Virgin Binder Research Articles

Validation of a sieve analysis procedure to quantify reclaimed asphalt pavement (RAP) binder availability

ABSTRACT Recycled binder availability (RBA) refers to the proportion of total recycled binder that is available to blend with virgin asphalt binder and is considered an inherent property of a given reclaimed asphalt pavement (RAP) stockpile. Recycled binder contribution (RBC) is the fraction of the recycled asphalt binder that is incorporated into the virgin binder within an asphalt mixture. Binder that is inside agglomerated RAP particles that do not separate during the mixing process is ‘unavailable’. This study validates a method to quantify RBA through comparative sieve analysis of RAP and recovered RAP aggregate, testing two hypotheses: (1) RAP agglomerations preexist and don’t fully break during production, and (2) RBA measurements estimate RBC. The method was applied to nine RAP sources from four states. The innovation was verified to accurately reflect RBC in asphalt mixtures through comparative tracer-based microscopy. Results showed RBA and RBC typically between 50-60%, indicating not all recycled binder blends with virgin binder. Further analysis of mixtures fabricated with different preheating and conditioning procedures suggested that RBC doesn’t vary significantly with laboratory production conditions. Thus, RBA measurements from sieve analysis show promise in estimating RBC in asphalt mixtures across production conditions, supporting the study’s hypotheses.

Analysis of the Optimum Performance for Polymer and Polymer–Nanocomposite-modified Asphalt by Using Multicriteria Decision Analysis

The influence of Acrylate Styrene Acrylonitrile (ASA) and ASA/nanosilica (ASA/Si) additives was investigated by using a dynamic shear rheometer (DSR). Firstly, an ASA polymer was blended with the virgin asphalt binder at two different concentrations (3% ASA and 5% ASA). After observing that 5% ASA was the optimum concentration for modification, nanosilica particles were further incorporated into the 5% ASA-modified asphalt binder with two different percentages (5% ASA 3%Si; 5% ASA 5%Si). Frequency sweep tests were conducted across various frequencies at elevated temperatures. The experimental outcomes were analyzed using master curves, rutting, and fatigue resistance parameter plots. Additionally, to provide a more holistic analysis, two different multicriteria decision analysis (MCDA) techniques, namely the Preference Ranking Organization Method for Enrichment Evaluations (PROMETHEE) and the Technique for the Order of Preference by a Similarity to Ideal Solution (TOPSIS), were conducted to identify the best-performing asphalt binder by considering three different parameters: workability, performance under different conditions, and cost. The frequency sweep tests showed that the 5% ASA 5%Si asphalt worked best in terms of resistance to rutting. On the other hand, the virgin binder performed better than all modified binders when it failed to resist fatigue. On the other hand, the PROMETHEE analysis identified the 5% ASA-modified asphalt binder as the optimal choice, while the TOPSIS analysis determined that the 5% ASA 3%Si-modified binder provided the best performance. The differences between the experimental results and the MCDA were due to using more than one evaluation parameter and looking at how well the asphalt binder worked at different temperature ranges at the same time.

Effect of Chemical Composition on Rheological Properties of Asphalt Binders Modified with Rap Binders and Rejuvenator

Conventional rejuvenating agents such as virgin binders, polymers and so on, poses environmental, technical, and economic challenges. The objective of this study is to investigate the interaction between chemical components and rheological behavior of hot mix asphalt modified with RAP binder and diesel engine waste oil (DEWO) as rejuvenator. 7.2% DEWO was added to the RAP binder to achieve the modified binder (MB), and the effects of the rejuvenator through the MB were evaluated at varying percentages (0 to 100% by weight of the virgin binder) using Dynamic Shear Rheometer (DSR) under short and long-term aging at high and intermediate temperatures, as well as low temperatures using Bending Beam Rheometer (BBR). Saturates, aromatics, resins, and asphaltenes (SARA)-separation, Indirect tensile stiffness modulus test (ITSM), and fatigue life test were also employed to investigate the interaction between chemical components and rheological properties of binder. Results indicated that incorporating 50% modified RAP binder significantly enhanced the performance of the asphalt mixtures, it was also discovered that 100% of RAP content meets standard specifications when modified with oil rejuvenators. This research suggests that large quantities of diesel engine waste oil can be diverted from landfills and employed as useful resource in asphalt production.

Investigation of immobilized RAP binder on asphalt-asphalt/aggregate interaction under multiple temperatures

The traditional blending process includes blending recycled asphalt pavement (RAP) aggregates and virgin aggregates first and then adding the virgin binder. In the first blending process, the mobilized RAP binder coated virgin aggregates, and the immobilized RAP binder remained RAP aggregates. The objective of this study was to investigate the role of the immobilized RAP binder in the mixing process. The contact angle test and binder bond strength (BBS) test were utilized under multiple temperature conditions to discuss the interaction behavior between immobilized RAP binder and virgin binder/aggregate. Results showed that at 90–170 °C, the spreading degree and rate of contact angle between virgin binder and immobilized RAP binder was bigger and higher than that between virgin binder and virgin aggregate, which indicated that the contact behavior between virgin binder and RAP aggregate was stronger than that between virgin binder and virgin aggregate. But at 50–90 °C, the changes in contact behaviors were unstable and irregular. In BBS test, at 20–60 °C, the bonding strength between virgin binder and slate coated by immobilized RAP binder was higher than that between virgin binder and clean slate. At 0–20 °C, the BBS of former was slightly smaller than that of latter. It was believed that the immobilized RAP binder on the surface of RAP aggregate could promote more effective wetting effect between RAP aggregates and virgin binder during mixing, which was better than that between virgin binder and virgin aggregate.

Effect of Bio-Oils and Wastewater Sludge on the Performance of Binders and Hot Mix Asphalt with High Reclaimed Asphalt Pavement Content.

Waste Cooking Oil (WCO), Soy Oil (SO), and Wastewater Sludge (WWS) have great potential to increase reclaimed asphalt pavement (RAP) content for economic and environmental benefits. This study explored the effects of SO and WCO on rutting, fatigue cracking, and low-temperature cracking performance of binders and Hot Mix Asphalt (HMA) with high RAP content. The potential effect of WWS on the performance and compaction efforts of high RAP content mixes at a 10 °C (50 °F) lower compaction temperature than the control compaction temperature was also investigated. The results indicated that 85% of the RAP binders can be incorporated while maintaining similar performance compared to the control by using 15% SO or 12.5% WCO as a rejuvenator with 2.5% virgin binder. Adding 1% WWS by weight of the total binder improved the binder's rheological properties, the mix's cracking performance, and the mix's density at lower compaction temperatures.

Unveiling the composite rejuvenator efficacy on performance improvement of asphalt binder including high RAP contents

Since the incompatibility between crumb rubber (CR) and reclaimed asphalt binder (RAB) can cause sedimentation and limit its application, this study employed waste cooking oil (WCO) to pre-treat CR particles at different CR/WCO ratios, and assessed its impact on performance of asphalt binders including 30 % and 50 % RABs. Anti-aging and rejuvenation potentials of corresponding composite rejuvenators in binder blends were explored by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) tests, while the performance of corresponding binder blends was evaluated by bending beam rheometer (BBR), linear amplitude sweep (LAS), and multiple stress creep recovery (MSCR) tests. Furthermore, correlation analyses were performed to explore the relationships between the chemical and rheological parameters with a significance level below 0.05. The results confirmed the rejuvenation efficacy of composite rejuvenators in high RAB, and improvement in the critical low temperature of binder blends to a higher performance grade (PG) level compared to the non-treated CR modified binder. In addition, the fatigue cracking resistance was improved at the strain levels higher than 4 % in LAS test. However, the pre-swelled CR fairly compromised the rutting performance of binder blends compared to non-treated CR, its performance was still better than virgin binder. The correlation analysis suggested that it is possible to use chemical parameters as indicators for evaluating certain rheological properties.

Modeling and design optimization of the performance of stone matrix asphalt mixtures containing low-density polyethylene and waste engine oil using the response surface methodology

In recent years, the use of waste plastic materials such as low-density polyethylene (LDPE) to modify asphalt binders and enhance mixture performance has garnered significant attention. One major concern with using such materials is the higher production temperature required, which necessitates the use of a bitumen extender agent, such as waste engine oil (WEO), to reduce the viscosity and mixing temperature. Therefore, using these stabilizing additives can reduce the consumption of virgin binder, especially for Stone Matrix Asphalt (SMA) mixtures, which require higher asphalt content. This study aimed to optimize the design of SMA modified by LDPE and WEO to minimize the optimum asphalt content (OAC) and mixing temperature while maximizing SMA performance. To achieve this, Response Surface Methodology (RSM) was utilized to develop the necessary models for optimizing design and predicting performance. The selected independent variables (factors) for the design include LDPE content, WEO content, OAC, and mixing temperature. Meanwhile, the responses (dependent variables) consist of Marshall stability, rut depth, tensile strength ratio, and resilient modulus, which were used to determine the best mix design. The findings demonstrated that the suggested models for the output variables can predict performance with a higher level of confidence. The Analysis of variance (ANOVA) demonstrated that predictive models were significant and well-fitted, with a coefficient of determination (R2) of higher than 0.80, an adequate precision value of greater than 4, and a low p-value (less than 0.05). The error percentage between the RSM-predicted and actual values was less than 5 %, indicating that RSM-established models can accurately and efficiently predict the SMA performance. The best mix design of the SMA mixture modified by LDPE and WEO was found to be 10 % LDPE, 3.91 % WEO, 5.92 % OAC, and mixing temperature of 152.24°C with a combined desirability of 82.8 %.

From crude oil to bitumen: Genetic variability in chemistry and its influence on viscoelastic of binders

The chemical composition and properties of bitumen are derived from crude oil, which directly influences its viscoelastic properties. Six different crude oil sources were examined to explore how crude oil characteristics impact bitumen. The bitumen was produced through in-house atmospheric decompression distillation, and aging tests were conducted on these samples. The chemical properties of the crude oils, virgin binders, and aged binders were analyzed using Fourier Transform Infrared Spectroscopy (FTIR). Additionally, the separation and quantitative analysis of saturates, aromatics, resins, and asphaltenes (SARA) in crude oil and bitumen binders were carried out using Thin Layer Chromatography-Flame Ionization Detector (TLC-FID). Sweep tests on binders were conducted using a Dynamic Shear Rheometer (DSR). Master curves were created based on the CAM model and the 2S2P1D model to assess the dynamic viscoelastic properties of bitumen. The grey correlation method was employed to examine how bitumen chemical composition and properties affect its viscoelasticity. Results indicated that crude oil profoundly influences bitumen's chemical composition and properties. The functional group index and component content of bitumen are inherited from crude oil and are closely linked to the corresponding indices of crude oil. The functional group index, SARA, and colloidal stability coefficients of bitumen are intimately connected to the viscoelastic parameters of bitumen. The impact of the functional group index on the viscoelastic parameters is more pronounced than that of SARA content. This insight is crucial for guiding the selection of oil sources in bitumen production processes.

Prediction and modelling marshall stability of modified reclaimed asphalt pavement with rejuvenators using latest machine learning techniques

The primary problem with the experimental evaluation of Marshall stability (MS) of reclaimed asphalt pavement (RAP) is the inherent complexity and variability involved in the process. Traditional experimental methods for predicting MS can be time-consuming, labor-intensive, and costly. In the present research, an effort has been made to assess the most appropriate machine learning model for the prediction of MS of RAP. The study addresses the problem of accurately predicting MS by using a variety of input parameters derived from experimental work. The data for models was split in 7:3 for training and testing of models. Bitumen content (BC %), virgin binder percentage (VB %), virgin binder performance grade (VB-PG), RAP percentage (RAP %), RAP binder percentage (RAPB %), RAP binder PG (RAPB-PG), rejuvenator type (Rej type) and rejuvenator percentage (Rej %) were applied as input parameters for MS prediction. Several machine learning models including random tree (RT), M5P, Gaussian process (GP), support vector machine (SVM), and random forest (RF) were utilized for determining the most appropriate prediction model. Seven metrics were used for assessing the performance of these models, such as CC, MAE, RMSE, RA, RRSE, WI, and NSE. Based upon these metrics, the RF model is found to outperform the other applied models with the values of CC = 0.9959 and 0.9763, MAE = 0.3129 and 0.7847, RMSE = 0.3976 and 1.0492, RAE = 9.0062 and 21.8247, RRSE = 9.3624 and 23.6832, WI = 0.998 and 0.984 and NSE = 0.991 and 0.944 for training and testing stages, respectively. Also, box plots and sensitivity analysis confirm the superiority of the RF model over other models. Finally, the sensitivity analysis suggests the importance of bitumen content in the prediction of MS of reclaimed asphalt pavement modified with rejuvenators.

Evaluation of degree of blending and interaction between aged and virgin asphalt binders using rheological and fracture measurements

Evaluating the blending and interaction processes between aged and virgin asphalt binders is significant for enhancing the performance and longevity of asphalt pavements, particularly when using Reclaimed Asphalt Pavement (RAP). The primary aim of this research is to investigate the optimal conditioning time for diffusion process between virgin and aged binders. To simulate age-hardened RAP binder, asphalt binders were artificially aged in a forced draft oven at 163 °C for five hours, followed by additional aging at 85 °C and 110 °C over periods of 5, 7, and 10 days. The research assessed the degree of blending and interaction between aged and virgin binders in two phases using rheological and fracture measurements. In the first phase, the study explored the effects of various conditioning temperatures and durations (135 °C and 165 °C for 15, 30, and 60 minutes) on the diffusion and blending of the asphalt binders. Results indicated that the interaction between aged and virgin binders depends on the temperature and duration of conditioning; notably, complete blending was achieved at 165 °C after 60 minutes. The second phase investigated the impact of aged binder content on the rheological and fracture characteristics of the blended binders. Findings showed that fracture energy and peak load decrease with an increase in aged binder content. Specifically, increasing the aged binder content from 10 % to 30 % resulted in an approximate 23 % reduction in fracture-related parameters, while increasing the aged binder content from 50 % to 70 % led to an approximate 51 % reduction. Additionally, analysis of the complex shear modulus across different blends revealed an increase in modulus and high-temperature performance proportional to the percentage of aged binder, suggesting a hardening effect in the blended binder. Overall, this study underscores the significance of understanding the interactions between aged and virgin binders to optimize the diffusion and blending processes, ultimately enhancing the performance of asphalt pavements containing recycled materials.

Aging behaviors of asphalt binders rejuvenated by different chemical fractions from waste cooking oil

Waste cooking oil (WCO) can be recycled cleanly as the rejuvenating agent for aged asphalt, boosting the utilization of reclaimed asphalt pavement materials in road engineering. However, the sensitivity of asphalt rejuvenated by WCO to secondary aging is unknown, which has an impact on its durability in practical engineering. The objective of this work is to explore the aging behaviors of asphalt binders rejuvenated by different chemical fractions of WCO. The performance of different fractions of WCO before and after aging treatment was evaluated. The sensitivity to aging was discussed for rejuvenated binders with WCO’s fractions as rejuvenating agents including the differences in aging resistance between them and the virgin binder. The experimental results indicate that the aging resistance of WCO’s fractions depends mainly on their carbon chain length. The sensitivity of rejuvenated asphalt to aging depends strongly on the aging resistance of WCO’s fractions. Additionally, it is found that the resistance of rejuvenated binders to aging is better than that of the virgin binder because the WCO's fractions are less volatile than the original light components of the virgin binder. Therefore, substances with strong fluidity and weak volatility in WCO are the optimal candidates for rejuvenating agents of aged asphalt considering both the rejuvenation effect and the resistance to aging. The findings of the research contribute to the sustainability of road engineering.

Optimising the dosage of bio-rejuvenators in asphalt recycling: A rejuvenation index based approach

While significant research efforts have been devoted to the rejuvenation of aged bitumen using bio-rejuvenators, a universally recognised approach for dosage optimisation is still yet to be established. Aiming to develop standardised methods to determine the optimal dosages of six types of bio-rejuvenators, this study validated the use of a rheology-based rejuvenation index as a potential universal method. Rheological properties of rejuvenated binders, determined through frequency sweep tests, multiple stress creep and recovery tests, linear amplitude sweep tests, and bending beam rheometer (BBR) tests were carried out with the properties of virgin binder as reference targets. The results indicated that the applied rheology-based rejuvenation index is a feasible approach. This index can ensure improved low- and intermediate-temperature (fatigue) performance of aged bitumen while maintaining high-temperature performance within acceptable limits. Further characterisation of the binders by Fourier Transform Infrared Spectroscopy (FTIR) analysis suggested that the bio-rejuvenation processes will commonly only involve physical softening rather than a chemical reversal of ageing. Therefore, the use of chemistry-based indices is likely not feasible.

Mechanical Properties and Performance of Mixtures Containing a High Level of Recycled Materials That Are Designed Using Alternative Approaches

Using recycled asphalt material (RAM) in asphalt mixtures is very common among transportation agencies. With the recent development of balanced mix design methods, it is becoming more important to understand how to optimize mixture performance by offsetting the adverse effects of RAM. In this paper, mixtures from three different sources were adjusted according to the availability adjusted mix design (AAMD) and corrected optimum asphalt content (COAC) methods. Three control mixtures containing RAM, three mixtures containing no RAM, five mixtures designed according to the AAMD method (two of which had 50% reclaimed asphalt pavement content), and two mixtures adjusted using the COAC-based approach were evaluated. Both asphalt mixture performance tester experiments and index tests were used in this study to evaluate material-level indicators of cracking and rutting resistance. Additionally, pavement performance simulations were carried out using AASHTOWare Pavement ME and FlexPAVETM to assess how the observed material-level differences led to differences in structural-level pavement performance. Both the AAMD and COAC methods improved cracking measures. However, the results suggest that the additional virgin binder added through the COAC method without any adjustments to the aggregate structure can have negative consequences for the rutting performance measures. In addition, the mixture and pavement performance results suggest that the AAMD method is a rational approach for including recycled binder availability in mix design procedures to promote improvements in the cracking performance of mixtures by controlling the volumetric properties and the aggregate structure of the mix without having a detrimental effect on rutting resistance.

Performance Assessment of High Reclaimed Asphalt Pavement Asphalt Mixtures with Recycling Agents

The increased use of reclaimed asphalt pavement (RAP) in asphalt mixtures has promoted the use of recycling agents (RAs) to mitigate the effect of oxidized materials on the performance of asphalt mixtures. This laboratory-based study assesses the linear viscoelastic (LVE), cracking resistance, and permanent deformation properties of recycled asphalt mixtures containing RAs. The dosage levels used for this study were determined based on the manufacturer’s recommendation to restore the blended binder system’s low-temperature performance grade (PGL) to −22°C. The study found that blending a performance grade (PG) 64-22 virgin binder with RAs in high RAP mixtures can yield a comparable LVE response to high RAP mixtures designed using a softer binder (PG 58-28). Moreover, the study revealed that the cracking performance of high RAP mixtures could be improved without jeopardizing the rutting potential of the material by using RAs at dosage levels selected to yield a blended binder PGL of −22°C.

Investigation into the effect of waste engine oil and vegetable oil recycling agents on the performance of laboratory-aged bitumen

The pavement recycling method is one of the practical ways to integrate sustainable development into transportation infrastructure, and it has been adopted worldwide. The use of reclaimed asphalt pavement (RAP) in new asphalt highways is limited due to the ageing effects caused by UV damage and weathering on the asphalt binder. To address this issue, waste vegetable oil (WVO) and waste engine oil (WEO) have been proposed as potential rejuvenating agents to enhance the recyclability of pavements containing RAP. This study evaluated the effectiveness of WEO and WVO as chemical rejuvenating agents through various tests on both aged and virgin asphalt binders. The tests included measurements of ductility, fire, and flash points, softening points, and penetration. The results indicate that the addition of WEO and WVO can improve the low-temperature properties of asphalt binders when mixed with RAP, resulting in reduced stiffness. The mixture containing WEO and WVO exhibited improved stability compared to the control, suggesting enhanced flow with increasing waste oil content in comparison to aged binder, albeit with slightly reduced flow compared to the virgin binder. This study demonstrates the potential of WEO and WVO as recycling agents to enhance the performance of bituminous mixes incorporating RAP.

Use of Domestic Waste Polyethylene as a Bitumen Modifier in Bituminous Pavement Applications

The present study evaluated the use of domestic waste polyethylene (PE) in the applications of bituminous pavement. This study investigates the performance of the mixes using different waste PE percentages, i.e., 1%, 2%, 3%, 4% and 5%. It is observed that the softening point and elastic recovery value increase with PE content increases. The penetration index (PI) and temperature susceptibility of binders were evaluated. Adding PE to bitumen shows an improvement in the temperature susceptibility of the modified binders. The Marshall Stability value of bitumen containing 3% PE is higher at 69.65% than virgin binder stability. When 3% PE modified bitumen to the mixes, its indirect tensile strength (ITS) is 70.44 % higher than the conventional mix. The tensile strength ratio (TSR) value improved from 62% (unmodified binder) to 91.18% (modified binder) at 3% PE content, which is 47% higher than the conventional mixture. It indicates that the moisture susceptibility of mixes using PE is higher than conventional mix. Additionally, the mix deformation resistance with 3% PE was found to be 68.75% higher than the mix made with the unmodified binder. The study found that the bituminous mixes using PE have shown higher effectiveness in the properties such as stability, indirect tensile strength, rutting resistance, etc. of the mixes. It indicates that bituminous mixes with modified binders with PE provide higher resistance to permanent deformation.

Assessing the effects of copolymer modifier addition on asphalt attributes: Towards achieving performance optimization

The use of polymers to modify asphalt binders has become a widely accepted practice in modern pavement construction, offering a promising solution to address key factors contributing to asphalt pavement deficiencies. These factors include issues such as rutting, moisture-induced deterioration, and fatigue-related wear. The copolymer referred to as PGXpand was utilized as the modifying additive for the virgin binder in this study. It demonstrates exceptional performance in terms of high-temperature resilience and resistance to rutting. The impact of incorporating the PGXpand on asphalt properties was investigated. A comprehensive series of tests were conducted, covering storage stability, penetration, softening point, ductility, viscosity, and elastic recovery. Further analyses involved calculations of stiffness modulus, complex modulus, and phase angle. Mechanical and performance evaluations were also carried out, including Marshall properties, moisture susceptibility, creep compliance, and Kim tests. The results demonstrate the effectiveness of the PGXpand in enhancing asphalt performance, with modified mixtures exhibiting significant improvements compared to their unmodified counterparts. Consequently, integrating the PGXpand into asphalt technology emerges as a highly promising approach for optimizing road infrastructure, especially in regions with high-temperature conditions. Ultimately, such integration contributes substantially to the development of sustainable and resilient transportation networks.

Evaluation of the Mechanical Performance of Warm Bio-Recycled Asphalt Mixtures

Currently, approximately 90% of road pavement mixtures are derived from fossil fuels, a major source of the greenhouse gases contributing to global warming. This fact, together with the scarcity of raw materials in pavement engineering, has prompted recent investigations into sustainable alternatives. Biobinders, serving as substitutes or modifiers for petroleum-based asphalt binders, have gained attention, alongside the integration of recycled materials in recycled asphalt (RA). This study addresses these concerns by combining three techniques: (1) substituting a bitumen-based binder with a biobinder; (2) incorporating a high RA percentage (>30%); and (3) manufacturing the asphalt mixture at a reduced temperature (140 °C). These approaches result in the production and evaluation of warm bio-recycled asphalt mixtures. Materials were assessed at both the binder and mixture levels. The control binder, RA binder, and biobinder underwent conventional and rheological characterization. In terms of mixtures, warm bio-recycled asphalt mixtures employed a biobinder as the only virgin binder, with RA contents of 50% and 70%. Mechanical characterization focused on bearing capacity, cohesion, permanent deformations, and moisture damage. The warm bio-recycled asphalt mixtures exhibited adequate outcomes in bearing capacity through the stiffness modulus being 18,120 MPa and 15,683 MPa for bio-recycled asphalt with 50% RA and bio-recycled asphalt with 70% RA, respectively. Bio-recycled asphalt with 50% RA and bio-recycled asphalt with 70% RA showed low permanent deformation percentages, specifically 0.5% and 0.7%, respectively, in comparison to the reference recycled asphalt mixture with 1.5%, allaying concerns in practical applications due to the biobinder’s soft consistency. The bio-recycled asphalt mixture with 70% RA displayed good mechanical performance regarding the studied mechanical characterization, especially exhibiting the least susceptibility to water-induced damage with 97% of the retained indirect tensile strength ratio, addressing concerns related to moisture damage in warm asphalt mixtures with high RA content and biobinders. These findings offer valuable insights into the adoption of more sustainable practices in the asphalt pavement industry, reducing the concerns associated with warm bio-recycled asphalt mixtures.

Rejuvenating oxidized paving asphalts – When softeners meet asphaltene dispersants

The search and development of various asphalt rejuvenators have been following a trial-and-error methodology in essence; the imperative need of improved efficiency and versatility yearns for a general principle/framework of formulating rejuvenators. In this study, we propose one such formulation concept that rejuvenators can be designed by combining asphaltene dispersants (interacting with and dispersing asphaltenes) with softeners (diluting asphaltenes). This concept was preliminarily validated in an experimental program involving three rejuvenation schemes, namely using an aromatic softener alone (as the reference) and using it together with an ionic liquid or a phenolic compound (both acting as dispersants). Immediate and long-term rejuvenating effectiveness was evaluated based on viscoelastic properties, fatigue resistance, and moisture susceptibility. The results indicated that at respective optimum dosages, the three schemes all yielded satisfactory immediate performance of rejuvenation. After long-term aging, the rejuvenated asphalts demonstrated more desired viscoelastic characteristics in resisting high-temperature deformation and low-temperature cracking, and were more fatigue resistant, as compared to the virgin binder. Rejuvenation in all cases also recovered the moisture resistance nearly to the virgin level. Infrared spectrum analysis indicated that the performance restoration was accomplished by the agents blending physically with the aged binder, which decreased the concentrations of oxidation functional groups (carbonyl and sulfoxide). The incorporation of dispersants improved the aging resistance (in terms of high temperature viscoelasticity), and substantially reduced the need of aromatic softener while providing similar or better performance compared to using the softener alone, which would lead to pronounced environmental and economic benefits. The much higher dosage efficiency was ascribed to the capability of the dispersants in peptizing and dissociating the asphaltenes, as investigated by molecular dynamics simulations. The different dispersing behaviors of the additives were examined with reference to their chemical compositions and molecular structures.

Assessing recycled asphalt pavement: Impact of waste cooking oil and waste engine oil as rejuvenators on mechanical properties

Sustainable pavement construction is an extensively researched subject within the field of pavement engineering. Due to its environmental and commercial advantages, the construction of pavements utilizing recycled asphalt pavement (RAP) is progressively gaining popularity worldwide. Owing to the aging process, binder extracted from RAP is inherently harder than virgin binder and requires rejuvenation for application in high RAP blends. This paper investigates the performance characteristics of Waste Cooking Oil (WCO) and Waste Engine Oil (WEO) as rejuvenators in RAP-incorporated asphalt mixtures to assess their suitability for pavement use. The optimal rejuvenator content is determined based on the performance of physical properties. The study indicates that asphalt mixes rejuvenated with Waste Cooking Oil (WCO) demonstrate higher Marshall Stability values compared to mixes rejuvenated with Waste Engine Oil (WEO) at both 30% and 60% Recycled Asphalt Pavement (RAP) levels. Additionally, mixes incorporating WCO exhibit increased flow values. Furthermore, WCO outperforms WEO in Tensile Strength Ratio (TSR) at 30% RAP, with a slight decrease at 60% RAP. Results from Marshall and Indirect Tensile Strength (ITS) tests suggest that both WEO and WCO are effective rejuvenators, playing a critical role in aligning the properties of RAP-inclusive asphalt mixes with those of virgin mixes.