Production Of Asphalt Mixtures Research Articles

Assessment of the effectiveness of binder fatigue, rheology and chemistry parameters in evaluating cracking resistance in high RAP mixtures modified with recycling agents

The utilization of Reclaimed Asphalt Pavement (RAP) in pavement construction has gained prominence as a sustainable approach to reduce material costs and environmental effect. However, a significant challenge associated with increased RAP incorporation lies in the potential fracture distress caused by the aged binder. The purpose of this study is to assess the cracking performance of asphalt mixtures incorporating three levels of recycled materials (30% RAP, 50% RAP, and 30% RAP along with 5% Reclaimed Asphalt Shingles (RAS)). Three softening oils were employed to improve the cracking performances at two aging levels. Performance evaluations, including cracking performance assessments at intermediate and low temperatures, were carried out and compared with control mixtures. The findings of this study reveal that the incorporation of softening oils, as investigated herein, offers a viable means of producing asphalt mixtures featuring high RAP content while preserving performance comparable to that of a virgin mix. From a binder perspective, the Glover–Rowe (G–R) parameter and fatigue life at 10% strain level emerge as robust indicators for evaluating cracking resistance under conditions pertaining to intermediate and low temperatures.

ОПТИМІЗАЦІЯ ТЕМПЕРАТУРИ ПРИГОТУВАННЯ, ВМІСТУ ЕНЕРГОЗБЕРІГАЮЧОЇ ДОБАВКИ ТА АСФАЛЬТОБЕТОННОЇ КРИХТИ ПІД ЧАС ВИГОТОВЛЕННЯ ТЕПЛИХ АСФАЛЬТОБЕТОННИХ СУМІШЕЙ

Introduction. The article investigates the effect of the preparation temperature, the amount of energy-saving additive and the amount of asphalt crumb on the physical and mechanical properties of warm asphalt mixtures. The method of experimental and statistical modeling was used in the study, and mathematical models describing the dependence of water saturation and compressive strength of asphalt concrete were developed. Based on the analysis of the results obtained, the areas of optimal values of the preparation temperature, the amount of energy-saving additive, and the amount of asphalt crumb during the production of warm asphalt mixtures were determined. In this case, the resulting mixture meets the standard requirements for hot fine-grained asphalt mixtures in terms of physical and mechanical properties. Problem statement. Studies by the authors of [1] have shown that when preparing an asphalt mixture, it is very important to take into account changes in the properties of bitumen, which is the main component that characterizes the behavior of asphalt concrete. In the preparation of warm asphalt mixtures, it is advisable to use energy-saving additives, the introduction of which provides relatively new chemical effects that improve the workability, mobility and energy saving of mixtures made at lower temperatures than traditional hot mixtures. At the same time, due to the large number of different types of additives, there is no accurate quantitative data on the dependence of asphalt concrete properties on the content of additives at different amounts of bitumen for different types of asphalt mixtures.

ДОСВІД ВИКОРИСТАННЯ ЗОЛИ ВИНЕСЕННЯ В ЯКОСТІ НАПОВНЮВАЧІВ В АСФАЛЬТОБЕТОНІ

Introduction. Fly ash is a by-product of electricity generation using coal or other solid fuels. It is a material containing various chemical compounds such as calcium, potassium and sodium oxides. Since fly ash is not a biodegradable material and can have a negative impact on the environment, its use in asphalt concrete is one of the possible ways to reduce waste and improve the environmental situation, as well as reduce the use of natural resources. Problem statement. Road construction with asphalt pavements requires a large number of components of these mixtures. In this regard, the need for scarce carbonate mineral filler is growing. Therefore, it is advisable to consider research aimed at studying industrial by-products, in particular fly ash, in order to use them as mineral fillers for asphalt concrete. Objective. To analyze the existing experience of using fly ash as a mineral filler in the production of asphalt mixtures for further implementation and improvement of environmental safety and performance characteristics of road pavements due to new road construction materials. Materials and methods. Analysis of information sources and experience in the use of industrial waste as mineral filler, study of requirements for materials and their composition.

Organic expanded vermiculite as an alternative to filler for improving aging resistance of asphalt mixture

The organic expanded vermiculite (OEVMT) is a good anti-aging agent for asphalt binder due to its excellent heat and oxygen barrier properties. However, the application form of OEVMT is usually limited to being as a modifier for asphalt binder while seldom research takes it as an alternative to filler in asphalt mixture. Using the OEVMT as an alternative to filler has the potential to further improve the aging resistance of asphalt mixture in comparison with using the OEVMT as an asphalt binder modifier, because the amount of OEVMT in asphalt mixture can be largely increased in this case. In present study, different proportions of fillers in asphalt mixture were replaced by OEVMT to produce asphalt mixtures with better aging resistance. The effects of using OEVMT as an alternative to fillers on road performance and aging resistance of asphalt mixture were investigated. The results indicate that replacing a large proportion of fillers in asphalt mixture can lead to a poor moisture resistance of asphalt mixture. In comprehensive consideration of moisture, cracking and rutting resistances, the optimal proportion of filler that should be replaced by OEVMT is 12.5 %. In comparison with the form of using OEVMT as a modifier for asphalt binder, using an appropriate amount of OEVMT to replace limestone fillers in asphalt mixture can further enhance the aging resistance of asphalt mixture by increasing the amount of OEVMT in asphalt mixture.

Recycling waste plastics in asphalt mixture: Engineering performance and environmental assessment

The surging quest for asphalt pavement sustainable approaches promotes the need for balancing environmental and economic benefits. With the global production of waste plastics (WP) reaching drastic levels and recycling rates remaining disappointingly low, policymakers are increasingly advocating for the reuse of post-consumer recycled plastics in construction materials. In this study, recycling WP emerges as the most feasible solution, particularly when considering the environmental hazards associated with burning and landfilling, such as air and soil pollution. Recycling WP in asphalt mixture specifically has been quested due to the high-daily production of asphalt mixture, but concerns exist regarding its engineering performance. This study's focus is to assess the asphalt mixture mechanical response while incorporating WP, particularly High-Density Polyethylene (HP), in addition to assessing their environmental impacts. Four asphalt mixtures were rigorously evaluated containing four different asphalt binders: polymer-modified PG 76–22 and PG 70–22, unmodified PG 67–22, and HP-modified PG 67–22 asphalt binders. The investigation encompassed an in-depth analysis of asphalt binder rheological characteristics and asphalt mixtures' mechanical properties. A pivotal aspect of this study was comparing the environmental benefits of HP-modified asphalt binders against conventional polymer-modified ones. This comparison was conducted through a detailed cradle-to-gate life-cycle assessment (LCA). Results indicate that asphalt mixture containing WP material demonstrated similar engineering performance as compared to conventional mixture containing PG 70–22 asphalt binder. Further, the LCA analysis revealed that the inclusion of HP WP in asphalt binders, as compared to PG 76–22 and PG 70–22 asphalt binders, can significantly lower the global warming potential by 17.7% and 8.9%, respectively.

Production of an Eco-friendly Stone Matrix Asphalt Mixture Using Recycled Additives

Production of an Eco-friendly Stone Matrix Asphalt Mixture Using Recycled Additives

Comprehensive evaluation of energy consumption and carbon emissions of asphalt pavement recycling technology

To assess the energy saving and emission reduction effects of recycling technology, the quantitative analysis of energy consumption and carbon emission of recycled asphalt pavement is conducted of asphalt mixture production, transportation, paving and compaction. Firstly, the calculation model for energy consumption and carbon emissions of recycled asphalt pavement is established during the construction stage. In addition, the energy consumption and carbon emission of four recycling technologies, including the HCPR, HIR, CCPR and CIR, were compared. Finally, the FCE method is used to evaluate the actual effect of energy saving and emission reduction from the perspectives of the ecological benefit and the economic benefit. The research results indicate the most serious stage of energy consumption is the new material production stage, and the most serious stage of carbon emission is the asphalt mixture production stage of recycled asphalt pavement. Taking the HCPR technology as an example are calculated in detail. The energy consumption of the HCPR technology in the four stages of the construction stage was 17.59 MJ, 344.45 MJ, 228.51 MJ and 25.85 MJ, respectively, and the emissions in the four stages of the construction stage were 1307.89 g, 5971.28 g, 19,251.24 g and 1949.82 g, respectively. For different recycling technologies in the construction stage, the energy-saving ratios of HCPR, HIR and CCPR are 13.62%, 9.61% and 19.24% respectively when compared with the typical scheme, which have a certain energy-saving effect. However, the energy consumption of CIR reduced by 43.63%, which the energy saving effect is most significant. Moreover, the emission reduction ratios of HCPR, HIR and CCPR are 2.3%, 9.23% and 1.01% respectively when compared with the typical scheme, the emission of CIR reduced by 30.76%, so the emission reduction effect of CIR is most significant. Furthermore, the comprehensive evaluation score of the CIR technology with the most significant energy saving and emission reduction effect is 0.8021 in terms of ' ecological benefits ' and 0.8074 in terms of ' economic benefits '. In summary, it is recommended to adopt CIR technology in the engineering project, which can achieve the most significant energy-saving and emission reduction effects.

Effect of asphalt modified with waste engine oil on the durability properties of hot asphalt mixtures with reclaimed asphalt pavement

Abstract The increased demand for asphalt and other materials involved in the construction of pavement led to an increase in the cost of these materials, which calls for searching for alternatives to virgin materials that can be used to produce asphalt mixtures. Reclaimed asphalt pavement (RAP) was employed in this study and regenerated using oxidized asphalt modified with waste engine oil (WEO). This method can achieve economic and environmental benefits. After improving the properties of oxidized asphalt using WEO, it was used with reclaimed asphalt mixtures (RAP). When the RAP was added at ratios of 20, 30, 40, and 50%, an improvement can be noticed in the mechanical performance of the asphalt mixtures renewed with oxidized asphalt and WEO and an increase in its resistance to stripping. When reclaimed asphalt pavement (RAP) is added to hot mix asphalt (HMA) at concentrations of 20, 30, 40, and 50%, respectively, the Marshall stability of HMA is improved by 10, 20, 28, and 9.5%, the flow is declined by 1% for all ratios of RAP except for 50% RAP where the flow decline by 3%, the unit weight is enhanced, the quantity of air voids in the mix is preserved within allowable ranges, and the resistance to stripping is increased by 62, 77, 85, and 76%, respectively. Research also shows that incorporating 40% RAP enhances the resistance to moisture by about 5.9%. The addition of 40% RAP reduced the Cantabro loss values by about 2 and 16% for both aging and non-aging samples, respectively. The rutting resistance increased by 50 and 47% for mixes with 40% RAP at 50 and 60°C, respectively. As a result, it became evident that mixtures containing RAP material could be effectively adapted to satisfy the relevant volumetric and performance requirements.

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.

Quantifying the agglomeration effect of reclaimed asphalt pavement on performance of recycled hot mix asphalt

The utilization of reclaimed asphalt pavement (RAP) is becoming widespread in asphalt pavement industry. However, the agglomeration of RAP might exist during asphalt mixture production, which can affect the performance of asphalt mixtures. This study aimed to develop an innovative RAP agglomeration quantification method and investigate the agglomeration effect on performance of recycled hot mix asphalt (RHMA). The inherent agglomeration rate (IAR) and relative agglomeration rate (RAR) were defined and quantified by using the gradation curves. The RAP agglomeration was further determined under different mixing conditions including aggregate size, mixing time, temperature, etc. The influence of RAP agglomeration on hot mix asphalt mixture (HMA) was characterized through wheel rutting, low-temperature cracking, and moisture resistance testing. Results showed that RAP agglomeration do exist during asphalt mixture production, especially for high RAP content. The gradation curves from screening test proved to be an effective approach for RAP agglomeration quantification. The agglomeration rates of No.1, No.2, and No.3 RAP aggregates could be reduced by 5.7, 6.5 and 39.8 % under appropriate mixing conditions. But the fine RAP aggregates were easily re-agglomerated to form the coarse RAP aggregates. The ratio of 150 % between virgin coarse aggregate and RAP aggregate could avoid re-agglomeration issue for No.2 and No.3 RAP aggregates. Based on the rutting, low-temperature cracking, and moisture resistance tests, the impact of agglomeration phenomenon on the performance of plant RHMA with containing 100 % RAP was more than that with containing 50 % RAP.

Assessment of Traditional Asphalt Mixture Performance Using Natural Asphalt from Sulfur Springs

This research utilized natural asphalt (NA) deposits from sulfur springs in western Iraq. Laboratory tests were conducted to evaluate the performance of an asphalt mixture incorporating NA and verify its suitability for local pavement applications. To achieve this, a combination of two types of NA, namely soft SNA and hard HNA, was blended to create a binder known as Type HSNA. The resulting HSNA exhibited a penetration grade that adhered to Iraqi specifications. Various percentages of NA (20%, 40%, 60%, and 80%) were added to petroleum asphalt. The findings revealed enhanced physical properties of HSNA, which also satisfied the requirements outlined in the Iraqi specifications for asphalt cement. Consequently, HSNA can serve as an asphalt binder to produce asphalt mixtures for flexible paving construction. Notably, HSNA mixtures exhibited greater Marshall stability and stiffness index when compared to traditional mixtures. The results from indirect tensile strength (ITS) and tensile strength ratio (TSR) tests indicated that the 80NA mixture displayed the highest ITS values and a TSR of 81.36%, surpassing the TSR of the mixture incorporating petroleum asphalt by 0.57%.

Effect of Natural Bitumen on the Performance of Hot Asphalt Mixture‏

Globally, for more than a century, large quantities of asphalt binder have been consumed in the production of asphalt mixtures. There are two types of natural asphalt (NA) deposits in the Heet region: rock asphalt and sulphur spring asphalt. NA from sulphur springs was used in this study to assess NA performance and determine the suitability of using NA in local asphalt mixtures. The NA was treated by heating it to 163 °C for several hours. NA was subjected to laboratory testing after industrial treatments, and it was found that the physical properties of NA can conform to Iraqi specifications by heating it for 20 hours. The results showed that treated NA is better suited to hot climates because it is less temperature sensitive than traditional petroleum asphalt. NA was discovered to be highly effective in improving mechanical properties. In addition, the NA mixture had the highest indirect tensile strength values and a tensile strength ratio of 81.2%, which was 0.37% higher than the TSR of the conventional mix. NA will play an important role in the production of flexible pavements and provide a significant economic benefit without compromising the overall performance of the mixture because it is less expensive than conventional asphalt and is available in large quantities in Iraq.

Evaluation of eco-friendly asphalt mixtures incorporating waste plastic aggregates and additives: Magnesium, fly ash, and steel slag

This research explores the applicability of waste plastic aggregate (WPA) in the development of environmentally friendly asphalt mixtures, contributing to resource conservation, waste recycling, and the prevention of environmental issues associated with landfilling and incineration. Through experimental analysis of durability and common characteristics, the research investigates the optimal asphalt content (OAC) for practical implementation, particularly in substituting natural aggregates with waste plastic aggregates in asphalt mixture production. It examines the feasibility of producing asphalt mixtures by incorporating WPA and focuses on preventing microplastic generation using WPA in lower pavement layers. Additive materials, including Magnesium, fly ash, and steel slag powder, were used to enhance the properties of the mixtures. The experimental variation ratios in this research were assessed through a meticulous mixture design process involving the incorporation of WPA at varying contents (0%, 3%, 5%, 7%, and 10%) in both base (BB-2) and middle (MC-1) asphalt layers, enabling a comprehensive evaluation of the performance and characteristics of the resulting asphalt mixtures in comparison to control mixtures. Various tests, including wheel tracking, deformation strength, dynamic stability, crack resistance, and water resistance, are conducted to evaluate the performance of the mixtures. The findings indicate that 5% WPA can be seamlessly integrated into the asphalt mixture without external issues, and it exhibits satisfactory performance during the manufacturing process. The utilization of waste plastic fine aggregate results in non-uniform voids, while mixtures with 7% WPA fail to meet water resistance requirements. Coarse aggregates show better resistance to plastic deformation than fine aggregates, and mixtures with 5% WPA incorporating waste plastic fine aggregate demonstrate the highest resistance. Overall, this research provides valuable insights into the utilization of waste plastic aggregate in asphalt mixtures, highlighting its potential to enhance sustainability and pave the way for resource-saving practices in road construction, with the use of additive materials further improving the mixture properties.

Modern two-component modifiers inhibiting the aging process of road bitumen

The bitumen physicochemical properties of are constantly changing during both the production of asphalt mixtures and the service of road pavements. These changes involve bitumen hardening which consequently cause formation of defects and cracks in road pavements. Therefore, in recent years, prolonging road pavement life by inhibiting the bitumen aging process is a key trend in road engineering, bringing many economic, environmental and social benefits. In line with these trends, the main objective of this research was inhibition of short-term bitumen aging by two-component chitosan-based polymer composites containing ligands with different chemical structures, i.e. polyaniline, methacrylamide and 2-acrylamido-2-methylpropanesulfonic acid. This paper presents their effect on the TFOT aging process, as well as physicochemical and structural changes. Studies show that the strongest anti-aging properties are demonstrated by the chitosan:polyaniline composite. Its use at 2 % w/w allows it to maintain 90 % of the primary penetration value, increase the softening point by only 2°C and increase dynamic viscosity by 17% in comparison to non-aged modified bitumen. In addition, the use of the composite makes it possible to reduce the degree of bitumen components oxidation, which is seen from the reduction of carbonyl and sulfoxide indices by more than 33 % and 47 %, respectively.

Laboratory Evaluation of Porous Asphalt Mixtures with Cellulose Ash or Combustion Soot as a Filler Replacement

Porous asphalt (PA) mixtures have become a common and very useful pavement technology for preventing dangerous driving conditions in wet weather and as a permeable surface in permeable pavement systems due to their capacity to filter water. The increased social awareness of sustainability matters has expanded the interest in reducing the impact of construction materials on the environment, mainly by using recycled materials in their composition and, hence, reducing the depletion of raw materials. In this research, two innovative recycled filler materials, namely, cellulose ash (CA) and combustion soot (CS), have been used as a total filler replacement in PA mixtures to look for improved mechanical strengths and characteristics. Four different filler dosages were assessed for each filler material, and the produced PA mixtures were tested for their particle loss, water sensitivity, freeze–thaw durability, Marshall stability, resilient modulus and permeability in order to obtain a full picture of their performance. The obtained results showed that both filler materials, adequately dosed, can generate PA mixtures that significantly overcome reference mechanical values for PA mixtures that maintain adequate infiltration capacities to satisfy the main international standards, proving to be suitable replacements for conventional filler materials commonly used in asphalt mixture production.

Estimation and Sensitivity Analysis of Energy Consumption During the Production of Asphalt Mixtures

Estimation and Sensitivity Analysis of Energy Consumption During the Production of Asphalt Mixtures

Effect of recycled vegetable oil on the performance of nanomarl-modified asphalt mixtures

In response to the demand for a greener approach to pavement infrastructure and the economic benefits associated with alternative materials, the modification of neat binders has been a consistent focus. This research aimed to enhance the characteristics of asphalt binders and mixtures by incorporating recycled vegetable oil (RVO) and nanomarl. RVO was added to 60/70 penetration bitumen at concentrations of 1%, 3%, and 5% by weight, while nanomarl was kept constant at 5% by weight of the bitumen. Various physical, rheological, and microstructural properties of the modified binders were evaluated, including penetration, softening point, viscosity, rutting resistance, fatigue resistance, creep, stiffness, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Furthermore, the moisture susceptibility and rutting resistance performance of asphalt mixtures incorporating these modified binders were investigated through analyses of tensile strength ratio and Hamburg wheel tracking. The test results revealed that the incorporation of RVO in bitumen led to a gradual increase in the penetration value of the modified bitumen. Simultaneously, the softening point and viscosity of the modified bitumen decreased, indicating that the addition of oil rendered the modified bitumen softer. However, the inclusion of nanomarl in RVO-modified bitumen improved its viscoelastic behavior and positively influenced its rheological properties under both unaged and aged conditions. Specifically, the addition of 5% nanomarl resulted in reduced penetration value, increased softening point, viscosity, rutting resistance, fatigue resistance, creep stiffness, and improved relaxation behavior at low temperatures. The most favorable outcomes were observed when incorporating 1% RVO with 5% nanomarl. Moreover, SEM and FTIR analysis demonstrated successful blending of the additives into the bitumen, without any evidence of phase separation. This indicates a homogeneous distribution of the additives within the bitumen matrix.Practical application: The modification of bitumen with waste or recycled oils for the production of asphalt mixture has been successfully studied in numerous researches. However, this study introduces a novel approach by synergistically combining recycled vegetable oil (RVO) modification with the incorporation of nanomarl particles into asphalt mixture. The innovation aspect lies in the integration of two sustainable and environmentally friendly components, RVO and nanomral, to enhance asphalt performance. The findings offer a blueprint for incorporating sustainable materials and approaches in road construction projects. Pavement engineers can adopt the use of RVO modification and nanomarl particles to create longer-lasting and environmentally friendly asphalt pavements. In regions with challenging climatic conditions, the use of this modified asphalt can lead to improved infrastructure resilience. Roads built with these materials can better withstand temperature fluctuations. The integration of RVO and nanomarl particles offers improved performance, cost-effectiveness, reduced environmental impact, and also opens avenue for further exploration and optimization of asphalt mixtures incorporating innovative additives.

Influence of reclaimed asphalt pavement (RAP) and recycled asphalt shingle (RAS) binder availability on the composition of asphalt mixtures

Reclaimed asphalt pavements (RAP) and recycled asphalt shingles (RAS) are incorporated in the production of new asphalt mixtures to reduce cost, waste, and the consumption of virgin materials. The use of recycled asphalt materials (RAM) is limited by controlling agencies due to the uncertainties regarding their impacts on the volumetric composition and long-term performance of the asphalt mixtures. Recycled binder availability (RBA), which reflects the proportion of the recycled binder that is available to blend with virgin asphalt in an asphalt mixture, is currently neglected by the majority of mix design methods adopted by highway agencies, despite complete RBA being considered an unrealistic scenario. An incorrect assumption of the RBA in mixture design has important consequences on the inferred asphalt mixture volumetric properties, and consequently on the performance. A recently created method, so-called Availability Adjusted Mix Design (AAMD), proposes a revised interpretation of the volumetric properties of asphalt mixtures and design of the aggregate structure on the basis of partial RBA caused by agglomerations of RAM particles. The AAMD method is used in this study to evaluate the impacts of RBA on the volumetric properties of a diverse set of surface asphalt mixtures. The impacts of the RBA on the inferences of asphalt mixture composition are assessed for each mixture and the viability of using fixed RBA values for RAP and RAS sources in the state of North Carolina is assessed by comparing the inferred asphalt mixture composition yielded from the source-specific RBA versus the average RBA of the pool of recycled materials studied. The results show that the volumetric properties change considerably as a function of the assumed RBA, and the use of the AAMD becomes crucial for mixtures containing as little as 15 percent RAP and/or 4 percent or RAS. The use of a fixed RAS RBA value, calibrated as the average of a representative set of RAS stockpiles, versus the source-specific values has negligible impacts on the inferred volumetric properties of mixtures containing permissible RAS contents in North Carolina. Conversely, the use of source-specific RAP RBA values is recommended, which can be quantified through comparative sieve analysis of RAP and recovered RAP aggregate.

A Comparative Study of the Effect of Moisture Susceptibility on Polyethylene Terephthalate–Modified Asphalt Mixes under Different Regulatory Procedures

Water damage is one of the main causes of road deterioration during its lifespan, leading to a decrease in the structural and functional qualities of the road surface. Moreover, the management and disposal of polyethylene terephthalate (PET) bottles at the end of their lifecycle are becoming increasingly complex challenges. Hence, this study investigates the feasibility of incorporating crushed PET bottles into the production of asphalt mixtures, considering different PET quantities (6%, 10%, 14%, 18%, and 22%) and two incorporation processes in the mixture design (dry process and modified dry process). PET-modified mixtures‘ volumetric properties, Marshall parameters, and moisture susceptibility characteristics were evaluated and compared with PET-free asphalt mixtures. The results indicated that PET content significantly influences the properties being assessed, and the modified dry process yields a higher resistance to moisture susceptibility. Finally, the obtained TSR (tensile strength ratio) results based on European standards are compared with those obtained using American standards, in an aim to comprehend and assess the testing methods, result reliability, and applicability.

Study the Effect of using RAP in Warm Mix Asphalt Pavement.

Sustainability is providing the needs without compromising the ability of the strategical forming to meet their requirements. The production of warm asphalt mixtures using recycled pavements produces economic and environmentally friendly mixtures, which is the most important advantage of this work. This research aims to determine the effect of recycled asphalt concrete (RAP) on the indirect tensile strength of warm asphalt mixtures and Marshall Properties. Models of warm asphalt mixtures using Aggregate from the Al-Nibaay quarry, Asphalt with a degree of penetration (40-50) from the refinery of the cycle, and obtained Recycled asphalt concrete from Salah Al-Din Road, Al-Ameriya area in Baghdad are prepared. Use five ratios of (0, 10, 20, 30, and 40%) of recycled asphalt concrete. Marshall Design method is adopted to estimate the perfect existence of the asphalt cement for sample preparation. The mixtures properties, volumetric properties, and indirect tensile strength test are evaluated to assess bonding strength. Results show that the increase in the replacement percentage of RAP causes an increase in flow and air void and decreases the bulk density, voids in mineral aggregate (VMA), and voids filled with Asphalt (VFA). Stability increases with increased RAP content until it reaches its peak and falls. The highest stability value is at 30% RAP by 58%, about the indirect tensile strength test. The increase in the RAP ratio increases the tensile strength and the bonding between the components. So including RAP material in warm asphalt mixtures improves properties and meets performance requirements.