Conventional Asphalt Research Articles

Masterbatch Natural Rubber—Innovative Asphalt Cement Additive for Sustainable Flexural Pavements

The mechanical performance of Masterbatch Natural Rubber (MNR)-modified asphalt concrete (MNR-AC) was investigated and is presented in this paper. When compared to conventional asphalt concrete (AC), MNR-AC exhibits significantly superior performance across key mechanical parameters, including Marshall stability, indirect tensile strength (ITS), resilient modulus (IT Mr), indirect tensile fatigue life (ITFL), and rutting resistance. The most pronounced enhancements are observed at the optimal dry rubber to asphalt cement (r/b) ratio of 3%, at which MNR-AC demonstrates peak performance in all evaluated tests. The fatigue distress models for MNR-AC and AC reveal distinct logarithmic relationships, with an intersection point occurring at an r/b ratio of approximately 3%. This suggests that MNR-AC with an r/b ratio of 3% or less exhibits a markedly superior fatigue life compared to conventional AC under equivalent applied-stress conditions. MNR offers significant practical advantages over liquid natural rubber, including more consistent mixing, and simplified storage and transportation, positioning it as a promising and sustainable advancement in pavement material technology.

Plastic waste in dense asphalt mixes for road pavements

Recycling plastic waste in asphalt pavements records increasing statistic figures of application during the last decade worldwide. Due to environmental constraints, but also, to some beneficial properties of plastic waste, recycling in asphalt tends to become current practice, in several countries. In the Aristotle University of Thessaloniki (AUTH), the first attempt to produce asphalt mix using plastic waste consisted of mixing recycled plastic flakes with non-modified binder. Following an asphalt mix design in the laboratory, the whole mass of conventional aggregates was replaced by PET flakes. Recycled PET flakes were chosen to be introduced in the asphalt mix since they are hard, resilient and water repellent. Bitumen emulsion was first preferred as a binder to produce a cold asphalt mix. At a second stage of experimental research, plastic flakes replaced a part of the limestone sand while conventional asphalt 50/70 was used as a binder. At this stage, the experimental research provided more encouraging outcomes. Stability of asphalt mixes decreases as the plastics content in the mix increases, but all recorded values were still within limits of acceptance. At a third stage of research, LDPE recycled material of fine gradation was used to replace a part of the asphalt binder in dense mixes. The objective was to produce a modified binder and a more durable asphalt structure. Test results showed a significant improvement of the performance of asphalt mixes, in terms of strength and deformability of the asphalt mix structure. The research is completed by comparing the conventional techniques with the outcomes of the recycling process and by delineating potential fields of application of the recycled plastics in asphalt pavements.

Chemical and Rheological Evaluation of the Ageing Behaviour of High-Content Crumb Rubber Asphalt Binder.

High-Content Crumb Rubber Asphalt (HCRA) binder improves road performance and address waste tyre pollution, yet its ageing behaviour is not fully understood. In this study, 70# neat asphalt binder and HCRA with rubber contents of 35% and 50% were selected and aged through the Thin Film Oven Test (TFOT) and Pressure Ageing Vessel (PAV) tests. FTIR (Fourier Transform Infrared Spectroscopy) and DSR (Dynamic Shear Rheometer) were employed to investigate their chemical composition and rheological properties. The FTIR results show that HCRA's chemical test results are similar to those of 70#, but HCRA is more susceptible to ageing. I(C=C) strength decreases with age. The DSR results show that HCRA outperforms 70# neat asphalt binder in terms of viscoelasticity, high temperature performance and fatigue resistance, and exhibits greater resistance to ageing. The ageing index (AI) was obtained through a calculation using the formula, and overall, 70# neat asphalt binder is more sensitive to ageing behaviour and less resistant to ageing, and HCRA is particularly outstanding for fatigue resistance. A strong correlation is observed between chemical composition and some rheological property indicators. Therefore, we are able to predict the rheological properties using chemical composition indicators. This study provides insight into the ageing behaviour of a neat asphalt binder and an HCRA binder and demonstrates that the HCRA binder outperforms conventional asphalt in several performance areas. It also provides theoretical support for the consumption of waste tyres to prepare high content crumb rubber asphalt.

Evaluating and optimizing NBR-modified bituminous mixes: a rheological and RSM-based study.

Bitumen shows visco-elastic behavior, exhibiting both elastic and viscous properties as predicted by dynamic response and phase angle. Modern asphalt bituminous pavements face issues such as early-stage fatigue cracks, rutting, and permanent deformations due to low-temperature cracking, high-temperature deformation, moisture susceptibility, and overloading. These pavement distresses result in the formation of potholes, alligator cracks, and various deformations, which accelerate the need for rehabilitation and maintenance. To address these concerns, this study focused on utilizing Nitrile Butadiene Rubber derived from surgical gloves as an additive in conventional asphalt pavements to assess its effect on stiffness. Nitrile Butadiene Rubber was added in intervals of 2%, 4%, 6%, and 8% to conventional bituminous pavement. The rheological properties, marshall properties, dynamic modulus, and phase angle were evaluated for varying percentages of Nitrile Butadiene Rubber at different temperature, and frequency. The dynamic response was determined using a simple performance tester at four different temperatures (4.4°C, 21.1°C, 37.8°C, and 54.4°C) and six different frequencies (0.1, 0.5, 1, 5, 10, and 25Hz). Response surface methodology was employed to establish a relationship between input and output variables and to optimize the amount of Nitrile Butadiene Rubber in the mix based on dynamic modulus and phase angle. The study concluded that adding up to 6% of Nitrile Butadiene Rubber improved Marshall stability, while higher percentages led to reduced stability. A similar trend was observed in the dynamic modulus, which peaked with the addition of 6% Nitrile Butadiene Rubber, regardless of frequency and temperature. The response surface methodology model indicated that coupling the percentage of Nitrile Butadiene Rubber with frequency increased the dynamic modulus at a constant temperature, with the highest value occurring at 4.4°C. However, the dynamic modulus decreased as the temperature rose for the same combinations of Nitrile Butadiene Rubber percentages and frequencies. Numerical optimization suggested that a maximum of 5.9% Nitrile Butadiene Rubber should be added to achieve the highest dynamic modulus and lowest phase angle.

Asphalt pavement structural competency during staged airfield runway construction strategy

ABSTRACT This paper reports the results from a full-scale evaluation of asphalt pavement structural competency during a multi-stage construction strategy. The staged pavement construction included three stages: (1) new conventional asphalt pavement, (2) unpaved full depth reclaimed (FDR) pavement, and (3) thin surface asphalt paved FDR layer. The full-scale pavement sections consisted of a standard and substandard pavement structural design. The accelerated pavement testing (APT) experiments were executed by simulating the loading conditions of an aircraft with a critical combination of relatively high wheel load and high tire inflation pressure. The structural capacity of the pavement test items was monitored using a falling weight deflectometer. From this study, the staged pavement construction concept was found to be a potential approach to extend the service life of asphalt pavements. Unpaved FDR layers are structurally competent to support a low volume of aircraft operations. These findings support the transition to the use of asphalt pavements containing an FDR layer from an experimental to routine rehabilitation practice for airfield asphalt pavements.

Innovative Pavement Solutions: A Comprehensive Review from Conventional Asphalt to Sustainable Colored Alternatives

Climate change significantly impacts transportation infrastructure, particularly asphalt pavements. Similarly, the heat absorption of paved surfaces, especially conventional black pavements, significantly intensifies the urban microclimate. Paved surfaces, including asphalt pavements, account for over 30% of the covered surfaces and are vulnerable to rising temperatures, which cause not only pavement distress, such as rutting and cracking, but also urban heat islands (UHI). Sustainable pavement solutions, specifically colored pavements, have been investigated for their potential to mitigate these effects. This review presents an extensive overview of current pavement technologies, emphasizing conventional asphalt’s economic, environmental, and functional characteristics. A discussion of the benefits and challenges of colored pavements is also provided, including their ability to reduce UHI, enhance safety, and contribute to sustainable urban growth. This paper discusses advancements in pavement material science, the use of recycled materials, and the application of reflective coatings, providing insights into sustainable infrastructure development. Transitioning from conventional black pavements to sustainable colored alternatives is not merely a matter of material choice but a strategic transition toward resilient urban planning. Increasing demand for environmentally friendly infrastructure could prompt the construction industry to adopt colored pavements as a tool to promote environmental stewardship.

Tyre/road noise frequency spectra analyses based on CPX measurement with six microphones

Road traffic noise is affected by many factors, the road surface being one of them. The CPX method (ISO 11819-2) is the method used to measure tyre/road noise, i.e. noise generated by tyre-surface contact. Up to six microphones are positioned around reference tyre (ISO 11819-3) in specified positions as the standard requires. Two microphones are mandatory; four are optional. Conventional stone mastic asphalt, low-noise pavement, exposed aggregate cement concrete and cobblestones were measured by the CPX method using six microphones at a velocity of 80 km/h. Tyre/road noise frequency spectra from each microphone will be shown in this paper. Presented results should be used to discussion about positions or necessity of mandatory and optional microphones.

Noise-reducing double-layer porous pavement with steel slag as aggregate in the top layer

This paper presents results of a trial replacing the natural aggregate in the top layer of a double-layer porous asphalt pavement with steel slag. A 200 m long motorway section was paved with this material and performance in terms of macrotexture and noise properties (made annually with the CPX method) were monitored for an entire life-cycle of 7 years. The results in terms of noise reduction compared to the common Swedish reference pavement (SMA16) indicated an initial noise reduction of about 7 dB; only marginally lower than the same pavement with normal natural aggregate. By time, this marginal loss in noise reduction was turned into a somewhat higher noise reduction after 5-6 years of service. This was surprising since the steel slag pavement appeared to clog a little more than the conventional double-layer asphalt pavement. Probably, there are (uncertain) properties in the slag material which balances out the clogging effect. At the present time this pavement has reached an age of 7 years, which is similar as the conventional porous pavement has served on the same road over two lifecycles so far. With its lower noise-reducing deterioration versus time, steel slag is a promising material for recycling in this way.

Acoustic road surface maintenance on low noise asphalts in Switzerland with grinding

This study investigates the effectiveness of grinding techniques on special low-noise pavements as well as conventional asphalt surfaces in order to restore or enhance their noise-reducing properties. This study analyzes 17 different test tracks where grinding techniques were applied, featuring various surface types and stages of aging. The research employs Close-Proximity-Measurements (CPX) and additional methods to evaluate surface characteristics. Initial results reveal significant acoustic improvements from grinding, especially on surfaces with 4- and 8-mm maximum aggregate size. However, the durability of these measures varies, with 4~mm surfaces returning to baseline after 2-4 years, while 8 mm surfaces benefit for approximately 4 years. The study demonstrates that grinding methods can enhance acoustics through surface texture improvement and partially reactivating previously clogged pore spaces. The effectiveness depends on the initial acoustic state and grinding depth, emphasizing the importance of setting clear objectives for optimal results. In summary, this study underscores the effectiveness of grinding in enhancing the acoustic quality of low-noise road surfaces. Moreover, its integration into road surface maintenance strategies is a new tool for extending the functional and acoustic lifespan of low-noise road surfaces.

Evaluating the Environmental Impact of Reusing Baghouse Dust in Asphalt Concrete: A Sustainable Approach

The purpose of this study is to assess the environmental impact of reusing baghouse dust in asphalt concrete production. Baghouse dust, a byproduct of asphalt creation, presents natural removal challenges; nonetheless, its true capacity reuse in asphalt concrete could give an economical solution. This study aims to survey and align the environmental and ecological implications of utilizing varying extents of baghouse dust in asphalt mix combinations. This research review starts by describing the physical and chemical properties of baghouse dust. In this way, substantial samples were ready and prepared with various percentage rates of baghouse residue to examine the effect on the mechanical properties of the mix. The discoveries demonstrate that consolidating baghouse dust into asphalt cement mostly decreases peak stress and strength qualities characteristics. As far as the environmental and ecological effect, the investigation analysis shows that utilizing baghouse residue can decrease in general energy utilization and discharge emissions. The energy utilization rate diminished from 500 MJ/ton for ordinary conventional asphalt to 400 MJ/ton for asphalt with 20% baghouse residue, and CO2 emanations decreased from 120 kg/ton to 80 kg/ton for a similar correlation. Also, the squander and waste decrease was huge, with 200 tons/year saved at 10% baghouse dust and 400 tons/year at 20%. Asset resources proficiency likewise improved, with raw unrefined material savings investment funds of 150 tons/year at 10% baghouse dust and 300 tons/year at 20%. Notwithstanding this decrease, the mechanical properties stay within ranges for specific applications, proposing that baghouse dust residue can be effectively and successfully utilized in non-basic underlying structural layers of asphalts.

Moisture Sensitivity Performance of Hot Mix Asphalt Mixture Incorporating Fly Ash Geopolymer (FAG) Asphalt Binder

In Malaysia, Hot Mix Asphalt (HMA) is widely used in asphalt production. HMA is a mixture of asphalt and aggregates that give durability to the road surface for pavement. Due to vehicles excessive traffic loadings that cause road surface damage, this pavement technology frequently undergoes maintenance and rehabilitation work. This study used recycled material as a modified binder and showned the best result in increasing stiffness and better rutting performance with high percentages of additives. This research focuses on the effect of FAG additive on asphalt mixture performance evaluation according to SuperpaveTM mixes design method. The procedures were specified according to the American Association of State Highway and Transportation Officials (AASHTO), American Society for Testing and Materials (ASTM), British Standard (BS) and Malaysian Standard (MS). The granite aggregate type was produced by a local quarry with conventional asphalt binder grade 80/100 and 60/70. Incorporation FAG in modified asphalt binder as levels of 0, 3, 5, 7, 9, and 11% by mass of asphalt binder. The performance of moisture sensitivity showed low moisture damage susceptibility for the mixture based on consistent values of TSR, in which all the specimens met the minimum TSR threshold of 80%. The optimization findings indicated that 9% of fly ash geopolymer might be the ideal content for modifying the asphalt binder. Overall, research findings suggest that using geopolymers may have improved some of the characteristics of asphalt binder and the performance of asphalt binders in pavement applications. Thus, the outcomes of this research were significantly used for further performance test and analysis on the asphalt mixture.

The Production of Porous Asphalt Mixtures with Damping Noise Reduction and Self-Healing Properties through the Addition of Rubber Granules and Steel Wool Fibers.

Conventional asphalt roads are noisy. Currently, there are two main types of mainstream noise-reducing pavements: pore acoustic absorption and damping noise reduction. However, a single noise reduction method has limited noise reduction capability, and porous noise-reducing pavements have a shorter service life. Therefore, this paper aimed to improve the noise-damping performance of porous asphalt mixture by adding rubber granules and extending its service life using electromagnetic induction heating self-healing technology. Porosity and permeability coefficient test, Cantabro test, immersion Marshall stability test, freeze-thaw splitting test, a low-temperature three-point bending experiment, and Hamburg wheel-tracking test were conducted to investigate the pavement performance and water permeability coefficients of the mixtures. A tire drop test and the standing-wave tube method were conducted to explore their noise reduction performance. Induction heating installation was carried out to study the heating rate and healing performance. The results indicated that the road performance of the porous asphalt mixture tends to reduce with an increasing dosage of rubber granules. The road performance is not up to the required standard when the dosage of rubber granules reaches 3%. The mixture's performance of damping and noise tends to increase with the increase of rubber granule dosage. Asphalt mixtures with different rubber granule dosages have different noise absorption properties, and the mixture with 2% rubber granules has the best overall performance (a vibration attenuation coefficient of 7.752 and an average absorption factor of 0.457). The optimum healing temperature of the porous asphalt mixture containing rubber granules and steel wool fibers is 120 °C and the healing rate is 74.8% at a 2% rubber granule dosage. This paper provides valuable insights for improving the noise reduction performance and service life of porous asphalt pavements while meeting road performance standards.

Predicting the Influence of Pulverized Oil Palm Clinker as a Sustainable Modifier on Bituminous Concrete Fatigue Life: Advancing Sustainable Development Goals through Statistical and Predictive Analysis

Currently, the viscoelastic properties of conventional asphalt cement need to be improved to meet the increasing demands caused by larger traffic loads, increased stress, and changing environmental conditions. Thus, using modifiers is suggested. Furthermore, the Sustainable Development Goals (SDGs) promote using waste materials and new technologies in asphalt pavement technology. The present study aims to fill this gap by investigating the use of pulverized oil palm industry clinker (POPIC) as an asphalt–cement modifier to improve the fatigue life of bituminous concrete using an innovative prediction approach. Thus, this study proposes an approach that integrates statistically based machine learning approaches and investigates the effects of applied stress and temperature on the fatigue life of POPIC-modified bituminous concrete. POPIC-modified bituminous concrete (POPIC-MBC) is produced from a standard Marshall mix. The interactions between POPIC concentration, stress, and temperature were optimized using response surface methodology (RSM), resulting in 7.5% POPIC, 11.7 °C, and 0.2 MPa as the optimum parameters for fatigue life. To improve the prediction accuracy and robustness of the results, RSM and ANN models were used and analyzed using MATLAB and JMP Pro, respectively. The performance of the developed model was assessed using the coefficient of determination (R2), root mean square error (RMSE), and mean relative error (MRE). The study found that using RSM, MATLAB, and JMP Pro resulted in a comprehensive analysis. MATLAB achieved an R² value of 0.9844, RMSE of 3.094, and MRE of 312.427, and JMP Pro achieved an R² value of 0.998, RMSE of 1.245, and MRE of 126.243, demonstrating higher prediction accuracy and superior performance than RSM, which had an R² value of 0.979, RMSE of 3.757, and MRE of 357.846. Further validation with parity, Taylor, and violin plots demonstrates that both models have good prediction accuracy, with the JMP Pro ANN model outperforming in terms of accuracy and alignment. This demonstrates the machine learning approach’s efficiency in analyzing the fatigue life of POPIC-MBC, revealing it to be a useful tool for future research and practical applications. Furthermore, the study reveals that the innovative approach adopted and POPIC modifier, obtained from biomass waste, meets zero-waste and circular bioeconomy goals, contributing to the UN’s SDGs 9, 11, 12, and 13.

Characteristics of the Warm Mix Asphalt with Emulsion as Additives in Engineering

The technology known as Warm Mix Asphalt (WMA), just unveiled in Europe, is becoming increasingly popular across the globe. By lowering the bitumen binder's viscosity, this cuttingedge technique makes asphalt mixtures more workable at lower temperatures between 30-40°C needed to generate conventional Hot Mix Asphalt (HMA). Reduced pollutants, energy savings, and a less offensive smell result from the lower mixing and compaction temperatures. More studies are necessary to evaluate its long-term performance. Based on MORTH requirements, this study examines the efficacy of bitumen emulsion as an addition in WMA samples of Stone Matrix Asphalt (SMA) and Dense Bituminous Macadam (DBM) mixtures. The combinations' binder contents varied from 4% to 7% of the aggregate weight. For the DBM and SMA mixes, cement and stone dust were utilized as fillers, and VG 30-grade bitumen was employed as the binder. For SMA and DBM mixtures, the ideal binder contents were determined to be 6.92% and 6.32%, respectively.

Evaluation of the properties of bio-asphalt derived from waste cooking oil and low-density polyethylene through the pyrolysis process

The aim of this study is to prepare a bio-asphalt for flexible pavement construction using a fixed-bed pyrolysis reactor. This method involves incorporating waste cooking oil (WCO) and low-density polyethylene (LDPE) as feedstock materials. Through this study, an attempt has been made to make use of waste materials and promote the use of environmentally friendly binders in sustainable road construction. The pyrolysis experiment was conducted at different temperatures, varying from 250 °C to 500 °C for different blends of waste cooking oil (WCO) and low-density polyethylene (LDPE), i.e., 1:0, 3:1, 1:1, 1:3, and 0:1, respectively. At a temperature of 350 °C, the pyrolysis process is more effective for converting various blends of waste cooking oil (WCO) and low-density polyethylene (LDPE) into bio-asphalt. The maximum bio-asphalt yield of 82 wt% was reported for the 1:3 blend at a temperature of 350 °C. The elemental analysis of an equal mass of waste cooking oil (WCO) and low-density polyethylene (LDPE) reported a carbon content of 83.93 wt%, a hydrogen content of 13.29 wt%, and a lower oxygen content of 2.55 wt%. The Gas Chromatography Mass Spectrography (GC-MS) analysis indicated the presence of chemical compounds such as pentadecane, heptadecane, dodecane, cyclopentylpropyl, and hexacosene in the 1:1 blend. The thermogravimetric and derivative thermogravimetric analyses indicate that the 1:1 blend and 1:3 blend can withstand temperatures around 473 °C and 475 °C, respectively. The Fourier transform infrared spectroscopy (FT-IR) analysis showed the presence of alkane, alkene, ester, and other aromatic compounds. Based on this present study, it has been noted that the chemical composition of a 1:1 blend of waste cooking oil (WCO) and low-density polyethylene (LDPE)-based bio-asphalt contains similar chemical compositions as asphalt binder, and it can be used as a modifier for conventional asphalt binder.

Laboratory evaluation of synergistic blending with SBS-modified bitumen and rejuvenator to enhance the performance of recycled bitumen with a high content of RAP materials

Reclaimed asphalt pavement (RAP) stands as a pivotal construction material widely used in asphalt pavement rehabilitation. The prevailing focus and trajectory revolve around increasing the proportion and utility of RAP materials. However, the potential for temperature and fatigue cracking increases with the dosage of RAP materials. In this study, SBS modified bitumen (SBSMB) and four rejuvenators were combined synergistically with aged asphalt to enhance the performances of the recycled bitumen with high RAP content and consequently augment the value of the RAP material, all while ensuring compatibility between the SBSMB and aged base bitumen. Initially, the base bitumen was aged using a pressure aging vessel (PAV) test. Subsequently, a selection of virgin bitumen (VB), SBSMB, and four rejuvenators were utilized to revitalize the aged bitumen. A comprehensive battery of tests, encompassing conventional tests, temperature sweep, frequency sweep, multiple stress creep recovery (MSCR), bending beam rheometer (BBR), and linear amplitude sweep (LAS), were carried out to characterize the rheological properties. Finally, Fourier transform infrared spectroscopy (FTIR) was employed, along with the determination of polystyrene index (IPS) and polybutadiene index (IPB), to evaluate the compatibility between SBSMB and aged base bitumen. The results underscore that the incorporation of SBSMB and rejuvenator comprehensively enhances high-temperature performance and fatigue cracking resistance while effectively reinstating low-temperature cracking resistance. Furthermore, the values of IPS, IPB, and IPS/IPB exhibit an increase with the addition of a rejuvenator, indicating its potential to improve the compatibility between SBSMB and aged base bitumen. Thus, this research proposes a more cost-effective and environmentally sustainable approach to bolstering conventional asphalt pavement performance and grade.

Experimental investigation on fatigue and fracture behaviour of cold recycling materials

Cold Recycled Material (CRM) has emerged as a highly innovative road construction material, offering numerous advantages over conventional Hot Mix Asphalt (HMA), such as reduced construction costs, decreased energy consumption, and enhanced resistance to reflective cracking. CRM is primarily composed of Reclaimed Asphalt (RA) and bitumen emulsion, with the addition of cement as a co-binder. However, the presence of cement in CRM can lead to increased susceptibility to cracking under heavy traffic loads. In this study, the fracture-fatigue behaviour of CRM modified with by-product fillers was investigated in order to improve the overall performance of CRM mixtures. The Cyclic Indirect Tensile Fatigue test (CIT-CY) and Semi-Circular Bending (SCB) fracture tests were conducted on the CRM mixtures and mortars, respectively. The findings reveal that CRM materials incorporating specific fillers demonstrated a balanced combination of fatigue and fracture resistance, indicating the potential for these modified CRMs to enhance road construction applications.

Introducing Diels‐Alder reaction with carbon nanotubes for the enhanced repair performance of epoxy resin modified asphalt

AbstractEpoxy asphalt, a thermosetting polymer, is characterized by stable, irreversible internal chemical bonds that prevent recovery and spontaneous micro‐crack healing, unlike conventional asphalt. This study introduces a renewable nano‐modifier synthesized via esterification of carboxyl‐functionalized carbon nanotubes (CNTs‐COOH) and furfuryl alcohol (FA), termed CNTs‐FA. The successful synthesis of CNTs‐FA was confirmed through various microscopic techniques. Integrating CNTs‐FA into epoxy asphalt materials, the optimal dosage was identified as 0.05% of the total epoxy asphalt mass using tensile tests and fluorescence microscopy. Thermal reversible effects and mechanisms were further analyzed through multiple regeneration cycles using tensile properties, fluorescence microscopy, and infrared spectroscopy. The study elucidates that the thermal reversibility in epoxy asphalt is facilitated by the Diels‐Alder (DA) reaction between the conjugated diene structure in FA and the curing agent oleylamine. This research provides an effective solution to the non‐recoverability and unrepairable micro‐cracks of traditional epoxy asphalt mixtures.Highlights CNTs‐FA was successfully prepared by esterification reaction. Using nano modification methods, introduce DA reaction into curing system. Renewable function of epoxy asphalt by DA reversible reaction.

Enhancement of porous asphalt mixtures modified with various fibers and ethylene–vinyl acetate polymer

Porous asphalt mixture is conventional hot mix asphalt (HMA) with substantially decreased fines, which produces an open-graded mixture that enables the water to flow through an interconnected void space. Porous asphalt is a permeable system that has a lot of benefits. However, because of its open structure, the durability of this mixture decreases, and both its stability and resilient modulus are much lower compared to the dense conventional asphalt mixtures. Also, the high void percentage may lead to an increase in the draindown proportion. Fibers (cellulose or mineral) and polymer-modified binders are recommended for porous asphalt mixtures, especially in hot and moderate climates. The objective of this study is to improve the porous asphalt mixture's performance by using ethylene–vinyl acetate (EVA) polymer-modified bitumen. Two types of fibers (cellulose fibers and glass wool fibers) were used, separately to determine the control mixture. Four different proportions of EVA polymer were added to the bitumen (1%, 2%, 3%, and 4%) and Scanning Electron Microscopy (SEM) was used for better investigating of the bitumen microstructure, then The Marshall mix design was used to determine the optimum EVA content (OEC) for the porous asphalt mixture. Several performance tests were conducted to investigate the characteristics of the porous asphalt mixture, such as the infiltration rate, binder draindown, the wheel track and the cantabro abrasion tests. The findings of the study conclude that the addition of EVA polymer to the porous asphalt mixtures enhances the performance as it increases stability by 20.8% and the infiltration rate by 20.6%. It decreases binder draindown proportion by 33.3%, cantabro abrasion loss by 25.1% and the rut depth at 5,000 cycles and 10,000 cycles by 29.8% and 19.7%, respectively.

Recyclability potential of waste plastic-modified asphalt concrete with consideration to its environmental impact

The use of waste plastic into asphalt concrete paving mix (ACP) has been explored in recent literature to improve the functional properties of the mix. However, exploration on their recyclability potential at the end of its service life remains scarce. This study explores the potential of recycling aged waste plastic-modified asphalt concrete (AACP) for road pavements, with focus on four commonly disposed household plastics: high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS) and polyethylene (PET). Marshall stability test, Cantabro abrasion test, indirect tensile strength test, resilient modulus (MR) test, Hamburg’s wheel tracking test and stripping test were performed to evaluate the engineering properties of recycled waste plastic-modified asphalt concrete (RACP) containing proportions ranging from 20 % to 100 % aged component (AACP) blended with virgin mixtures. This paper highlights significant engineering performance of RACP, and most notably for RACP containing PP with 20 % aged content which exhibits 1.6 times greater resistance to moisture damage compared to conventional recycled asphalt concrete (RAPA). Although RACP with HDPE and PP (consisting of 20 % and 40 % AACP in mix) yield improvements in resilient modulus over RAPA, this improvement is less pronounced for RACP with PS and PET. Overall, RACP with 40 % aged components exhibits better rutting, moisture damage and abrasion loss performance, along with improved stability and flow value. Environmental impact in terms of water leachability was also found to be negligible in this study and RACP can be considered a feasible sustainable pavement material, with potential for second and more lives.