Aged Binder Research Articles

Effects of crystalline wax and asphaltene on thermoreversible aging of asphalt binder

ABSTRACT Thermoreversible aging is an important factor that affects the durability of asphalt pavement in cold and high altitude areas. Although there has been increasing attention to the significance of thermoreversible aging in recent years, the contribution of asphalt components to thermoreversible aging remains unclear in the existing literature. To this end, potential components that may affect the thermoreversible aging of asphalt binders were regarded as additives in this study. The extended bending beam rheological test (ExBBR), thermal stress calculation, and modulated differential scanning calorimetry (MDSC) analysis were employed to study the effects of two kinds of crystalline waxes with different carbon atoms and one asphaltene type as additives on the thermoreversible aging properties of asphalt binder. The findings showed that under conventional 1-hr conditioning cold storage, adding 1% or 3% C20H42 significantly improved the low-temperature rheological properties and reduced base asphalt's thermal stresses. However, no significant effect of the C20H42 additive on thermal stress reduction was observed when considering the asphalt binder's thermoreversible aging. Both low-temperature rheological tests and thermal analysis confirmed that C20H42 significantly increased thermoreversible aging in the base binder; however, C32H66 and asphaltene additives did not produce a similar effect.

Measurement of particle agglomeration and aggregate breakdown of reclaimed asphalt pavement

Cold milling of old asphalt pavement is widespread in pavement resurfacing. It produces reclaimed asphalt pavement (RAP) and changes the state of the old asphalt pavement; the pavement is cut into particles, known as RAP particles. RAP particles are composed of many smaller aggregates bonded by the aged binder (particle agglomeration). The aggregates contained in the old pavement can be crushed into smaller pieces in the milling operation (aggregate breakdown). Particle agglomeration increases the risk of insufficient moisture stability and fatigue resistance of the recycled asphalt mixture; aggregate breakdown often prevents the use of a higher RAP content in the new mixture. In this study, the effect of these two problems is studied through a pavement maintenance project. The effect of milling speed on the RAP particle agglomeration rate is evaluated. The size-susceptibility of the agglomerate d particles, gradation deviation of the recycled mixture, and morphology classification of RAP particles are discussed. The effect of milling speed on aggregate breakdown is also investigated. The results show that approximately 30%–50% of RAP particles are made of aggregates smaller than the corresponding particle size. The agglomeration rate increases with an increase in milling speed and RAP particle size. High milling speed produces a lower rate of aggregate breakdown, resulting in a higher coarse aggregate content and a lower filler and fine aggregate content than a low milling speed.

Increasing pavement bitumen adhesion with DAD adhesion additives

An important factor that largely determines the water resistance and durability of asphalt pavements is the adhesion of bituminous binders to the surface of stone materials. The most common method of increasing the adhesion of binders is the use of adhesive additives. Given that the range of adhesives used in the road industry is con-stantly updated, and their effectiveness is determined by the characteristics of binders and stone materials, issues related to the assessment of the impact of additives on the properties and, in particular, the adhesion of bituminous binders, are relevant. Goal. The aim of the study was to evaluate the effects of adhesive additives of the DAD series on the proper-ties of bitumen used in the road industry of Ukraine. Methodology. For bitumen modified with DAD-1, DAD-K and DAD-KT 2 additives, standard quality indicators have been determined in accordance with the norms of national standards DSTU 4044 and SOU 45.2-00018112-067. Particular attention was paid to determining the adhesive properties of binders, which were evaluated by the method of adhesion to the glass surface and the method of rotation of the bottle, and the thermal stability of additives is evaluated by changes in adhesion after aging of binders by TFOT and RTFOT. Based on the obtained experimental data, it was found that the adhesion additives of DAD have practically no effect on the basic standard quality indicators of road viscous bitumen. When modifying bitumen with the maximum concentrations recommended by the manufacturer, the additives significantly increase the adhesion of bitumen to the glass surface. The surface of the grains of the ac-cepted stone materials treated with bitumen modified with the additive DAD-KT 2, after the test by the method of rotation of the bottle for 6 hours showed 40% of them remain covered with binder. Novelty. The thermal stability of DAD adhesive additives significantly depends on the accepted method of aging. The main factor that reduces the adhesive properties of the DAD-1 additive is the intense interaction with air. The adhesion properties of bitumen modified with the addition of DAD-CT 2 is significantly increased after aging. Practical value. The expediency and efficiency of the use of additives of the DAD series in the production of asphalt concrete mixtures should be established based on the characteristics of the bitumen and stone materials used.

Development of a Matrix Analysis Methodology for Characterization of Short-Term Aging in Asphalt Binders Modified by Synthetic Wax

In this study, an innovative methodology is proposed to characterize the short-term aging of asphalt binders using the matrix analysis method. The rotational viscosity and complex shear modulus of asphalt binders were chosen as target rheological properties for the analysis of aging. A set of square matrices was developed based on test temperatures and the synthetic additive wax content. Transformational short-term aging matrices were obtained that characterize the trend of the aging process as a function of binder type, temperature sweep, and additive percentage. The results of the matrix analysis show that the trend of short-term aging depends on the binder performance grade and the rheological characteristic chosen for the analysis of aging. In addition, transformational aging matrices can provide detailed information about the range of the aging rate and the trend in aging for each binder type. Furthermore, the components of the transformational matrices clearly show the sensitivity of the binders to aging. In conclusion, the matrix analysis of aging can be used to compare the effects of short-term aging of different asphalt binders.

Study on the effects of reversible aging on the low temperature performance of asphalt binders

Reversible aging refers to a time-dependent stiffening of asphalt binder that results from the time-delayed increase in stiffness when the asphalt binder is stored at low temperatures. The increase in stiffness will distinctly affect the low temperature performance of the asphalt binder, but existing researches rarely consider this. This paper aims to investigate the effects of reversible aging on the low temperature performance of asphalt binders, and to reveal the underlying mechanism of reversible aging. To this end, four different types of asphalt binders were selected for the extended bending beam rheometer (EBBR) test at different conditioning times. The thermal stress was computed based on the rheological data obtained from the EBBR test to quantify the influence of low temperature reversible aging on the cracking resistance of the asphalt binders. The Avrami isothermal crystallization kinetics theory was used to analyse the reversible aging process of asphalt binders from the perspective of macro-crystal structure. Furthermore, the molecular dynamics was performed to simulate the reversible aging process of asphalt binders from a microscopic point of view. The results from this study show that the low temperature performance of asphalt binders continues to decline with the extension of the conditioning time, which is manifested by the increase in grade loss, thermal stress and critical cracking temperature. Reversible aging exhibits great impact on the low temperature performance of asphalt binders by lowering the low temperature grade of asphalt binders up to one grade. The Avrami isothermal crystallization kinetic theory can accurately characterize the reversible aging tendency of asphalt binders. The molecular dynamics simulation results show that the asphaltene component contributes the most to the reversible aging of asphalt binder.

Effects of Aging on the Physical and Rheological Properties of Trinidad Lake Asphalt Modified Bitumen.

The application of various modifiers has emerged in recent years to improve conventional petroleum-based bitumen properties. The natural asphalt called Trinidad Lake Asphalt (TLA) has been applied very often due to its consistent properties, high viscosity and density, and superior rheological properties, and effective blending with other bitumen. However, most studies on TLA-modified binders always focused on physical and rheological properties in the original (unaged) condition, but the details about aging properties are often neglected. This study aimed to investigate the effect of short-term aging on the physical and rheological characteristics of the 35/50 base bitumen modified by the addition of two different TLA contents. The conventional physical tests and dynamic shear rheological tests were undertaken before and after aging to measure the penetration and softening point, complex shear modulus, and phase angle of the modified binders, as well as to calculate the zero shear viscosity using the Cross model fitting procedure. Based on the results of the above-mentioned comprehensive testing, the effect of aging on TLA-modified binder properties was evaluated using aging indices, as well as a direct comparison of results. The tests revealed that the short-term aging of TLA-modified binders did not worsen or reduce the pavement resistance to permanent deformation or the load-bearing capacity of the asphalt mixture.

Properties of Bitumen Modified with Latex Under Short-Term Ageing

Short-term ageing is a common issue in bitumen mixing production, and it severely affects the physical, rheological and chemical properties of the bitumen. Polymer modified bitumen is regarded as a preferable paving material to improve the performance of asphalt pavement against binder ageing. One of the additive types used to innovate modified bitumen is natural rubber (latex). This study evaluated the physical properties of bitumen modified with latex under ageing condition. Different percentages of latex (i.e. 2.5%, 5.0%, 7.5% and 10.0%) were added to the control 60/70 penetration grade (PEN) bitumen, which was then tested for penetration, softening point, viscosity, loss on heating and storage stability. The bitumen samples were conditioned under short-term ageing (i.e. rolling thin-film oven) prior to performance tests. Results indicated that modifying bitumen with latex hardens the conventional bitumen 60/70 PEN and potentially improves the bitumen’s resistance against temperature susceptibility with a high value of softening point. The addition of latex up to 10% produces a homogenous blend even after short-term ageing condition.

Effect of rejuvenator type and dosage on rheological properties of short-term aged binders

Using reclaimed asphalt pavement (RAP) material in pavement construction is typically an environmentally friendly practice. However, the asphalt available in RAP is already oxidized and stiffened due to various environmental processes. To compensate these problems, rejuvenators can be mixed with aged binder with the aim of restoring its original properties. This study investigates the performance of aged binders blended with three different types of rejuvenators. Thin film oven test aged PG 58–28 binder was mixed with raw waste cooking oil (R1), modified waste cooking oil (R2), and Hydrolene H90T (R3) at the concentrations of 3%, 6% and 9% by the weight of the total binder. To enhance rutting resistance, styrene–butadiene–styrene was also blended with rejuvenated binders and tested. Frequency sweep testing at a wide range of temperatures and frequencies was conducted in the Dynamic Shear Rheometer, and time–temperature superposition was used to obtain parameters including Superpave, Glover-Rowe, Shenoy, Crossover frequency and Rheological index parameters. In addition, the Multi Stress Creep Recovery test was performed to gain an in-depth understanding of the rutting performance of the binders. Based on the comparative study of different rejuvenated binders, the binder rejuvenated using a chemically modified waste cooking oil seems to most be effective in improving the overall performance of the binder without compromising its rutting resistance. In addition, the relationship between different cracking parameters indicated that they are not all compatible with each other in terms of ranking binder performance. Finally, the MSCR parameter seems to more effectively capture the influence of rejuvenation and SBS addition to rejuvenated binders more than other parameters.

Modeling and design optimization of reclaimed asphalt pavement containing crude palm oil using response surface methodology

This study discusses the influence of using crude palm oil in hot mix asphalt incorporating recycled asphalt pavement materials. The effect of different percentages of recycled asphalt pavement (RAP) and crude palm oil (CPO) on stability, flow, stiffness, voids in mix (VIM), voids filled with asphalt (VFA), and Indirect Tensile Strength (IDT) were assessed. In addition, for the statistical analysis an analytical tool response surface methodology (RSM) was used for designing and statistically analyzing the experimental results. A microstructure level investigation on the virgin binder (60/70) and RAP binder incorporating crude palm oil was performed using atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) analysis. Experimental results showed that stability and indirect tensile strength increases with an increase in recycled asphalt pavement material up till 80%. However, 100% RAP with crude palm oil resulted in reduction in these strength parameters. The microstructural analysis shows that the incorporation of CPO in virgin and RAP aged binder change the structure of aged and virgin binder by new and unique phase formations. The statistical models were found significant and well fitted on bases of R2 value (>0.80), high adequate precision value (>4), low p-value and insignificant lack-of-fit. Furthermore, ANOVA model theoretical results by the RSM analysis were validated by experiments with <5% of error that represent a good agreement between experimental and theoretical results. Crude palm oil inclusion in HMA-RAP showed good improvement in performance parameters indicating a potential source of rejuvenating agent as bio binder material for the pavement construction industry.

Using steady shear rate sweep protocol to determine zero shear viscosity of unaged and aged unmodified bituminous binders

Rutting is one of the most significant distresses occurring in bituminous pavements at higher pavement temperatures. Researchers have been focusing on developing bitumen binder parameters that can be used to predict the rutting resistance of bituminous mixtures, and zero shear viscosity (ZSV) has proven its efficacy as a binder rutting parameter. A stepwise steady shear rate sweep test with two cycles of forward and backward sweeps was conducted at very low shear rates to determine the ZSV of unaged, short-term aged, and long-term aged unmodified bitumen binders. Convergence of the steady-state viscosities was observed at different shear rates in the first forward sweep. The response of the binders was independent of the shear rate, time, and the effect of shear history was negligible. As the shear rates corresponded to the ZSV regime, the ZSV was determined from the first forward sweep. The ZSV correlated well with the three existing rutting parameters.

Experimental investigation on the influence of interfacial effects of limestone and fly ash filler particles in asphalt binder on mastic aging behaviors

The incorporation of mineral filler has significant influence on the rheological response of asphalt binders over oxidative aging. This study focuses on understanding the physicochemical interaction of filler particles (i.e., fly ash and limestone) to asphalt binders and how fillers affect oxidative aging of binder by using Atomic Force Microscopy (AFM) and Fourier Transform Infrared (FTIR). The microstructural and chemical characteristics regarding base asphalt as well as different asphalt adsorbed films of fly ash and limestone asphalt mastics were obtained before and after aging process via AFM and FTIR, respectively. The results show that significant differences in terms of surface morphology were obtained for binders with different fillers. The typical “bee-like” structure was not found but instead “flake-like” or round shape dispersed phases appeared on the surface various asphalt adsorbed samples. As approaching the filler surface, the size and number of these dispersed phases changed under the asphalt -filler interaction effect. The infrared peaks of carbonyl and sulfoxide bands are used to evaluate the extent of oxidative aging. Compared to the base asphalt, the oxidation resistance of binder was improved by adding fly ash and limestone filler. Moreover, the IC=O and IS=O aging indexes of each asphalt adsorbed film of fly ash asphalt mastics were lower than that of corresponding sample of limestone asphalt mastic.

Anti-aging additives: proposed evaluation process based on literature review

Asphalt binder ageing alters its chemical and physical properties in a manner to make it brittle and more susceptible to thermal and fatigue cracking. The ageing rate of asphalt binders depends on a combination of different factors related to their chemical composition, environmental conditions and mix design. In order to prevent ageing, anti-ageing additives are used. The selection of the optimal additive should follow an iterative process. The additive choice is made concerning each case studied. Then, the selected modified asphalt binder is short-term aged by RTFOT and long-term aged by PAV and ultraviolet (UV) weathering. Rheology performance parameters are measured by DSR and BBR before and after ageing. Consequently, ageing indices are calculated to evaluate the appropriateness of the additive. The paper discusses several findings on the rheological level accordingly to the literature. Finally, a process is proposed to harmonise the research and the engineering practices in studying anti-ageing additives effects on asphalt binders.

Towards an understanding of diffusion mechanism of bio-rejuvenators in aged asphalt binder through molecular dynamics simulation

The use of reclaimed asphalt pavement (RAP) is a hot research topic in the field of road engineering, as there are still many issues to overcome so as to become standard engineering applications. The diffusion of virgin/aged asphalt binder is a key process to improve RAP performance. In this study, the asphalt binder diffusion models were developed by molecular dynamics (MD) simulation. Two kinds of bio-rejuvenators (BR-1 and BR-5) were chosen to represent the straight-chain and aromatic structures, respectively. The method of relative concentration, radial distribution function (RDF), and microstructure morphology were used to evaluate the effect of bio-rejuvenators on the diffusion process of virgin/aged asphalt binder. The results showed that bio-rejuvenators had a positive effect on the fusion process between virgin and aged asphalt binder. The volume diffusion coefficient based on asphalt binder diffusion models indicated that the bio-rejuvenators accelerated the fusion process between the virgin and asphalt binder. After adding bio-rejuvenators to the aged asphalt binder, the agglomeration intensity in the SARA fractions was reduced to different degrees. Due to the aging of asphalt binder, asphaltenes formed different types of micro-stacking phenomena such as “T-shaped stacking,” “Face to Face stacking,” and “Offset Face to Face stacking.” The bio-rejuvenators of BR-1 and BR-5 exerted different regenerative effects during the diffusion process of aged asphalt binder. For BR-1, the “Pull-Out” and “Intercalation” effect can be observed in the process of asphaltene deagglomeration. “Pull-Out” is the main regenerative effect of BR-5 in aged asphalt binder. A strong electrostatic interaction occurs between BR-5 and PAHs in asphaltenes. Thus, BR-5 achieves the goal of aged asphalt binder regeneration by attracting PAHs.

Methods for Studying Aging of Polymer Binders

Methods for Studying Aging of Polymer Binders

Studying the Effect of Syrian Natural Zeolite On Properties of Asphalt Binder

In the last years, many researchers studied production of warm asphalt concrete by usingorganic, chemical and water-bearing additive )synthetic zeolite). The purpose of this research is to study theeffect of Syrian natural zeolite on the physical and rheological properties of asphalt binder and verify ofusing it to produce warm asphalt concrete (as a binder modifier or as additive to asphalt concrete), in additionto economic benefits by saving on the cost of synthetic zeolite. In this study, natural zeolite characterizationhas been investigated via X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD) and Thermal Gravimetricanalysis (TGA). Natural zeolite was added to asphalt binder with different percentages (3, 4, 5 and 6%) byweight and to determine the effect of natural zeolite on properties of asphalt binder, penetration at )25(°∁,softening point, ductility, viscosity at (110, 120, 135)°∁ and RTOFT tests were carried out on both modifiedand unmodified aged asphalt binder with natural zeolite. According to the test results, it has been seen thatthe addition of natural zeolite improves properties of the asphalt binder and an increase in its resistance tofatigue, and do not make a substantial difference on the workability of the asphalt binder. So the effect ofthe mixture of natural zeolite additives on the workability could not be predicted on asphalt binder, thereforethe direct effect of additives should be studied on the asphalt mixtures.

Evaluation of mix design volumetrics and cracking potential of foamed Warm Mix Asphalt (WMA) containing Reclaimed Asphalt Pavement (RAP)

ABSTRACT In this study, the mix design volumetrics and cracking potential of foamed Warm Mix Asphalt (WMA) containing various amounts of Reclaimed Asphalt Pavement (RAP) were evaluated. It was found that the increased coating ability of the foamed WMA binder counteracted the lowering of mixing and compaction temperatures for WMA. Therefore, both control HMA and foamed WMA exhibited similar mix design volumetrics up to certain lower temperatures. However, further reductions in the mixing and compaction temperatures for foamed WMA were found to exhibit improper mixing between aggregates and foamed binder. Despite foamed WMA exhibiting similar volumetric properties as HMA up to certain lower temperature, their fatigue cracking performance was found to be significantly different. The foamed WMA was found to exhibit higher cracking resistance compared to HMA in Louisiana Semi-Circular Bending (SCB) and Illinois Flexibility Index Test (I-FIT) tests. A similar trend in the cracking resistance was observed for coarser mixes in the Abrasion Loss Test (commonly known as Cantabro test). However, the Cantabro test could not screen finer mixes for their cracking resistance as it lacks a mechanistic basis. Finally, the foamed WMA technology was found to increase the cracking resistance of asphalt mixes. The higher RAP content in the foamed WMA, on the contrary was found to lower the cracking resistance of asphalt mixes due to incorporation of aged and stiffer binder from RAP.

Evaluation of waste engine oil rejuvenation for highly short term aged asphalt binder

ABSTRACT The ageing property of the asphalt binder is time-dependent. A time-dependent short term ageing property of 80/100 penetration grade bitumen and the possibility of waste engine oil rejuvenation for the highly aged asphalt binder performance were investigated. Four specimens of equal weight from the penetration grade-80/100 bitumen are collected. The first specimen was checked for quality requirements. The other three specimens were aged using rolling thin film oven for 85, 115, and 145 minutes to simulate the delay during hot mix asphalt production, hauling, and compaction. The highly aged bitumen was rejuvenated with 2%, 5%, and 10% Waste Engine Oil by weight. Results indicated that as the ageing time increased, penetration and ductility decreased, softening point, flash point, fire point, and mass loss increased. A conventional test showed that highly aged bitumen from the trial period was 145 minutes and 10% waste engine oil obtained the optimum dosage. Further, multiple stress creep recovery analyses indicated the rejuvenated binder is prone to pavement rutting above 70°C, and rejuvenation is effective for pavement temperature below 70°C. Hence, exposing the asphalt binder for temperature for a more extended period affects pavement performance.

Performance of Aged Asphalt Binder Treated with Various Types of Rejuvenators

High demand for asphalt binders in road construction verifies the need of finding alternative materials through asphalt pavement recycling. This paper investigated the impact of different rejuvenators on the performance of an aged asphalt binder. Virgin Olive oil, virgin cooking oil, waste cooking oil, virgin engine oil, and waste engine oil were added to a 30/40 penetration grade aged asphalt binder at a fixed oil content of 4% for all types. The wet method was used to blend the rejuvenators and aged asphalt binder. The physical, rheological, and chemical properties of the rejuvenated asphalt binder were evaluated using several laboratory tests which include penetration, softening point, bleeding, loss on heating, storage stability, penetration index, ductility, viscosity, dynamic shear rheometer, and Fourier transform infrared spectroscopy. The outcomes of the physical properties showed that the olive, waste, and virgin cooking rejuvenators can restore the aged asphalt binder to a penetration grade of 60/70. In contrast, the virgin and waste engine oil required a more quantity of oil to rejuvenate the aged asphalt binder. A sufficient amount of rejuvenator could regenerate the (G*/sin δ), (δ°), and (G*) for the aged asphalt binder. The addition of virgin olive and cooking oils in aged asphalt led to a rutting issue. No chemical reactions were observed with the addition of rejuvenators but they give an impact on reducing the oxidation level of the aged asphalt binder. As a result, further research should be performed on waste cooking oil given that it is inexpensive and provides excellent performance results. Doi: 10.28991/cej-2021-03091669 Full Text: PDF

Environmental impact of rejuvenators in asphalt mixtures containing high reclaimed asphalt content

ABSTRACT The use of reclaimed asphalt pavement (RAP) is of increasing importance due to fast-growing amounts of demolished road materials. However, reclaimed asphalt can contain relevant amounts of pollutants such as carcinogenic polycyclic aromatic hydrocarbons (PAHs) and toxic metals. In order to improve the mechanical properties of recycled asphalt, rejuvenators are used to reduce the stiffness of the aged binder. These rejuvenators in turn may potentially mobilise pollutants like PAHs and facilitate their leaching to surface and ground waters. The environmental impact of three rejuvenators with good mechanical performance was studied. The environmental impact was assessed by determining metal- and PAH contents in the RAP and in leachates. Chemical analyses showed that rejuvenators did not mobilise PAHs from RAP materials for 2–3 ring PAHs. However, some 4–6 ring PAHs that are relatively less toxic indeed leached more easily from unaged material. Ageing reduced the tendency for PAH leaching, without and with rejuvenator.

Assessment and Modeling of Aging Effect on Asphalt Material Dynamic-Mechanical Properties

Abstract In this study, the effects of progressive aging on the dynamic-mechanical characteristics of asphalt and asphalt concrete were assessed and evaluated. Field-collected asphalt-aggregate mixture was used to prepare asphalt concrete test specimens. These specimens were then subjected to five aging levels and tested for dynamic-mechanical properties in the laboratory. Results showed that the dynamic-mechanical characteristics of asphalt concrete are significantly affected by progressive aging. In addition, aged asphalt binders that corresponded to the asphalt concrete samples aged at various aging levels were tested for complex shear modulus using a dynamic shear rheometer. A significant effect of progressive aging on the complex shear modulus and viscosity of the binder was observed. A detailed assessment showed that even though the mechanical behavior of asphalt binder significantly changes because of aging, the corresponding asphalt concrete sample does not necessarily show similar change in its behaviors. Finally, this study developed an approach to estimate the dynamic-mechanical characteristics of the aged asphaltic materials. Using this approach, it may be possible to predict the mechanical behaviors of aged asphalt concrete and binder. It is hoped that the developed approach can be useful for advanced modeling of asphalt pavements.