Pavement Binder Research Articles

Hydrothermal liquefaction bioproduct of food waste conversion as an alternative composite of asphalt binder

Considerable environmental concern regarding increased food wastage caused by population and economic growth has been raised worldwide. The verification of food waste recycling product for engineering purposes is also vague. This work evaluates a liquefied bio-product recovered from the hydrothermal liquefaction of food waste as a potential non-petroleum-based binder in asphalt pavement. Various parameters were evaluated to optimize the liquefaction reaction for the enhancement of the liquefied food waste (LFW) product recovered from the process. The LFW was characterized for chemical compound and used to substitute different portions of conventional asphalt binders 60/70 pen (i.e., 10%, 20%, and 30%) from the total binder weight. The conventional and modified asphalt binders were evaluated for storage stability, physical and chemical properties, thermal decomposition, and functional groups. Thermal degradation affirms the presence of LFW in the modified asphalt, and the low molecular weight concerning high-boiling point compounds were identified. The use of LFW in the asphalt binder produces a modified binder with physical properties and storage stability that are comparable with those of petroleum-based asphalt, thereby suggesting that the liquefied product obtained from food waste can be used as bio-binder in asphalt pavement.

Rheological and physico-chemical properties of warm-mix recycled asphalt mastic containing high percentage of RAP binder

Abstract The present study investigated rheological and physico-chemical properties of warm-mix recycled asphalt mastics containing a high percentage (50%) of artificial reclaimed asphalt pavement (RAP) binder. The influence of two typical warm-mix additives (a wax-based R and a surfactant-based M), four mass ratios of filler to asphalt (0.0–1.5), and three aging states (unaged, short-term aged and long-term aged) was evaluated through the dynamic shear rheometer (DSR), bending beam rheometer (BBR), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) tests. A total of 48 different mastics were tested and analyzed. The results showed that both the increasing RAP binder and filler contents had a stiffening effect on the asphalt mastics over the full range of testing temperatures and significantly reduced the linear viscoelastic strain limits of the mastics. The two warm-mix additives played quite different roles in changing the rheological properties of the mastics. Overall, the addition of the wax-based R exhibited a softening effect on the mastics and thus was capable of offsetting the stiffening effect of applying the RAP binder and mineral fillers; whereas the impact of the surfactant-based M on the rheological properties of the mastics was found negligible. The difference of R and M in working mechanisms could be clearly characterized using the chemical FTIR spectra.

Effect of Recycled Asphalt Pavement Binder on Rheology of Crumb Rubber–Modified Binder—An Experimental, Analytical, and Analogical Study

Abstract The popularity of recycled asphalt pavement (RAP) is on the rise because of the benefits of sustainability. In an unavoidable scenario wherein crumb rubber–modified binder (CRMB) is adopted as a base binder in RAP mixes, the binder from RAP will blend with CRMB, thereby influencing its rheology and performance at high, intermediate, and low temperature. Hence, in this study, binder extracted from two RAP sources (RAP X and RAP Y) was blended with CRMB at varying proportions of 15, 25, and 40 % by weight. Isochronal temperature sweeps, isothermal frequency sweeps, and bending beam rheometer tests were conducted on the prepared blends. Thereafter, analytical and analogical studies were performed using master curve construction, 2S2P1D, and Huet modelling. The results indicated that RAP from different sources affects the high-, intermediate-, and low-temperature performance of CRMB. Different RAPs were observed to have contrasting effects on high-temperature performance grading. Intermediate-temperature performance based on cross-over temperature (TCROSS-OVER) indicated a compromise because of the inclusion of RAPs. An evaluation of the differences among critical temperatures at low temperature (ΔTc) indicated the degradation of low-temperature performance. Such changes in high-, intermediate-, and low-temperature performances were validated by complex modulus (G*), stiffness (S(t)), and stress relaxation (E(t)) master curves. Finally, the 2S2P1D and Huet model were observed to depict reasonably good fits for the prepared blends. This study concludes that RAPs from different sources have contrasting impact on CRMB and may adversely impact the intermediate- and low-temperature performance.

Effects of Human Hair Additives on Strength of Asphalt as Potential Binder in Flexible Pavement

Effects of Human Hair Additives on Strength of Asphalt as Potential Binder in Flexible Pavement

Multi-Walled Carbon Nanotubes Enhanced the Performance of Epoxy Asphalt Pavement Binder

Modifying epoxy asphalt with nanomaterials is an effective method to enhance the performance of epoxy asphalt binder. The carbon nanotubes were modified and carbon nanotubes/epoxy asphalt (CNTs-EA) was fabricated by mechanical stirring. The performanceof CNTs-EA pavement binder (CNTs-EAPB) was analyzed by immersion marshall's, freeze-thaw splitting and dynamic stability tests. Experimental results showed that the dynamic stability and freeze-thaw splitting intensity of matrix asphalt binder (MAB) were improved by 118.6% and 85%, respectively. While the dynamic stability of CNTs-EAPB remained 90.8% under soaking water which was more than 77.44% of matrix asphalt and reached 5801 times per mm. This enhancement is mainly attributed to excellent characteristics of CNTs as well as the effective synergistic effect between CNTs and epoxy resin.

Evaluation and classification of recycling agents for asphalt binders

The economic and environmental benefits of using recycled asphalt materials continue to motivate agencies to increase their proportion in new pavement construction and maintenance and rehabilitation activities, but the resulting reduced cracking resistance remains an engineering performance challenge. The addition of recycling agents is one of the strategies to mitigate this issue caused by the increased stiffness and brittleness of the recycled mixture. This study explored the mechanism by which different types of recycling agents partially restore flexibility and ductility of asphalt binder and mixtures. A binder blend with 50% reclaimed asphalt pavement (RAP) binder was rejuvenated with seven types of recycling agents. Rheological and chemical tools were used to evaluate the binder blends and compare their performance to a control blend without a rejuvenator to study the rejuvenation mechanism. Corresponding asphalt mixtures were also tested to ensure adequate performance. Based on the results, the recycling agents were divided into three categories: (a) Softeners, (b) Replenishers, and (c) Emulsifiers. The results showed that while some agents act only on a physical level, others interact with the blend at a chemical level that affects the physical properties. A novel parameter was developed to compare the effectiveness of various recycling agents.

Effect of Various Additives on the Low Temperature Performance of Petroleum Based Asphalt Binders

Transverse cracking is a prevalent problem that occurs in asphalt pavement binders in cold climates and diminishes the integrity of the road as well as shortens the life span of the road leading to premature failure. Current specification for testing petroleum asphalt binders for transverse and low temperature cracking is not elaborate enough to accurately model the engineering behaviour of the binders. Besides, neat asphalt derived from petroleum crude oil does not seem to perform well at certain low temperatures without some modification to it. Thus, a study was to be undertaken to determine the low temperature behaviour of 60-70 penetration neat binder modified with traditionally used materials such as Crushed Lime Stone Powder (CLP), Hydrated Lime (HL) and Cellulose Oil Palm Fiber (COPF) at temperatures 0 °C, -5 °C and -10 °C. The study was carried using the state of the art Bending Beam Rheometer (BBR) to assess the stiffness value, m-value and deflection level. The tests were performed in accordance with AASHTO T 313-12 specification. The results of the penetration, rotational viscosity and softening point showed that all of the modified binder specimens are within the required range. However, the performance assessments on the modified petroleum binders with additive materials showed a varied nature with CL powder being the best and the COPF the lowest. It was also observed that the crushed lime stone powder had an increase in stiffness, reduction in deflection and m-value.

Rheology of Virgin Asphalt Binder Combined with High Percentages of RAP Binder Rejuvenated with Waste Vegetable Oil.

Waste cooking oils (WCOs) show promise as a rejuvenator for reclaimed asphalt pavement (RAP) binders. Their use helps to make RAP a renewable resource and to address environmental concerns related to WCO disposal. While studies suggest that 100% RAP for pavement is feasible, RAP will likely be combined with a virgin binder and aggregate incrementally in the field. In this study, the rheological properties of the virgin binder blended with a simulated RAP binder and 10% waste vegetable oil (WVO) as a rejuvenator were examined. Viscosities below that of a PG 64-22 virgin binder were observed with WVO in blends of 40 or 60% RAP and the virgin binder. The virgin-60% RAP/WVO binder blend retained a Superpave grade of the virgin binder and was found to satisfy requirements for both rutting parameter and fatigue resistance. Results indicated that WVO significantly reduced the effects of long-term ageing, making the blend containing RAP durable. The effect of RAP content on WVO/virgin binder blends was most pronounced on the rutting parameter. A “molecular lubrication” model is suggested as a mechanism for the viscosity reduction with WVO.

A blending efficiency model for virgin and aged binders in recycled asphalt mixtures based on blending temperature and duration

The degree of blending of reclaimed asphalt pavement (RAP) binder is profoundly influencing the performance of asphalt mixtures containing RAP. Hence, it is essential to know the amount of RAP binder mobilized into the mixture to produce more durable asphalt mixtures. However, understanding the factors affecting the degree of blending and quantifying the degree of blending is still an open problem for researchers. This study investigates the effect of several factors such as blending method, blending temperature, blending duration, and RAP content on the degree of blending using Fourier Transform Infrared Spectroscopy (FTIR) analysis of the extracted binder from mixtures. It is revealed that the blending method, blending temperature, and blending duration have a significant influence on the degree of blending. The study revealed that prolonged blending durations and elevated mixing temperatures could improve the degree of blending. The amount of RAP in the mixture has little or no influence on the degree of blending. Further, based on the results, a blending chart is developed to determine the degree of blending with regard to blending duration and blending temperature.

ANALYSIS OF POSSIBILITIES OF USING PHOSPHOLIPIDES TO INCREASE THE ADHESIONAL ABILITY OF ROAD BITUMEN

The article is devoted to the issue of increasing the adhesive ability of road bitumens. The aim of the work is to show how oxidized phospholipids affect the adhesion of bitumen on the basis of studying the adhesion properties of road bitumens, as well as research. Laboratory experiments have shown that the addition of phospholipids to road bitumens has significantly increased flash point, softening temperature and adhesion, which makes this additive promising for improving the quality of bitumen as a binder for pavements. Experimental studies allow to evaluate of road bitumens; efficiency and optimal modes of using phospholipid concentrate; summarize the results obtained and assess the feasibility of using phospholipid concentrate in the process studied. It is established that a significant rank correlation is observed between the standardized indicators of the quality of bitumen being considered.

Relationship between nonlinear viscoelastic behaviour of asphalt binders and deformation of mixtures

ABSTRACT Ranking of asphalt binders based on the permanent deformation characteristics of the respective mixtures is important for designing mixtures for pavements. While various tests on binders and corresponding parameters have been suggested for ranking asphalt binders, their applicability is limited since many of these parameters fail to characterise the nonlinearity in the response of asphalt binders at high stress levels and shear rates. Parameters like the non-recoverable creep compliance () from MSCR tests and the apparent viscosity from the steady shear tests are some of the few parameters that take into consideration the nonlinear viscoelastic nature of asphalt binders. However, these parameters should be determined at an appropriate stress level or shear-rate level that is representative of the stress/shear-rate level experienced by binders in pavements. In this study, the stress/shear-rate levels suitable for obtaining and apparent viscosity were determined by characterising flow behaviour of binders and their corresponding mixtures. Three asphalt binders were used in the study. The binders were characterised by conducting creep-recovery and steady shear tests, and fitting a nonlinear viscoelastic model to the results. The permanent deformation of the corresponding asphalt concrete mixes in two different tests- dry wheel tracking test and repeated creep and recovery test were obtained from another study. It was observed that the apparent viscosity determined over a stress range and a shear-rate range correlated well with the rate of permanent deformation observed in the mixture characterisation tests.

Using bio-oils for improving environmental performance of an advanced resinous binder for pavement applications with heat and noise island mitigation potential

Urbanization and actions are responsible for overheated cities compared to the adjacent rural settings, a phenomenon known as Urban Heat Island (UHI). Additionally, conventional urban materials contribute towards the aggravation of urban noise pollution, a phenomenon that may be described as Urban Noise Island (UNI). Numerous solutions have been proposed through the implementation of novel, more sustainable, or natural materials in the pavement infrastructure. To that end, this study bridges the gap between UHI and UNI mitigation strategies, simultaneously ensuring low environmental impact. Therefore, a resin-based pavement binder was investigated through multiphysics analysis, together with four innovative binders made with waste bio-oils. Thermal, optical, acoustical and Life Cycle Assessment analysis were carried out for gauging the UHI/UNI mitigation potential of binders and their environmental impact. Results showed that the innovative binders preserved good physical properties: all binders have solar reflectance higher than 50% within 750–1600 nm range and sound absorption coefficient higher than 0.8 within 600–800 Hz. Additionally, bio-oils decreased the environmental impact of the binder up to 37.46mPt, and 8.33% in the ReCiPe, and Intergovernmental Panel on Climate Change analysis, respectively. Therefore, the exploitation of bio-oils in the pavement market can be considered as promising green solution for mitigating both UHI and UNI.

Effect of Cereclor as Rejuvenator to Enhance the Aging Resistance of Reclaimed Asphalt Pavement Binder.

Asphalt is the most commonly used material for pavement construction around the world, and therefore, it is vital to acquaint a practice that restores the reclaimed asphalt pavement (RAP) binder properties to the required level of performance by adding proper rejuvenators. However, a rejuvenator may perform better in the early stages of its application but may not necessarily perform better in the long run. The aim of this study is to assess the rejuvenation effect on the aging resistance of RAP binder in long-life performance through applying artificial aging. In this study, base virgin binder of pen grade 60/70 and RAP binder rejuvenated with Cereclor were subjected to artificial aging to simulate the short- and long-term aging effects. Penetration, softening point, ductility, and viscosity; saturates, aromatics, resins, and asphaltene (SARA) fractionation; and Fourier-transform infrared (FTIR) spectroscopy, bending beam rheometer (BBR), and dynamic shear rheometer (DSR) tests were conducted to evaluate the potential improvements in various properties of RAP binder. The results indicated that the physical, fractional composition, rheological, and aging resistance of RAP binder improved through the rejuvenation mechanism. Therefore, the rejuvenator improved the chemical structure through re-balancing the constituents in the colloidal system, even after long-term re-aging, which proves it to be an aging-resistant binder. Furthermore, it has been concluded that Cereclor has substantial rejuvenation potential even after applying artificial aging, and it can be utilized in pavement recycling to achieve long-life performance. Furthermore, the results depict good correlations between the physical, rheological, and chemical parameters of virgin and RAP binder.

Towards the Use of Waste Pig Fat as a Novel Potential Bio-Based Rejuvenator for Recycled Asphalt Pavement.

This article presents a novel potential bio-based rejuvenator derived from waste pig fat (WPF) for use in recycled asphalt applications. To achieve this purpose, the impact of different doses waste pig fat (e.g., 0, 3, 6, and 9 wt.% WPF) on the reclaimed asphalt pavement binder (RAP-B) performance is investigated. The unmodified and WPF-modified asphalts are characterized by means of Fourier-transform infrared spectroscopy (FT-IR), thin-layer chromatography–flame ionization detection (TLC-FID), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Physico-rheological properties of asphalt blends are assessed through Brookfield viscometer, softening point, penetration, and dynamic shear rheometer (DSR) tests. TLC-FID data highlighted that incremental WPF addition into RAP-B restored its original balance maltenes-to-asphaltenes ratio; finding which was supported by FT-IR analysis. SEM disclosed that WPF has a great compatibility with the aged asphalt. AFM observations showed that grease treatment induced a decline in surface roughness (i.e., bee structures) and a rise in friction force (i.e., para-phase dimension) of RAP binder. TGA/DSC studies revealed that the bio-modifier not only possesses an excellent thermal stability but also can substantially enhance the binder low-temperature performance. Empirical and DSR tests demonstrated that WPF improved the low-temperature performance grade of RAP-B, reduced its mixing and compaction temperatures, and noticeably boosted its fatigue cracking resistance. The rejuvenation of aged asphalt employing WPF is feasible and can be an ideal approach to recycle both of RAP and waste pig fats.

Study on a thermosetting polyurethane modified asphalt suitable for bridge deck pavements: Formula and properties

High-cost and unsatisfactory flexibility generally reduce the application possibility of epoxy asphalt binders in bridge deck asphalt pavements. To solve these defects, a novel idea that develops a thermosetting polyurethane (TS-PU) modified asphalt binder is put forward in this work. First, the appropriate formula of the TS-PU modified binder is determined via a series of laboratory tests. The comprehensive properties of asphalt binders containing various TS-PU contents are then investigated. Finally, a performance comparison is made between the TS-PU modified binder (with the optimum TS-PU content), styrene-butadienestyrene (SBS) modified binder and epoxy modified binder. Results show that, the addition of TS-PU improves the high temperature and mechanical properties while impairs the low temperature property of base binder. It is also demonstrated in this study that, the TS-PU modified binder is much better in high temperature rutting resistance and tensile strength than SBS modified binder; meanwhile, the TS-PU modified binder, on the whole, has an advantage over epoxy modified binder in flexibility and cost saving, showing a favorable application prospect in bridge deck pavements.

Effect of Using Rejuvenators on the Chemical, Thermal, and Rheological Properties of Asphalt Binders

Rejuvenators are used to restore the properties of reclaimed asphalt pavement (RAP) binders through readjusting the balance between the asphaltene and maltene fractions. To properly understand the ...

Rutting and fatigue performance evaluation of warm mix asphalt mastic containing high percentage of artificial RAP binder

This study investigated the rutting and fatigue performance of asphalt mastics containing high percentage of artificial reclaimed asphalt pavement (RAP) binder and two types of warm mix asphalt (WMA) additives, R and M. The filler/asphalt ratio (F/A) ranged from 0.0 to 1.5 and the recycled asphalt binder was blended with 50% artificial RAP binder. The Superpave high-temperature performance grade test and multiple stress creep recovery (MSCR) test were carried out to evaluate the rutting resistance of recycled asphalt mastic. An approach to determine the optimum filler/asphalt ratio was also proposed based on the MSCR parameter Jnr-diff. The fatigue performance under strain-controlled and stress-controlled load modes was investigated by linear amplitude sweep (LAS) test and time sweep test. It was found that artificial RAP binder, WMA additive M and mineral fillers could improve the high-temperature performance while the incorporation of WMA additive R would offset the advantage of artificial RAP binder in rutting resistance. The fatigue test results indicated that the effects of artificial RAP binder, WMA additives and mineral fillers on the fatigue cracking resistance of asphalt mastic exhibited different dependencies on the load mode. Besides, the energy-based approaches might be more acceptable for evaluating the fatigue life of asphalt materials according to time sweep test results.

Surface nanomechanical properties of bio-modified reclaimed asphalt binder

In this work, three different bio-based rejuvenators were added to the reclaimed asphalt pavement (RAP) binder: a vegetable oil, a cashew nut shell oil and a tall oil. To better understand the microstructural morphology, atomic force microscopy (AFM) was used before and after aging. Quantitative nanomechanical mapping (QNM) showed how the addition of rejuvenators affected the surface elastic moduli of RAP. Changes of the microstructure in modified RAP binders as a function of aging treatments were seen. Generally, the microstructures show four domains topographically, while two distinct domains are present in the phase image. It has been observed that these two different domains correspond to zones with different mechanical properties. Comparison between the “bees” surface’s elastic moduli and the bulk elastic moduli for a virgin bitumen showed that surface’s moduli were consistently higher than the bulk moduli contributing to the formation of the “bee” structures. “Bees” were observed to be composed of periodic ripples with a wavelength in the order of 400 nm for the aged virgin binder and 600 nm for the unaged one while amplitude equal to 8 and 15 nm for the aged and unaged case respectively. The results presented in this paper contribute to an improved understanding of the link between surface and bulk properties of bitumen.

Nonlinear Modeling of Nanoscaled Properties of Asphalt Binders Recovered from Weathered Asphalt Mixtures

AbstractIt is important to investigate the aging mechanism of asphalt binders. To simulate the aging of the binders in asphalt pavements, three mixture gradations of Stone Mastic Asphalt (SMA)-13, ...

Influence of chemical characteristics of RAP binders on the mechanical properties of binders and mixes

Utilization of reclaimed asphalt pavement (RAP) materials in the asphalt layer construction has emerged as an important rehab ilitation option for asphalt pavements. The properties of reclaimed asphalt material will be different from those of the initial (virgin) asphalt mixture due to the aging of the binder. Resilient modulus is an important material parameter used for the design of pavements. The mechanical behaviour of the mix and the binder is expected to be influenced by the chemical composition of the binder. In this study, the effect of the chemical composition of virgin and reclaimed asphalt pavement (RAP) binders on the resilient modulus (Mr) of RAP mixes has been evaluated. This is done by testing different RAP mixes prepared using bitumen samples containing different proportions of RAP binder. The RAP mixes prepared using one aggregate gradation (mid-point gradation recommended by the Ministry of Road Transport and Highways for Bituminous Concrete -1) and different RAP contents (0, 15, 25, 35 and 45%) with VG-30 as virgin binder, were tested for their resilient modulus values at different temperatures (15, 25 and 35°C) and frequencies (0.5, 1, 1.5 and 2 Hz). The chemical composition of the binder blends was evaluated with the help of Fourier transform infrared spectroscopy (FTIR). The relationship between the chemical indices and the rheological parameters has been examined. Ketones, aliphatics and aromatics are found to have good correlation with rheological properties. The chemical indices also are found to have good correlation with the resilient moduli of the mixes.