposed by the high strain amplitudes included in the test. The asphalt binder S-VECD model is validated through comparisons to asphalt mixture S-VECD model results derived from cyclic direct tension tests and Accelerated Loading Facility performance tests. The results demonstrate good agreement between the asphalt binder and mixture test results and pavement performance, indicating that the developed model framework is able to capture the asphalt binder’s contribution to mixture fatigue and pavement fatigue cracking performance.     

The use of natural rubber latex as a renewable and sustainable modifier of asphalt binder

Natural rubber (NR) powder as a bio-modifier of asphalt binder has been shown to have some beneficial effects. However, there is limited research into the use of the liquid form of NR, i.e. concentrated NR latex, as an asphalt binder modifier. Compared to NR powder, NR latex is cheaper and more accessible in some countries, and potentially creates viscosity-reducing foams in the modified binder during mixture production. In this research, asphalt binders modified with different amount of NR latex were systematically studied, including the rotational viscosities, rutting resistance, fatigue resistance, low-temperature behaviour and temperature sensitivity. The dispersion of the NR latex in the modified binders was examined using fluorescence microscope and atomic force microscope. Test results indicate that the addition of NR latex increases the viscosity and elastic recovery of the modified binders and potentially enhances asphalt pavements’ resistance to rutting, thermal cracking and fatigue damage. The NR latex also reduces the temperature sensitivity of the modified binders. The optimum NR latex content was found to be 7% of the total mass of the modified binder. A network of extensive microstructures mixed with bubbles was identified in the modified binders under heat. As a renewable and sustainable material, NR latex has the potential to be used as an effective asphalt modifier.     

Effect of warm mix additives on the interfacial bonding characteristics of asphalt binders

The quality of the interfacial bonding between asphalt binder and aggregates plays a significant role in determining the durability of asphalt mixtures. Warm mix asphalt (WMA) modifiers have been used extensively in the last decade primarily to reduce production and compaction temperatures as well as to improve workability of asphalt mixtures. This study aimed to provide better understanding of the effects of these WMA modifiers on the interfacial bonding between asphalt binders and aggregates. The evaluation focused on measuring surface energy of binders in unaged and aged states and aggregates and then calculating energy parameters that describe the potential of a given asphalt-aggregate combination to resist fatigue cracking and moisture damage. Results show that the combination of asphalt-WMA additive, as well as the content applied of WMA additive has a significant impact on the fatigue cracking and moisture damage resistance. The results suggest that it is poor practice to use a given type and percentage of WMA modifier without regard for binder type. Instead, test methods are recommended to evaluate the compatibility of asphalt binder, WMA additive type/content, and aggregates for improved performance at different conditions.     

Development of crumb rubber reinforced bituminous binder under laboratory conditions

Bituminous binders are widely used in the construction of flexible pavements. However, in some applications, the performance of conventional binders is not considered to be satisfactory. Reinforcing these binders with selected polymers prevents premature failure of a pavement by improving the properties of the binder. Another source of reinforcement comes from crumb (ground) rubber produced from waste tyres. After they have been worn-out during their limited service life, millions of used tyres are discarded every year and are hauled to a dump. The fatigue resistance at temperatures below normal service temperatures (25°C), one of the key engineering properties of crumb rubber reinforced binders, has been found to be lower than that of neat binders. This paper is concerned with the development of a rubber reinforced binder. It was shown that the binder has the potential to be used as an all-weather wearing course in flexible roads, whilst at the same time recycling a considerable amount of waste rubber.     

Study on viscosity of conventional and polymer modified asphalt binders in steady and dynamic shear domain

This study focuses on evaluating the flow behavior of conventional and polymer modified asphalt binders in steady- and dynamic-shear domain, for a temperature range of 20–70 °C, using a Dynamic Shear Rheometer (DSR). Steady-shear viscosity and frequency sweep tests were carried out on two conventional (VG 10 and VG 30) and two polymer (SBS and EVA) modified asphalt binders. Applicability of the Cox–Merz principle was evaluated and complex viscosity master curves were analyzed at five different reference temperatures. Cross model was used to simulate the complex viscosity master curves at different temperatures.It was found that asphalt binders exhibited shear-thinning behavior at all the test temperatures. The critical shear rate increased with increase in temperature and was found to be lowest for plastomeric modified asphalt binder. The Cox–Merz principle was found to be valid in the zero-shear viscosity (ZSV) domain and deviated at higher frequency/shear rate for all the binders. Results from the study indicated that the ratio of ZSV can be successfully used as shift factors for construction of master curves at different reference temperatures. Cross model was found to be suitable in simulating the complex viscosity master curves at all the test temperatures. Analysis of model parameters indicated that a strong relationship exists between ZSV and the critical shear rate. ZSV and critical shear rate varied exponentially with temperature. This relationship was used to propose a simple equation for assessing the shift factors for construction of master curves.     

Influence of commercial waxes and polyphosphoric acid on bitumen and asphalt concrete performance at low and medium temperatures

The influence of adding four types of commercial wax and one polyphosphoric acid to a non-waxy bitumen was investigated with regard to binder and asphalt concrete mixture performance. Binder properties were determined using dynamic shear rheometer (DSR), bending beam rheometer, force ductilometer and various conventional test methods. Asphalt concrete performance was investigated using tensile stress restrained specimen test (TSRST), creep test at −25,^˚C, dynamic creep test at 40,^˚C and complex modulus test at 0, 10 and 20,^˚C. Totally eleven binders and eight asphalt mixtures were investigated. TSRST fracture temperatures of the asphalt mixtures were marginally influenced by the addition of any of the additives, and significant physical hardening of the binders, observed by BBR testing, could not be established using TSRST. Also in creep testing of asphalt mixtures at −25,^˚C, recorded effects were less pronounced compared to binder testing. In dynamic creep testing, the smallest permanent strains were recorded for the asphalt mixtures containing FT-paraffin or montan wax, indicating better resistance to rutting. Adding polyethylene wax or polyphosphoric acid to the non-waxy bitumen used, showed considerable positive stiffening effects on the binder at medium and higher temperatures. However, this increase in stiffness could not be shown in dynamic creep testing (at 40,^˚C) of asphalt concrete mixtures containing these additives.     

Effect of warm mix asphalt chemical additives on the mechanical performance of asphalt binders

Warm mix asphalt (WMA) has become very popular in asphalt pavement construction because it allows reducing both energy consumptions and carbon emissions. WMA can be obtained by using different types of additives and can be produced, applied, and compacted at temperatures 20–40 °C lower than hot mix asphalt. WMA additives allow reducing the working temperatures without compromising the final performance of the asphalt concrete. Many WMA additives are available on the worldwide market and some of them reduce the viscosity of asphalts binder (organic additives or foam) whereas others do not act on this sense (chemical additives). This study focuses on the effect of chemical additives on the performance of asphalt binders for WMA production. To this purpose, a neat bitumen, a polymer modified bitumen (PMB) and two different chemical additives were selected. All the binders were characterized through conventional tests, DSR, MSCR, FTIR and microscopic analysis. The result clearly showed that the influence of the chemical additives on the neat bitumen is negligible or non-existent. On the contrary, significant changes were observed in the modified bitumen properties. Specifically, chemical additives reduce the viscosity temperature susceptibility of PMBs in the temperature range between 80 and 140 °C, increase the rutting resistance potential and the elastic response of PMBs at high temperatures. Moreover, a morphological inspection supported the modifications observed in the rheological properties of PMBs.     

Fatigue life and endurance limit prediction of asphalt mixtures using energy-based failure criterion

Fatigue cracking is one of the major types of distress in asphalt mixtures and is caused by the accumulation of damage in pavement sections under repeated load applications. The fatigue endurance limit (EL) concept assumes a specific strain level, below which the damage in hot mix asphalt (HMA) is not cumulative. In other words, if the asphalt layer depth is controlled in a way that keeps the critical HMA flexural strain level below the EL, the fatigue life of the mixture can be extended significantly. This paper uses two common failure criteria, the traditional beam fatigue criterion and the simplified viscoelastic continuum damage model energy-based failure criterion (the so-called G^R method), to evaluate the effect of different parameters, such as reclaimed asphalt pavement (RAP) content, binder content, binder modification and warm mix asphalt (WMA) additives, on the EL value. In addition, both failure criteria are employed to investigate the impacts of these parameters in terms of the fatigue life of the study mixtures. According to the findings, unlike an increase in RAP content, which has a negative effect on the mixtures’ fatigue resistance, a higher binder content and/or binder modification can significantly increase the EL value and extend the fatigue life as was proved before by other researchers, whereas WMA additives do not significantly affect the mixtures’ fatigue behaviour. A comparison of the model simulation results with the field observations indicates that the G^R method predicts the field performance more accurately than the traditional method.     

A rheological study on aged binder rejuvenated with Pongamia oil and Composite castor oil

Recycling of highway materials is an effort to preserve the natural environment, reduce waste and provide a cost-effective way for construction of highways. The reclaimed asphalt pavement (RAP) contains stiffened binder caused by loss of volatile materials and oxidation. Hence, the addition of high amount of the RAP to asphalt mix may make it prone to fatigue failure. Due to this reason, addition of RAP to asphalt mixture in substantial amount has been a challenge so far. Therefore, ‘rejuvenators’ which are supposed to restore chemical and physical properties of the aged asphalts are used effectively in asphalt mixture. In this study, two locally available oils, i.e. pongamia oil (locally known as Karanja oil) derived from the seeds of Pongamia pinnata and a composite rejuvenator made of castor oil and coke oven gas condensate have been explored for rejuvenating the aged binder. The rheological properties of aged binder and rejuvenated binders were studied using a dynamic shear rheometer. From the various rheological tests conducted, it was found that certain proportion of pongamia oil as well as composite castor oil was able to impart desirable rutting as well as fatigue performance for the rejuvenated binder samples. The thermal analysis carried out using thermogravimetric analysis ensured adequate thermal stability for the binder specimens treated with these oils. In terms of binder performances, it was found that these oils could be considered as suitable rejuvenators for effectively restoring properties of the aged binder. Performance studies on RAP mixes may be extended for recommending these two oils as rejuvenators for hot mix pavement recycling.     

Introducing a new specimen shape to assess the fatigue performance of asphalt mastic by dynamic shear rheometer testing

Early failure of asphalt pavements is a common issue all around the world. Damages are caused by various reasons like insufficient binder or aggregate quality, an inadequate mix design or improper handling in the production/construction process. The effects of binder, aggregates and mix design have been widely studied and state-of-the-art testing methods are available for both, hot-mix asphalt (HMA) and for each component. An important part in HMA belongs to the asphalt mastic, where no standardized method is available to allow a quality control. Asphalt mastic is the mix of bitumen with aggregates smaller than 63 (125) µm and covers the coarse aggregates as the actual binding component in the mix. This research aims at developing a testing method for asphalt mastic based on fatigue tests. The dynamic shear rheometer (DSR) was found as a suitable device for this purpose. The DSR fatigue test consists of the 8 mm parallel-plate geometry widely used for binder performance grading with a sample height of 3 mm. Instead of a cylindrical specimen shape, a hyperboloid of one sheet is applied. This shape predetermines the point of failure and prevents adhesion/interface failures between the mastic specimen and the upper or lower DSR stainless steel plate. The specimens are prepared directly in the DSR employing a silicone mould to ensure an exact specimen shape. This test can be applied to all DSR devices without costly changes or additional equipment as long as sufficient cooling capacity and torque can be provided from the DSR. This fatigue test makes it possible to assess the fatigue performance of binders and mastic samples.