Epoxy asphalt attracted the attention of road authorities in many countries as a solution for du-rable open-graded porous asphalt (OGPA) surface layers with enhanced longevity. Nevertheless, the recycla-bility of aged epoxy asphalt materials has not been thoroughly studied yet. This research presents an experi-mental program conducted in the laboratory to assess the potential recyclability of epoxy-modified open-graded porous asphalt (EMOGPA) mixes. Results indicate that the aging increased the tensile strength of studied mixes, with the strength and strength development rate of aging EMOGPA mixes to be almost identi-cal to standard OGPA mixes. The EMOGPA mixes have shown higher resistance against water damage than the OGPA mixes supporting the claim that the stone-mastic adhesion is improved with the use of epoxy bind-er. It was also proven that the aged material containing the epoxy binder could be re-melted to produce new pavement materials. The new EMOGPA mixes with the recycled epoxy material exhibited similar durability characteristics with the recycled standard OGPA mixes.@en

This research aims to evaluate the potential environmental impact of epoxy-modified asphalt used as a pavement material for roadways in the Netherlands and identify what determines the environmental performance of the epoxy asphalt technology through life cycle assessment. Results indicated that the incor-poration of epoxy binder in asphalt could lead to significantly lower environmental impact than the unmodi-fied asphalt. Such benefits are attributed by the minimal maintenance interventions of a pavement with epoxy and their remarkably higher service life over the analysis period. Finally, although the initial price of epoxy-modified asphalt production and construction was substantially higher than of standard asphalt mixtures, the overall score of epoxy-modified asphalt pavement in all weight scenarios was lower than that of the reference structures reflecting the sustainability benefits of using this technology for roadway pavements.@en

Epoxy-asphalt (EA) attracted the attention of road authorities in many countries as a solution for open-graded porous surface layers with enhanced durability and longevity. This research presents an experimental programme to assess the durability of epoxy-modified open-graded porous asphalt (EMOGPA) mixes, emphasising the effects of the reactivity of two mineral fillers on mixes containing various EA proportions. Results indicate that the EMOGPA mixes have shown a high sensitivity to the conditioning time before compaction (aka. preconditioning). The materials produced exclusively by EA are the most sensitive to preconditioning, reducing their water and ravelling resistance with increased preconditioning time lengths. The number of gyrations has also been proven as an efficient quantity of the compaction effort required to reach the target mix properties. Moreover, the proportional increase of EA in mixes led to substantially improved durability. Hydrated lime in epoxy-modified asphalt mixes also affected their mechanical response. The indirect tensile strength and toughness of EA mixes were higher than other mixes, while mixes with limestones were stronger and tougher than those with hydrated lime. This attribute reflects the positive contribution of apolar fillers to strengthen and toughen the EA mixes.@en

Bituminous binders are foreseen as colloidal dispersed systems characterised by high chemical complexity containing a plethora of molecules classified into maltenes and asphaltenes. The effect of these fractions on the overall response of bituminous binders remains elusive. This research selected two binders from the same refinery but with different paving grades. First, Dynamic Shear and Bending Beam Rheometers were employed to assess their rheological properties, and results were consistent with the physical measurements conducted on binders to address low to high temperature rheological response. Then, the binders and their fractions were individually analysed in a Fourier transform infrared spectroscopy and differential scanning calorimetry to elucidate their chemistry associated with the structural changes. No significant difference could be noticed in the infrared spectra of binders, even if they displayed diverse physical properties. Differences may be identified in asphaltenes, an observation which is also supported by calorimetric measurements where steric hindrance occurred upon heating. Maltenes contributed significantly to the glass transition of both binders, while the impact of asphaltenes on the heat capacity changes in glass transition was limited. The findings from this research could be used to establish a new analytical approach for bituminous binders to understand the differences in the physical properties of binders based on their chemistry.@en

Glass transition parameters can be used to study the miscibility, or lack of it, in polymer-modified asphalt binders. In this study, the contribution of thermodynamics of mixing to glass transition was quantitatively assessed in a differential scanning calorimeter for four asphalt binders partially and fully replaced by an epoxy system. The values of heat capacity (C_p) and, subsequently the glass transition temperature (T_g) of all binders were determined to quantify the miscibility based on the entropic changes. Emphasis was also given to examining the enthalpy of mixing as a function of epoxy system composition during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations of the measured T_g of epoxy-modified asphalt binders (T_g,mix) obtained from the ideal mixing rule led to negative values of the entropy of mixing (ΔS_mix^c), dictating the presence of internal repulsive forces between the asphalt and epoxy components. Softer binders were associated with binders of low deviations of T_g,mix values from the ideal mixing rule. Lastly, the partial replacement of asphalt binders by the epoxy system increased the T_g and decreased the amount of ΔS_mix^c, and such performance imposes the formation of immiscible products.

@en

Pavements of enhanced longevity would be expected to withstand long-term traffic as well as varying environmental conditions reducing in this way the major maintenance needs. Considering also the adoption of long-term contracts by road authorities, long-life pavements have started to attract the interest of road contractors worldwide. New and relatively new binders specially designed to produce long-life pavements have been proposed to minimize the regular maintenance and reconstruction operations. Among others, one promising technology to reach this goal is the epoxy modified asphalt binder, or epoxy-asphalt. Nevertheless, the addition of epoxy resins to asphalt binders may result in materials of inferior properties. Thermosetting epoxy resins may not mix homogeneously in asphalt binders leading to immiscible or partially miscible binders, which are mostly phase-separated materials. The phase-separated epoxy-asphalt binders can become brittle and thus more prone to cracking, leading the pavements to fail. Only a few epoxy products are applicable in asphalt binders, and the knowledge of incorporating chemistry to develop miscible epoxy binders remains unknown. For this to be the case, this thesis aims to provide a fundamental approach to elucidate the chemical and physical processes that determine the phase behavior of these binders. A vital role in implementing the thermosetting epoxy-asphalt binders also plays the curing. To obtain fundamental insights into the material curing, multi-physics models and experimental methods are considered in this research to identify and assess the curing-induced changes of epoxy-asphalt. The development of rheological properties that reflect the material workability is determined by laboratory experiments and used as input to multi-physics simulations. As the ultimate scope of implementing the epoxy-asphalt is to increase the longevity of pavements, the oxidation-induced changes of epoxy-asphalt materials as a function of time are evaluated as well in this research to prove their high aging resistance for wearing courses. Within the same framework, emphasis is also given to the effect of epoxy-asphalt on the durability and mechanical performance characteristics of an asphalt concrete mix. In conclusion, this thesis contributes to elucidating the factors that determine the curing- and oxidation-induced changes of epoxy-asphalt and understanding what bears miscible binders. The modeling and experimental programs discussed throughout the thesis can help to provide the fundamental knowledge to design and develop new binders and binding systems of the desired properties and characteristics.@en

In this study, a series of viscosity tests were performed to investigate various conditions, i.e. temperature, shear rate and dilution level, on the curing behavior of epoxy bitumen. The results show that curing rate of epoxy bitumen increased with temperature; high shear rate would interfere the formation of crosslinks in epoxy bitumen, resulting in a negative effect on curing rate; diluting epoxy bitumen by a base bitumen was an effective way to control the curing rate and reduce the material cost. Considering the workability and durability of paving materials, it is recommended that dilution level of epoxy bitumen is 25%, mixing rate is 20 r/min, curing temperature is 130 ℃, and the pavement construction should be finished within 5 hours.

@en

Pavement materials containing epoxy-asphalt are mainly used to enhance the fatigue cracking resistance of surfacing layers on bridges. These materials have also been proposed for roadways, but limited field data are available. In this research, a fully instrumented epoxy-modified asphalt surfacing layer was applied to measure strain responses in service conditions. Results over the first-year monitoring period indicated that the epoxy-modified asphalt behaves fundamentally similarly to a reference one with an asphalt mix of the same aggregate gradation. The epoxy-modified asphalt demonstrated the lowest transverse compressive strains at decreased temperatures, reflecting the potentially high material resistance against thermal cracking. After the summer period, the modified material showed lower tensile strains than the reference mix compared with the previous time period. Such an attribute could indicate the ongoing curing-induced stiffening of epoxy-modified asphalt at high temperatures during summer. The longitudinal and transverse strain measurements had inverse tendencies at all temperatures. Finally, the mechanical response of the studied materials after the summer has been examined using a classical fatigue cracking model and following a life cycle assessment methodology, and preliminary findings support the use of epoxy-asphalt for sustainable pavements.@en

In the past years, the use of liquid additives as bitumen modifiers has increased to enhance or adjust the properties of bitumen for wide range of applications. Their molecular composition and mutual interaction result in a specific phase morphology in the binders. Hence, there is a need to evaluate the phase and interphase framework and physical properties of complex binders. The RILEM Technical Committee 272-PIM ‘Phase and Interphase behaviour of innovative bituminous Materials’, Task Group TG1 investigates the characterization of assessing phase interphase properties of complex bituminous binders. In this framework, three liquid additives have been selected with different viscosity, nature and use. They were blended with base bitumen to achieve similar consistency and the blends were further aged. Physical properties were evaluated through rheology using dynamic shear rheometer (DSR) in a wide range of conditions. The phase morphology was addressed by atomic force microscopy (AFM), differential scanning calorimetry (DSC) techniques. AFM and DSC results, from fresh and aged binders, reveal that each binder display specific phase morphology and glass transition characteristics, manifesting mutual compatibility of the individual binder components. This approach of binder assessment: combining phase characteristics and rheological response can assist material selection to specific applications.@en

Lignin, one of the most abundant natural polymers, has been extensively studied as an additive in bituminous binders. Even though the lignin improves the overall resistance against oxidative aging of bitumen, it could lead to high thermal cracking sensitivity. In this study, a bio-oil (i.e., rapeseed oil) is implemented in lignin-modified bitumen to ameliorate characteristics, such as the resistance to fatigue and cracking. The long-term aging of bitumens formulated by different proportions of bio-oil was simulated by the pressure aging vessel (PAV) method. Fourier Transform Infrared Spectroscopic (FTIR) results demonstrated lignin has a remarkable antiaging effect, but adding bio-oil will slightly deteriorate the antiaging effect. The Brookfield rotational viscometer showed that the addition of bio-oil was able to reduce the binder’s viscosity observably, thereby improving the workability of bitumen. The frequency sweep tests revealed that lignin increased the stiffness and improved the thermal stability. Also, the multiple stress creep recovery tests corroborated that lignin significantly enhanced the rutting resistance of binders. The fatigue and thermal cracking properties of lignin-modified binder could be strengthened by increasing bio-oil content which is confirmed from both linear amplitude sweep, Glover-Rowe parameter, and Bending Beam Rheometer (BBR) tests. Moreover, the relaxation test results demonstrated that bio-oil decreased the residual stress ratio and relaxation time dramatically. Overall, this study has shown preliminary conclusions on the incorporating of bio-oil to enhance the medium-low temperature properties of lignin-modified binders. In the meantime, bio-oil did not interfere with the improvement influence of lignin on the neat bitumen regarding high-temperature performance.@en

In de wegenbouw is duurzaamheid een belangrijk speerpunt. Daarom wordt er gezocht naar nieuwe bindmiddelen en modificaties om duurzame oplossingen te vinden voor de alsmaar groeiende verkeersstromen. Met de introductie van asfalt met epoxygemodificeerde bitumen wordt een grote stap gezet in het realiseren van robuuste wegen met een langere levensduur. Door de jaren heen is asfalt met epoxybitumen wereldwijd toegepast als een hoogwaardig verhardingsmateriaal met een lange levensduur, vooral als wegdek op stalen brugdekken. In Nieuw-Zeeland wordt sinds 2007 asfalt met epoxybitumen als deklaag gebruikt. Om tot een balans te komen tussen kosten en prestaties wordt daar sinds 2012 gekozen voor een mengvorm van epoxybitumen met gewone bitumen. Inmiddels ligt er al een miljoen vierkante meter ZOAB met epoxygemodificeerde bitumen. In 2017 is door de TU Delft, provincie Noord-Holland en Dura Vermeer het initiatief genomen om epoxygemodificeerde bitumen in Nederland te introduceren. Aan de TU Delft zijn vanaf 2018 twee PhD’s gestart om epoxygemodificeerde bitumen voor de Nederlandse situatie te onderzoeken. De laboratoriumonderzoeken bij de TU Delft en Dura Vermeer wijzen uit dat de epoxygemodificeerde mengsels in het algemeen betere eigenschappen hebben dan mengsels met standaard bitumen. Asfalt met epoxygemodificeerde bitumen gaat naar verwachting veel langer mee dan de huidige asfaltmengsels. De langere levensduur leidt tot een lagere milieubelasting. De meerkosten ervan zijn aanzienlijk maar vanwege de langere levensduur zijn de life cycle costs lager. Er is minder hinder voor het verkeer omdat de weg minder vaak hoeft te worden voorzien van een nieuwe asfaltlaag. En tenslotte, als het dan uiteindelijk toch versleten is, kan het goed worden hergebruikt. Het is echter moeilijk om de langere levensduur te kwantificeren, hier is geen algemeen geaccepteerde meetmethode voor. Om de praktijkeigenschappen te monitoren, zijn direct al diverse proefvakken aangelegd. De betere hechting, de betere prestatie na veroudering (zoals vorst-dooi cycli) en de verbeterde weerstand tegen rafeling kunnen duiden op een langere levensduur. Tot nu toe presteren alle proefvakken naar verwachting. De paper beschrijft de proefvakken en enkele proefresultaten.@en

The glass transition parameters are used to study the miscibility, or lack of it, in polymer modified asphalt binders. In this study, a quantitative assessment of the contribution of thermodynamics of mixing to glass transition was conducted in a differential scanning calorimetry for four asphalt binders modified with an elastomeric epoxy system. Especially, the values of heat capacity (Cp) and subsequently the glass transition temperature (Tg) of all binders were determined to quantify the miscibility based on the entropic changes. Emphasis was also given on examining the enthalpy of mixing as a function of the composition of epoxy asphalt binders during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations of Tg,mix obtained from the ideal mixing rule, or 𝛥𝑇𝑔,𝑚𝑖𝑥, led to negative values of the entropy of mixing (𝛥𝑆𝑚𝑖𝑥𝑐), dictating the presence of internal repulsive forces between the asphalt and epoxy components. The soft in properties and sol type base binders are also associated with epoxy asphalt binders of low 𝛥𝑇𝑔,𝑚𝑖𝑥 values. Overall, the incorporation of the epoxy system in asphalt binders increases the Tg and decreases the amount of 𝛥𝑆𝑚𝑖𝑥𝑐, and such performance imposes the formation of phase-separated binders.@en

Crumb rubber modified bitumen (CRMB) can be regarded as a binary composite system in which swollen rubber particles are embedded in the bitumen matrix. Previous study has successfully implemented the micromechanics models in predicting the complex moduli of CRMB binders using more representative constituent parameters. In the regime of master curves, while the micromechanics models used predicted well in the high-frequency range, they underestimated the complex modulus in the low-frequency range. The current study aims to further improve the prediction accuracy of micromechanics models for CRMB by considering the interparticle interactions. To accomplish this goal, a new reinforcement mechanism called chain entanglement effect was introduced to account for the interparticle interaction effect. Results show that the polymer chain entanglement effect accounts for the underestimation of complex modulus and lack of elasticity (overestimation of phase angle) for CRMB at high temperatures/low frequencies. The mechanical properties of bitumen matrix and entangled polymer network can be determined based on the rubber content. The introduction of the entangled polymer network to the generalized self-consistent model significantly improved the prediction accuracy for both complex modulus and phase angle in the whole frequency range. In summary, by incorporating the physio-chemical interaction mechanism into the currently available models, a new dedicated micromechanics model for predicting the mechanical properties of CRMB has been developed. The predicted viscoelastic behaviors can thereafter be used as inputs for an improved mix design.@en

Membranes of sufficient bonding characteristics could improve the integrity of the multi-layer structures on orthotropic steel deck bridges (OSBDs), enhancing thus the structural response of these systems and, ultimately, their service life. In this research, full-scale experiments were performed at the LINTRACK accelerated pavement testing facility of the Delft University of Technology to evaluate the performance of two surfacing systems commonly used in the Netherlands, giving emphasis on assessing the interface response of membranes with the surrounding materials. Results indicated that the tensile strains remain almost uniform at the top of porous asphalt, in both transverse and longitudinal directions, as no appreciable loss in stress-carrying capabilities was seen even at the end of the testing program. The sections exhibited similar behaviour in terms of strains, with some differences in strains indicating the impacts of membranes at interfaces. The importance of membranes of the desired bonding characteristics was also reflected by the relative displacement measurements. The relative interlayer slip had been higher in the transverse direction than the longitudinal one, with slightly higher displacements in one of the test sections. Overall, no cracking was observed on either section, and the current findings support the use of membranes between surfacing layers on OSBDs.

@en

The RILEM TC 272 PIM (Phase and Interphase behaviour of innovative bituminous Materials) – TG1 Binder has initiated an inter-laboratory program investigating the phase and interphase behaviour of bituminous binders. Five laboratories evaluated the low temperature properties of seven standard and complex binders with differential scanning calorimetry (DSC). DSC has been accepted as a powerful tool to evaluate, among others, the glass transitions, Tg, monitoring the endothermic or exothermic heat flow of a material under controlled temperature conditions. There are different ways to run the test, conventional temperature linear-DSC (TL-DSC), and temperature modulation-DSC (TM-DSC). The latter has been proven as an efficient method differentiating the structural relaxation phenomena from the heat capacity. In this study, emphasis was laid on comparing the Tg measured by TL- and TM-DSC improving the interpretation of binder glass transitions. To restrain the scope of this study, two SBS polymer modified binders (PmBs), a commercially available PmB and an highly modified PmB (7.5 % SBS) , were evaluated and compared with two neat bituminous binders. It was observed that the modification by 7.5% SBS resulted in a decrease of the Tg. This reduction of Tg reflects the positive influence of SBS at low temperatures. @en

The glass transition parameters are used to study the miscibility, or lack of it, in polymer modified asphalt binders. In this study, a quantitative assessment of the contribution of thermodynamics of mixing to glass transition was conducted in a differential scanning calorimetry for four asphalt binders modified with an elastomeric epoxy system. Especially, the values of heat capacity (Cp) and subsequently the glass transition temperature (Tg) of all binders were determined to quantify the miscibility based on the entropic changes. Emphasis was also given on examining the enthalpy of mixing as a function of the composition of epoxy asphalt binders during curing to ensure that these binders were completely crosslinked for further analyses. In all cases, the positive deviations of Tg,mix obtained from the ideal mixing rule, or ΔT_(g,mix), led to negative values of the entropy of mixing (ΔS_mix^c), dictating the presence of internal repulsive forces between the asphalt and epoxy components. The soft in properties and sol type base binders are also associated with epoxy asphalt binders of low ΔT_(g,mix) values. Overall, the incorporation of the epoxy system in asphalt binders increases the Tg and decreases the amount of ΔS_mix^c, and such performance imposes the formation of phase‐separated binders.@en

In the past years, the use of liquid additives as bitumen modifiers has increased to tailor the rheology of bitumen for a wide range of applications. Their chemical composition and mutual interaction result in specific phase morphologies in the binders. Hence, there is a need to evaluate the phase morphology of complex binders and the impact of additives on their physical properties. The RILEM Technical Committee 272-PIM ‘Phase and Interphase behaviour of innovative bituminous Materials’, Task Group TG1 assessed the phase and interphase properties of bituminous binders. Some preliminary results are presented on blends using three liquid additives and a neat 35/50 bitumen. The goal of formulating the blends was to achieve similar consistency of a pen grade 70/100 bitumen at the original state and to evaluate the binders at both original and after aging. Physical properties were evaluated through rheological characterisation using a dynamic shear rheometer (DSR) in a wide range of conditions. The phase morphology was assessed using atomic force microscopy (AFM). Differential scanning calorimetry (DSC) was also used for the characterisation of the thermal behaviour of the binders. While conventional properties, as obtained from the routine binder testing methods, hardly distinguish between blends, the cross-over temperature, derived from DSR measurements, enabled to dictate the impact of liquid additives on the physical properties of bituminous binders at intermediate temperature. AFM confirmed a difference in phase morphology between the blends, whereas some binders displayed new phases at original and aged conditions. Glass transition, as determined by DSC, also showed a difference in the low-temperature domain that may be explained with the difference in phase morphology. Overall, an in-depth understanding of microstructure morphology and glass transition behaviour of complex binders can assist in designing future specifications to distinguish durable bituminous materials better.@en

InfraRed spectrometry is a powerful technique to characterise bituminous binders. The methodology is not fully harmonised and may lead to vari-ability. The RILEM-272-PIM-TG1, evaluated seven complex bituminous, for which eleven laboratories performed FTIR. While, the spectra showed sim-ilar trends, further analysis was needed to improve comparison. A specific approach was applied on two binders, unmodified and polymer modified bitumen, and two ageing conditioning. Combining a Gaussian distribution
and derivative analysis confirmed a good alignments of laboratory results. A two-step model was developed improving further interpretation. It con-sists of a baseline adjustment with eight points and normalisation over the maximum aliphatic peak. Furthermore, a specific fingerprint model was determined with the main absorption peaks defined by their location and shape. Only the intensity varies from laboratory to laboratory and binders. This general approach can be used as a platform to characterise aging or binder complexity@en

This research involving two binders, a neat 70/100 paving grade bitumen and an epoxy-diluted bitumen, evaluated the effect of hydrated lime and limestone filler on the oxidative age hardening of binders. A pressure aging vessel (PAV) unit was used to mimic long-term oxidative aging, and the rheological properties of binders containing fillers were measured using a dynamic shear rheometer. The active nature of hydrated lime with binders was further verified by conducting elongation-to-fracture tensile tests. Results indicate that the effect of the filler reactivity is much more pronounced in epoxy bitumen than in neat bitumen, with the pure limestone filler showing the highest stiffening effect. The epoxy bitumen containing limestone filler was also tougher, showing higher elongation-to-break than the mastics generated with hydrated lime. Even though the epoxy bitumen containing limestone was the strongest and toughest material, it exhibited higher susceptibility to fracture after 80 h in PAV than of the same binder with hydrated lime. This research verifies earlier studies that hydrated lime could improve the low-temperature properties, resulting in the reduction of the deleterious effects of oxidative age hardening in bituminous binders.@en

Lignin, one of the most abundant natural polymers, has been extensively studied as liquid or solid additive in bituminous binders. Despite the fact the organosolv lignin in bitumen improves the overall resistance against oxidative aging, lignin could lead to binders of high thermal cracking sensitivity. In this study, a bio-based oil is implemented in a lignin modified bitumen to ameliorate characteristics, such as fatigue and thermal cracking resistance. Pressure aging vessel conditioning was applied to new binders formulated by different proportions of bio-oil to simulate the long-term aging. A series of rheological tests were performed. Based on the linear amplitude sweep test results, fatigue damage of lignin-bitumen could be reduced by increasing the oil content. According to relaxation test results, the addition of oil significantly decreased the ratio of residual stress and relaxation time. This study has shown preliminary conclusions on the use of bio-oil to improve the low-intermediate temperature performance of lignin-bitumen binders.

@en