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Amongst various avenues being searched for solving the menace of increasing amount of plastic accumulation, its use in hot mix asphalt (HMA) is becoming popular. Several research studies have been conducted since the 1980s on the use of different types of waste plastics in asphalt mixtures through dry and wet processes. While it may seem 'simple' and 'attractive', incorporation of waste plastic in asphalt mixtures is plagued with many challenges. This paper summarizes the works of the available literature on the use of waste plastics in asphalt mixture. The selection of dry or wet process is highly dependent on type, density, size and melting point of waste plastic, to create a homogeneous mixture. Physical, rheological, and morphological properties of asphalt binder are effectively altered by the use of waste plastics. This is in turn is a function of various parameters such as type of plastic and base asphalt binder, dosages used, use of compatibilizers and other polymers, production process, etc. Similarly, the performance of waste plastic modified asphalt mixture is found to vary considerably. While the stiffness characteristics of HMA is improved by incorporation of waste plastic, more studies on in-field performance and environmental concerns are desirable. To make the use of waste plastic in HMA a 'success story', there is a need to carry out fundamental research to generate a unified solution. [ABSTRACT FROM AUTHOR]

This study conducted a thorough analysis of energy consumption and greenhouse gas (GHG) emissions in the production of hot mix asphalt. The primary sources of energy usage in asphalt mixes are the heating of aggregates, asphalt, and burners, with aggregate heating accounting for a remarkable 97% of the total energy consumption. The results indicate that low-temperature asphalt mixes offer significant benefits over conventional hot mix asphalt in terms of energy efficiency and GHG emissions, with reductions in carbon dioxide emissions ranging from 18% to 36% and energy savings between 15% and 87%. Additionally, the use of recycled asphalt pavement led to a 12% decrease in carbon dioxide emissions and a 15% reduction in energy consumption. The study further explored the effects of various fuel types on emissions, revealing that replacing fuel oil with natural gas can effectively diminish the carbon footprint of the production process. By optimizing production temperatures and selecting cleaner fuel alternatives, this research highlights the potential for considerable energy savings and emission reductions within the asphalt production sector. These strategies not only promote sustainable road construction practices but also play a vital role in environmental protection and climate change mitigation, advocating for the adoption of innovative technologies in asphalt pavement production. [ABSTRACT FROM AUTHOR]

In pavement construction, the need to utilize affordable fillers to improve asphalt mixture's performance cannot be overemphasized due to the rising cost of pavement construction occasioned by the skyrocketing cost of commonly used mineral fillers. It is germane to find alternative fillers that can not only enhance asphalt mixture's performance but also ensures that pavement construction cost is minimized. The present study, therefore, aimed to evaluate the performance of hot mix asphalt produced with calcined marl dust (CMD) used as partial replacement of a mineral filler, granite stone dust. The CMD, which was produced by pulverization and calcination of locally available marl, was blended with asphalt mixtures in varying percentages ranging from 0 to 100% by weight of the mineral filler. Thereafter, its effect on the bitumen content, moisture susceptibility and rutting resistance of hot mix asphalt were evaluated through, dynamic shear rheometer (DSR), indirect tensile strength and wheel tracking tests. The results from the study showed that 50% CMD significantly reduced moisture susceptibility, rutting potential, high creep rate, and low stiffness of hot mix asphalt. Furthermore, qualitative analysis such as Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) performed on the CMD indicated that there was complete dehydroxylation of the marl clay minerals and also the presence of calcite, silica and alumina in the CMD. This greatly suggests that the pozzolanic content of the CMD improved the performance of the hot mix asphalt. Lastly, the SEM micrograph also revealed the rough and angular morphology of the CMD which may have contributed to the reduction in crack propagation and adhesion of the asphalt mixtures. [ABSTRACT FROM AUTHOR]

MonoTrapTM was introduced in 2009 as a novel miniaturized configuration for sorptive sampling. The method for the characterization of volatile organic compound (VOC) emission profiles from hot mix asphalt (HMA) consisted of a two-step procedure: the analytes, initially adsorbed into the coating in no vacuum- or vacuum-assistance mode, were then analyzed following an automated thermal desorption (TD) step. We took advantage of the theoretical formulation to reach some conclusions on the relationship between the physical characteristics of the monolithic material and uptake rates. A total of 35 odor-active volatile compounds, determined by gas chromatography-mass spectrometry/olfactometry analysis, contributed as key odor compounds for HMA, consisting mainly of aldehydes, alcohols, and ketones. Chemometric analysis revealed that MonoTrapTM RGC18-TD was the better coating in terms of peak area and equilibrium time. A comparison of performance showed that Vac/no-Vac ratios increased, about an order of magnitude, as the boiling point of target analytes increased. The innovative hybrid adsorbent of silica and graphite carbon monolith technology, having a large surface area bonded with octadecylsilane, showed effective adsorption capability, especially to polar compounds. [ABSTRACT FROM AUTHOR]

Sustainability plays an integral role in ensuring the continued existence of life on Earth and the protection of the natural environment. The recycling process is one of the most significant methods through which this strategy can be implemented. The potential environmental benefits of recycled concrete aggregates and polymer waste have attracted considerable interest within the asphalt industry. The present study focuses on the recycling of two materials to create asphalt mixtures. The first of these is polypropylene, which is mixed with asphalt cement at weight rates of 2%, 4%, and 6%. The second is treated and untreated Recycled Concrete Aggregate (RCA), which is substituted with coarse aggregate at weight rates of 20%, 40%, and 60%. The experimental work comprised the identification of the optimum asphalt content through the utilization of the Marshall design approach, the assessment of Marshall and volumetric characteristics, and the evaluation of moisture susceptibility through the measurement of Indirect Tensile Strength (ITS) and compressive strength. The findings indicated that all mixtures containing recycled polypropylene polymers and treated/untreated RCA exhibited a higher Tensile Strength Ratio (TSR) of approximately 6.1-14.7% and compressive strength of approximately 3.1-17.6% compared to control asphalt mixtures. This suggests that the mixture's resilience against moisture damage has been enhanced. [ABSTRACT FROM AUTHOR]

Asphalt pavements make up a majority of the essential transportation systems in the US. Asphalt mixtures age and degrade over time, reducing the pavement performance. Pavement performance critically depends on the aging of asphalt binder. The aging of asphalt binder during construction is traditionally modeled by rolling thin film oven (RTFO) testing, while aging during service life is modeled by pressure aging vessel (PAV) testing. Comparing these models to the aging of binders in actual pavements is limited because, to be used for current testing, binders must be separated from the pavement’s aggregate by solvent extraction. Solvent extraction will, at least in part, compromise the structural integrity of asphalt binder samples. Spin-lattice NMR relaxometry has been shown to nondestructively evaluate asphalt properties in situ through the analysis of hydrogen environments. The molecular mobility of hydrogen environments and with it the stiffness of asphalt binder samples can be determined by characteristic T1 relaxation times, indicating the complexity of asphalt-binder aging. In this study, two laboratory-generated asphalt mixtures, a failed field sample, and several laboratory-aged binder samples are compared by NMR relaxometry. NMR relaxometry was found to be able to differentiate between asphalt samples based on their binder percentage. According to the relaxometry findings, the RTFO binder aging compared favorably to the 6% laboratory-mixed sample. The PAV aging, however, did not compare well to the relaxometry results found for the field-aged sample. The amount of aggregate was found to have an influence on the relaxation times of the binder in the mixed samples and an inverse proportionality of the binder content to the primary NMR relaxation time was detected. It is concluded that molecular water present in the pores of the aggregate material gives rise to such a relationship. The findings of this study lay the foundation for nondestructive asphalt performance evaluation by NMR relaxometry.

Asphalt pavements make up a majority of the essential transportation systems in the US. Asphalt mixtures age and degrade over time, reducing the pavement performance. Pavement performance critically depends on the aging of asphalt binder. The aging of asphalt binder during construction is traditionally modeled by rolling thin film oven (RTFO) testing, while aging during service life is modeled by pressure aging vessel (PAV) testing. Comparing these models to the aging of binders in actual pavements is limited because, to be used for current testing, binders must be separated from the pavement's aggregate by solvent extraction. Solvent extraction will, at least in part, compromise the structural integrity of asphalt binder samples. Spin-lattice NMR relaxometry has been shown to nondestructively evaluate asphalt properties in situ through the analysis of hydrogen environments. The molecular mobility of hydrogen environments and with it the stiffness of asphalt binder samples can be determined by characteristic T1 relaxation times, indicating the complexity of asphalt-binder aging. In this study, two laboratory-generated asphalt mixtures, a failed field sample, and several laboratory-aged binder samples are compared by NMR relaxometry. NMR relaxometry was found to be able to differentiate between asphalt samples based on their binder percentage. According to the relaxometry findings, the RTFO binder aging compared favorably to the 6% laboratory-mixed sample. The PAV aging, however, did not compare well to the relaxometry results found for the field-aged sample. The amount of aggregate was found to have an influence on the relaxation times of the binder in the mixed samples and an inverse proportionality of the binder content to the primary NMR relaxation time was detected. It is concluded that molecular water present in the pores of the aggregate material gives rise to such a relationship. The findings of this study lay the foundation for nondestructive asphalt performance evaluation by NMR relaxometry. [ABSTRACT FROM AUTHOR]

A recently used material that shows environmental and technical advantages for use as an asphalt binder modifier is biochar (BC). Different biomasses can be converted into BC by pyrolysis. One agro-industrial biomass that is abundant in copious quantities is oil palm mesocarp fiber (OPMF) obtained from African palm cultivation. In the present study, the use of a BC obtained from OPMF (BC-OPMF) as a modifier of asphalt binder (AC type) to produce a hot mix asphalt (HMA) was evaluated. This type of BC has not been investigated or reported in the reference literature as a binder and/or asphalt mix modifier. Initially, AC was modified with BC in three ratios (BC/AC = 5, 10, and 15%, with respect to mass) to perform penetration, softening point, and rotational viscosity tests; rheological characterization at high and intermediate temperatures; and scanning electron microscope (SEM) visualization. Based on this experimental phase, BC/AC = 10% was chosen to manufacture the modified HMA. Resistance parameters under monotonic loading (stability—S, flow—F, S/F ratio of the Marshall test, and indirect tensile strength in dry—ITSD and wet—ITSC conditions) and cyclic loading (resilient modulus, permanent deformation, and fatigue resistance under stress-controlled conditions) were evaluated on the control HMA (AC unmodified) and the modified HMA. Additionally, the tensile strength ratio (TSR) was calculated to evaluate the resistance to moisture damage. Abrasion and raveling resistance were evaluated by performing Cantabro tests. BC-OPMF is shown to be a sustainable and promising material for modifying asphalt binders for those seeking to increase stiffness and rutting resistance in high-temperature climates, resistance to moisture damage, raveling, and fatigue without increasing the optimum asphalt binder content (OAC), changing the volumetric composition of the HMA or increasing the manufacturing and construction temperatures. [ABSTRACT FROM AUTHOR]

This study evaluated the individual and cumulative impact of different design factors on moisture damage of hot-mix asphalt (HMA) using the modified Lottman test. This study considered five different types of design aggregate gradations (DAG), three binder types, and three levels of compactive effort. To evaluate the significance of the influential factors that affected the moisture sensitivity of the mix, statistical analysis was performed. This study also investigated the influence of volumetric parameters of the bituminous mixes on moisture damage. The correlation of different design factors and various volumetric parameters with the tensile strength ratio (TSR) was further investigated through analysis using the Pearson correlation coefficient. The need for this investigation arises from the scarcity of comprehensive studies examining the individual and combined effects of various factors and the impact of volumetric parameters on moisture susceptibility. Additionally, linear regression models were developed to predict TSR based on the design factors and volumetric parameters considered in the study. The final model showed a close fit, with low mean absolute percentage error (MAPE=0.931) and a good coefficient of determination (R2=0.752). Moreover, based on the tested mixtures, the study establishes a threshold value of dry indirect tensile strength (ITSdry=750 kPa) and wet indirect tensile strength (ITSwet=650 kPa), along with TSR (= 0.85). [ABSTRACT FROM AUTHOR]

This paper evaluates the strength performance of hot mix asphalt produced with High Density Polyethylene (HDPE)-modified bitumen and Reclaimed Asphalt Pavement (RAP) which is partially replacing virgin aggregates. Asphalt Institute blending chart was used to determine the quantity of Reclaimed Asphalt Pavement (RAP) incorporated into the mixture. Thermo-gravimetric Analysis and Differential Thermal Analysis (TGA/DTA) were used to determine thermal stability of the High Density Polyethylene (HDPE). Fourier Transform Infrared (FTIR) was used for characterization of the HDPE, bitumen and modified bitumen. Physical test conducted on the RAP and virgin aggregates in accordance with American Society of Testing Materials (ASTM) standards revealed that the aggregates are adequate for use in asphalt production. Marshall method of mix design was adopted for the hot mix asphalt production and testing. With respect to the threshold, the results of Marshall stability showed a 6% increase in the strength of the asphaltic mixture modified with 10% High Density Polyethylene (HDPE). Other Marshall properties tested also showed improvements. Scanning Electron Microscopy and Energy Dispersive X-ray Spectrometry (SEM/EDS) were used for micro-structural examination and composing elements analysis of the asphaltic mixture, respectively. Fibermetric analysis was used to explore the fiber content and pores within the mixture. [ABSTRACT FROM AUTHOR]

In this study, the benefits and feasibility of incorporating Polyethylene Terephthalate (PET) into Flexible pavement were evaluated. The study aims to identify new ideas on recycling plastic wastes and thereby improving overall sustainability. The Samples were prepared by adding PET with an increasing concentration level along with optimum asphalt content with a percentage by weight of 3.5%, 4.0%, 4.5%, 5.0%, 5.5% and 6%. Multiple tests were conducted on Natural aggregates including Resistance to degradation of aggregates by Abrasion and Impact, Specific Gravity and Abrasion of coarse aggregates, and Impact Value of Aggregates. Similarly, the tests conducted on asphalt include the specific gravity of semi-solid bituminous material, the ductility of bituminous material, the flash point and softening point of asphalt, and the penetration grade of bituminous material. Rutting potential of the optimum asphalt, Plastic mix Was evaluated by increasing the frequency of load cycles from 0 to 5000 cycles. Furthermore, the effect of asphalt and plastic content on the density, Flow, voids, and stability were also analysed. It was found that the addition of PET resulted in improved stability by more than 50% specifically 52%, while 70% improvement was observed in flow characteristics of Hot Mix Asphalt. However, a slight change in density was observed. The sample also showed a reduction in rut depth by more than 40% of the mix. [ABSTRACT FROM AUTHOR]

Electric arc furnace slag (EAFS) is a viable alternative in asphalt mixtures due to its favourable mechanical properties. This study examines the impact of EAFS content and bitumen film thickness (TF) on the fatigue performance of asphalt mixtures. Mixtures with varying levels of EAFS replacement were designed, and their mechanical properties were evaluated through indirect tensile strength and stiffness tests, followed by fatigue tests using the four-point bending method and EBADE (Strain Sweep Test). The results indicated that mixtures with EAFS exhibited increased stiffness, but fatigue performance decreased at high strain levels. At low strain levels, EAFS mixtures performed similarly or better than the control. HMA_GL had the highest TF (13.97 μm), followed by HMA_GS (13.60 μm), HMA_SL (12.66 μm), and HMA_SS (11.77 μm), showing that as the EAFS content increases, the TF decreases. This finding was verified through Digital Image Analysis. This decrease in TF is due to the high porosity and roughness of the EAFS, which in turn reduces the effective bitumen (Pbe) in the mixture. HMA_SL*, with a TF equal to the control, demonstrated a 22 % improvement in fatigue performance compared to HMA_SL. In the EBADE tests, HMA_GL achieved 44.69 MJ/m3 of dissipated energy, HMA_GS 31.55 MJ/m3, HMA_SL 34.45 MJ/m3, and HMA_SS 35.54 MJ/m3. The improved HMA_SL* recorded 42.15 MJ/m3, nearly matching the control. EBADE results confirmed that higher EAFS content increased initial stiffness, but the complex modulus (|E*|) decreased more rapidly as deformation increased. These results are consistent with the stiffness tests. These findings suggest that EAFS can successfully replace natural aggregates in asphalt mixtures, with a moderate increase in bitumen content recommended to improve fatigue performance.

In recent years, there have been unprecedented developments in artificial intelligence. Object detection, voice recognition, face recognition etc. are some of the artificial intelligence applications. In this study, an auxiliary method for the automatic detection of cracks, one of the main deterioration problems on highways, is proposed. The crack formation of hot mix asphalts is investigated with an image processing method modeled with Attention SegNet architecture. Styrene-butadiene-styrene (SBS), the most widely used additive in bitumen modification, was used at 2 %, 3 %, and 4 % ratios to modify 50/70 bitumen. Semi-circular asphalt specimens obtained with SBS modified bitumen were subjected to a semicircular bending (SCB) test and fracture performance was investigated. The effects of different temperature, notch size and additive on crack detection performance are evaluated. In the experimental study, maximum load, fracture energy, fracture toughness (KIC) values were obtained at low temperature, and resistance values against crack propagation were obtained by applying the J-integral method at intermediate temperature. The results demonstrated that with the addition of SBS, the fracture strength and maximum load values increased at each temperature value, with the 4 % SBS mixture offering the highest performance. Moreover, the image segmentation performed with SegNet provided high accuracy and precision values for cracks. It was observed that the accuracy values of the image processing methods decreased at low temperature, while at high temperature, higher accuracy values were obtained as the cracking rate.

A pilot project for the inclusion of recycled asphalt shingles (RAS) in hot mix asphalt (HMA) was built on State Route 49 in El Dorado County in November 2021. Four mixes were included in short test sections: (1) a control mix with no RAS or recycled asphalt pavement (RAP), (2) a typically used mix with 10% RAP that was also used for construction of the rest of the overall project, (3) a mix with 3% RAS, and (4) a mix with 10% RAP and 3% RAS. This technical memorandum presents the laboratory test results from plant mix produced for job mix formula (JMF) verification and from two quality assurance (QA) samples taken during test section construction as well as observations of plant production and construction. The results showed that the mixes submitted for JMF verification and tested as part of QA all met the two performance-related specifications. Most of the QA samples had binder and mix testing results that were similar to or better than those of the JMF verification samples, though there were exceptions. There were no major problems during production or placement of the mixes. The existing roadway has highly variable thicknesses of remaining HMA after milling, and the remaining original HMA has transverse, wheelpath, and block cracks.

Using existing resources more efficiently and effectively becomes important currently. The question of how to make the best use of resources arises in the choice between constructing new roads and improving deteriorated existing roads. It is also important to reduce the amount of consumption and cost of materials. This has emerged the need to use waste materials by recycling and reusing. In this study, a new hot-mix asphalt (HMA) mixture was developed using recycled asphalt pavement (RAP), which was obtained by excavating the surface of a road at the end of its service life, together with a waste material namely natural pozzolan (NP). The final obtained mixture was used as a wear layer on an active highway. Core specimens were extracted from the paved layer for one year and subjected to dynamic and mechanical laboratory tests. Adding NP improved the resistance of the HMA mixture under heavy seasonal effects and traffic loads. In addition, NP increased the tensile strength, making the HMA mixture more resistant to deformation than control and RAP HMA mixtures. Dynamic creep test results showed that the control asphalt mixture had the most deformation and that the RAP mixture with NP had the least. According to the laboratory results, NP addition increased the stability value of the control mixture by 40%. Especially in cold seasons, the role of NP was more evident. In the performance tests that were applied on core samples taken from the field, ITS values for September increased by 98%, and the deformation values obtained as a result of the dynamic creep test decreased by 12%. In summary, adding NP to RAP HMA improves the performance of the pavement and the cost-effectiveness of the environmentally friendly use of RAP in HMA. [ABSTRACT FROM AUTHOR]

In recent time, more polyvinyl chloride (PVC) plastic are produced than what is currently being recycled, that contributes to the volume of waste. This occurrence prompted the exploration of polymer modified bitumen (PMB) to address the waste concern and thereby cuts cost in bituminous mix and improves pavement performance. This research evaluated the strength properties of asphalt mixture produced with polyvinyl chloride modified bitumen. Marshall method of mix design was used in the production of hot mix asphalt (HMA). Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR) and Energy Dispersive X-Ray Spectrometry (EDS), used for microstructural examination and elemental analysis. These materials conform with its physical properties and characteristics. The shredded, grinded plastic revealed high binding properties when blend with bitumen. The percent incorporated was 2 - 10% PVC content and the Optimum Bitumen Content obtained was 10%, at 9.57kN for stability. The modified bitumen for penetration recorded at 68mm, which conformed with 60/70 grade bitumen, softening point recorded at 52oC, ductility was recorded at 107cm, specific gravity at 1.02, flash and fire point at 294oC and 306oC, solubility at 97% respectively. The properties were satisfactorily for grade 60/70 bitumen at 4% PVC by weight and be used as bitumen modifier for heavy traffic condition. Polyvinyl Chloride modified at 8 - 10%, be used at cold climates, while 2, 4, 6% PVC modified be used in warm regions. Therefore, the experiment proved these materials with characteristics, stability and stiffness be used for pavement constructions.

The primary goal of this study is the design and construction of semi-flexible pavement (SFP) mixture in accordance with the engineering and mechanical criteria. This study involves the use of a range of gradation curves, air void contents, cellulose and synthesized fibers, and neat and modified asphalt binders to prepare the open-graded asphalt (OGA) mixtures. To analyze the characteristics of these mixtures, a variety of test, namely binder drainage, semi-circular bending (SCB), Cantabro, wheel tracking, indirect tensile strength (ITS), and permeability tests were conducted. Additionally, to analyze the prepared grouting material, flexural strength, compressive strength, and fluidity tests were conducted. In the final stage, SFP was compared to HMA in terms of engineering characteristics and performance. According to the results, SFP was more resistant to skid, rutting, fire, and moisture damage, while HMA had a better performance in fracture tests, including SCB test. According to the results of the mechanical performance tests conducted on OGA mixtures, the highest and lowest values for air void content to achieve the highest mechanical performance level were 30%–35% and 25%, respectively. Also, based on the laboratory results, it was determined that the required void ratio for constructing OGA mixtures was 24%–26% based on the bitumen type and fibers amount in the mixture. Finally, SFP mixture can be regarded as a viable alternative to common pavements thanks to its high resistance to rutting and moisture damage, long freezing-thawing fatigue life, and adequate fire and skid resistance.

Recently, researchers have been moving toward using local waste as an alternative for construction materials. Using these wastes to pave roads is one of the essential recycling methods, which aims to reduce the consumption of natural resources and environmental pollution resulting from the difficulty of decomposing these wastes. In the Middle East, especially in Iraq, Date Palm fiber is widely available as a local waste material. The aim of this research is to evaluate the performance of a developed asphalt mixture with palm leaf powder (PLP) as a partially substituted mineral filler. The Marshall mix design method produced the asphaltic mixes with ordinary Portland cement and PLP as mineral fillers. PLP was included in three rates denoted by 10, 20, and 30% by the weight of the mineral filler. Marshal stability, flow, bulk specific gravity, air voids, voids in mineral aggregates, voids filled with the binder, the indirect tensile strength, and the indirect tensile strength ratio of the PLP mixture were measured and compared with those of the conventional asphalt mixture. Based on the findings of this study, 20% of the Portland cement could be replaced with PLP, at which all of the properties of the enhanced mixture met the requirements of the Iraqi specifications. Then, the asphalt mix with 20% PLP was tested to assess its resistance against fatigue cracks. The results support the usage of waste PLP in pavement construction, enhancing its properties, which would also be very effective as an eco-friendly material.

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.

I In the scope of the study, the use of waste phonolite (PW) obtained from phonolite wastewater formed during the processing of phonolite stone blocks as filler in hot-mix asphalt (HMA) was investigated. For this purpose, samples were produced with 4 %, 5 %, and 6 % PW mineral filler and 5 % limestone (LS) mineral filler. Phonolite supplied as waste was sieved through a sieve no 200 and made ready for use as a filler. HMA specimens were prepared with PW and LS at the rates of 3.5 %, 4 %, 4.5 %, 5 %, 5.5 %, and 6 % bitumen. For each filler ratio, a bituminous hot mix design was made by the Marshall method and optimum bitumen ratios (OBR) were determined. Bituminous hot mixture specimens were prepared based on OBR. Retained Marshall stability (RMS) test, indirect tensile strength (ITS), and moisture damage resistance tests and Marshall stability (MS) test after the freeze-thaw (F-T) cycle was applied to the prepared Marshall samples. The results obtained were evaluated according to the Turkish Highway Technical Specification (HTS). As a result, it was determined that the PW could be used as filler in HMA under low-intensity traffic.

In this study, the mechanical behavior and resistance to moisture damage of hot mix asphalt (HMA) concrete with the addition of Milled Carbon Fiber (MCF) were experimentally investigated. For this purpose, the gradation curve within the boundaries of the Turkish highway construction specifications (HTS) has been determined. By keeping the determined gradation constant, MCF was added at different rates (1 %, 1.5 %, 2 %, 2.5 %, 3 %) by weight of the mixture. In the study, first, optimum bitumen ratios (OBR) of pure control samples (0 %-Control) without MCF and mixtures with MCF additives were determined by using the Marshall design method. To determine the OBR, samples were prepared with bitumen content of 3.5 %, 4 %, 4.5 %, 5 %, 5.5 %, and 6 % at each carbon additive ratio. The mixture samples prepared using the specified OBRs were subjected to Marshall stability (MS) and flow, as well as to retained Marshall stability (RMS), indirect tensile strength (ITS), and moisture damage resistance tests. According to the test results, it was observed that the MS values of the asphalt concrete with MCF additives increased at certain carbon additive ratios, while the flow values decreased compared to the witness sample. It was determined that the RMS and indirect tensile strength ratio (TSR) values of hot mixes with MCF-added bitumen increased and the moisture damage resistance of the mixes increased. As a result, when the optimum MCF ratio determined for the wearing course is used, it is thought that the engineering properties of HMA will improve.

This study conducted a thorough analysis of energy consumption and greenhouse gas (GHG) emissions in the production of hot mix asphalt. The primary sources of energy usage in asphalt mixes are the heating of aggregates, asphalt, and burners, with aggregate heating accounting for a remarkable 97% of the total energy consumption. The results indicate that low-temperature asphalt mixes offer significant benefits over conventional hot mix asphalt in terms of energy efficiency and GHG emissions, with reductions in carbon dioxide emissions ranging from 18% to 36% and energy savings between 15% and 87%. Additionally, the use of recycled asphalt pavement led to a 12% decrease in carbon dioxide emissions and a 15% reduction in energy consumption. The study further explored the effects of various fuel types on emissions, revealing that replacing fuel oil with natural gas can effectively diminish the carbon footprint of the production process. By optimizing production temperatures and selecting cleaner fuel alternatives, this research highlights the potential for considerable energy savings and emission reductions within the asphalt production sector. These strategies not only promote sustainable road construction practices but also play a vital role in environmental protection and climate change mitigation, advocating for the adoption of innovative technologies in asphalt pavement production.

MonoTrapTM was introduced in 2009 as a novel miniaturized configuration for sorptive sampling. The method for the characterization of volatile organic compound (VOC) emission profiles from hot mix asphalt (HMA) consisted of a two-step procedure: the analytes, initially adsorbed into the coating in no vacuum- or vacuum-assistance mode, were then analyzed following an automated thermal desorption (TD) step. We took advantage of the theoretical formulation to reach some conclusions on the relationship between the physical characteristics of the monolithic material and uptake rates. A total of 35 odor-active volatile compounds, determined by gas chromatography-mass spectrometry/olfactometry analysis, contributed as key odor compounds for HMA, consisting mainly of aldehydes, alcohols, and ketones. Chemometric analysis revealed that MonoTrapTM RGC18-TD was the better coating in terms of peak area and equilibrium time. A comparison of performance showed that Vac/no-Vac ratios increased, about an order of magnitude, as the boiling point of target analytes increased. The innovative hybrid adsorbent of silica and graphite carbon monolith technology, having a large surface area bonded with octadecylsilane, showed effective adsorption capability, especially to polar compounds.

The effect of polymer composition on hot mix asphalt (HMA) is the primary focus of this research. The primary goal is to examine how temperature affects HMA's mechanical characteristics and performance, especially concerning polymer concentration. Polymer composition and modifications to HMA, including synthetic rubber and high-density polyethylene (HDPE), are the object of this research. Optimizing HMA polymer mix to improve durability, load-bearing capacity, and structural integrity is the study's key issue. The study also seeks to understand the intricate interaction between polymer concentration and HMA parameters, such as compressive strength, modulus, and stress. The research findings indicate that the maximum load of 68.169 kN was achieved with a mixture containing 5 % synthetic rubber at a temperature of 200 °C. The material exhibited stiffness and resistance to deformation, with an average crack size of 0.01 kN/mm² and a modulus value of 0.309 kN/mm². According to the Marshall function, the optimal blend consists of 5 % asphalt mixed at 175 °C. The results indicate that polymer mix considerably affects HMA's mechanical properties, particularly load-bearing capacity and deformation resistance. To optimize HMA performance, polymer content and temperature must be optimized. The results show that HMA with 5 % synthetic rubber under specified temperature settings has better mechanical qualities, including load-bearing capacity and stiffness. These findings help optimize polymer composition for HMA performance. These findings can be used to create more lasting and eco-friendly paving solutions. Road engineers and designers can extend asphalt pavement life and reduce environmental effects by adjusting the HMA polymer mix and temperature [ABSTRACT FROM AUTHOR]

Agro industries have produced huge amounts of waste, influencing the environment. Palm oil clinker (POC), routinely dumped from Malaysian palm oil mills, is one of these waste products. This research investigates the feasibility of using it as a filler substitute in hot mix asphalt (HMA) as an alternative avenue to utilize this waste. The waste POC powder (POCP) is comparable to the properties of the traditional fillers used-granite stone dust (GSD), according to physiochemical analysis. The POCP passes through 75 µm sieve, and 6% (w/w) of the filler was substituted by 0%, 20%, 40%, 60%, 80%, and 100% (w/w) of the GSD. HMA mixes were prepared for various percentages using the Marshall mix design to evaluate their respective optimum bitumen contents (OBC). Subsequently, at OBC, the influence of POCP on the HMA volumetric, Marshall properties, Cantabro test resilient modulus, and moisture damage tests was investigated. The study revealed that all POCP mixtures improve performance in terms of stability, stiffness, and higher resistances against moisture damage than the control mixture. The improvement could be attributed to the synergistic influence of POCP pozzolanic reaction and fineness, resulting in a thicker refined mastic between POCP and bitumen, producing more durable HMA. However, based on the study findings, 80% of POCP filler for HMA mixes can be considered the optimal content to improve its properties. In conclusion, the study depicts the viability of utilizing POCP as a replacement for conventional filler to promote sustainability and provides a proper channel for its disposal. [ABSTRACT FROM AUTHOR]

Most of the roads in Algeria are flexible pavements, the main component of which is asphalt concrete. Asphalt concrete aggregates made from crushed stone are now expensive and unavailable near roads, favoring the use of local materials such as dune sand, which is abundant in southern Algeria. The aim of this work is to study the rheological behavior of asphalt concrete, which is partially made of dune sand, as an alternative to crushed sand currently used. The effect of dune dosage on the rheological properties of concrete, in particular its compaction and rutting resistance, was determined using several formulations. To this end, various asphalt mixtures were tested on different dune sand grains using the Super pave rotary shear compaction (GSC) test by means of a rotary shear press to quantify their effect on compaction. These same asphalt mixtures were used to manufacture inserts for rutting tests. According to the results obtained, very acceptable values of resistance to rutting were achieved with 05 to 15% of dune sands compared to the reference concrete. [ABSTRACT FROM AUTHOR]

The primary goal of this study is the design and construction of semi-flexible pavement (SFP) mixture in accordance with the engineering and mechanical criteria. This study involves the use of a range of gradation curves, air void contents, cellulose and synthesized fibers, and neat and modified asphalt binders to prepare the open-graded asphalt (OGA) mixtures. To analyze the characteristics of these mixtures, a variety of test, namely binder drainage, semi-circular bending (SCB), Cantabro, wheel tracking, indirect tensile strength (ITS), and permeability tests were conducted. Additionally, to analyze the prepared grouting material, flexural strength, compressive strength, and fluidity tests were conducted. In the final stage, SFP was compared to HMA in terms of engineering characteristics and performance. According to the results, SFP was more resistant to skid, rutting, fire, and moisture damage, while HMA had a better performance in fracture tests, including SCB test. According to the results of the mechanical performance tests conducted on OGA mixtures, the highest and lowest values for air void content to achieve the highest mechanical performance level were 30%e35% and 25%, respectively. Also, based on the laboratory results, it was determined that the required void ratio for constructing OGA mixtures was 24%e26% based on the bitumen type and fibers amount in the mixture. Finally, SFP mixture can be regarded as a viable alternative to common pavements thanks to its high resistance to rutting and moisture damage, long freezing-thawing fatigue life, and adequate fire and skid resistance. [ABSTRACT FROM AUTHOR]

This study investigated the positive effect of the combined use of recycled asphalt shingles (RASs) and municipal solid waste incineration (MSWI) bottom ash (B.A.) in asphalt concrete, which contributes to enhanced sustainability in pavement engineering. In addition, unlike traditional approaches that employ individual recycling material in hot mix asphalt (HMA), the combined use of the two waste materials maximizes the mechanical performance of the asphalt mixture. The addition of RAS (with 30–40% aged binder) as an additive generally enhances the strength/stiffness of the asphalt mixture. The high porosity/absorption of MSWI BA results in an additional amount of liquid asphalt binder in the mixture. As an admixture, RAS could supply the additional asphalt binder in the mixture when MSWI BA is used as an aggregate replacement. This research was conducted in two phases: (1) to examine the effect of MSWI BA alone and its optimal asphalt content (OAC), and (2) to assess the combined effect of B.A. and RAS in HMA. Multiple laboratory testing methods were employed for the mechanical performance investigation, including the Marshall stability test, rutting test, and indirect tensile test. The testing results show that the 20% B.A. replacement exhibits the best performance and that it requires an additional asphalt binder of 1.1%. For the combined use of MSWI BA and RAS, 5% RAS shows the best mechanical performance. All mixtures that contain the B.A. and RAS show greater strength than the control specimen (regular HMA). [ABSTRACT FROM AUTHOR]

In the scope of the study, the use of waste phonolite (PW) obtained from phonolite wastewater formed during the processing of phonolite stone blocks as filler in hot-mix asphalt (HMA) was investigated. For this purpose, samples were produced with 4 %, 5 %, and 6 % PW mineral filler and 5 % limestone (LS) mineral filler. Phonolite supplied as waste was sieved through a sieve no 200 and made ready for use as a filler. HMA specimens were prepared with PW and LS at the rates of 3.5 %, 4 %, 4.5 %, 5 %, 5.5 %, and 6 % bitumen. For each filler ratio, a bituminous hot mix design was made by the Marshall method and optimum bitumen ratios (OBR) were determined. Bituminous hot mixture specimens were prepared based on OBR. Retained Marshall stability (RMS) test, indirect tensile strength (ITS), and moisture damage resistance tests and Marshall stability (MS) test after the freeze-thaw (F-T) cycle was applied to the prepared Marshall samples. The results obtained were evaluated according to the Turkish Highway Technical Specification (HTS). As a result, it was determined that the PW could be used as filler in HMA under low-intensity traffic. [ABSTRACT FROM AUTHOR]

In this study, the mechanical behavior and resistance to moisture damage of hot mix asphalt (HMA) concrete with the addition of Milled Carbon Fiber (MCF) were experimentally investigated. For this purpose, the gradation curve within the boundaries of the Turkish highway construction specifications (HTS) has been determined. By keeping the determined gradation constant, MCF was added at different rates (1 %, 1.5 %, 2 %, 2.5 %, 3 %) by weight of the mixture. In the study, first, optimum bitumen ratios (OBR) of pure control samples (0 %-Control) without MCF and mixtures with MCF additives were determined by using the Marshall design method. To determine the OBR, samples were prepared with bitumen content of 3.5 %, 4 %, 4.5 %, 5 %, 5.5 %, and 6 % at each carbon additive ratio. The mixture samples prepared using the specified OBRs were subjected to Marshall stability (MS) and flow, as well as to retained Marshall stability (RMS), indirect tensile strength (ITS), and moisture damage resistance tests. According to the test results, it was observed that the MS values of the asphalt concrete with MCF additives increased at certain carbon additive ratios, while the flow values decreased compared to the witness sample. It was determined that the RMS and indirect tensile strength ratio (TSR) values of hot mixes with MCF-added bitumen increased and the moisture damage resistance of the mixes increased. As a result, when the optimum MCF ratio determined for the wearing course is used, it is thought that the engineering properties of HMA will improve. [ABSTRACT FROM AUTHOR]

The influence of aggregate properties and natural rubber latex (NRL) additive on the performance of natural rubber modified asphalt (NRMA) concrete mixtures was investigated. The NRMA mixtures were prepared using three types of aggregate (granite, limestone, and basalt), asphalt cement AC60/70 and NRL with different rubber to binder (R/B) ratios of 3%, 5%, and 7%. A series of laboratory tests including Marshall stability and flow, indirect tensile strength, indirect tensile fatigue, resilient modulus, wheel tracking test, dynamic creep, and skid resistance tests were conducted to investigate the mechanical properties and mechanistic performance of the NRMA mixtures. Statistical analysis was performed using the NLOGIT software program to evaluate the influence factors including strength, shape, and chemical properties of aggregate and R/B ratio. The R/B ratio of 3% was found to be the optimum value which provided the best mechanical properties and performance. The strength parameters and mineral compound were found to control the Marshall stability. As such, the NRMA mixtures with basalt and granite of high Marshall stability led to the high resilient modulus, rutting resistance, and permanent deformation. Because of the good strength and shape parameters of granite, the NRMA mixture with granite indicated a significant rate of improvement of fatigue life compared with the NRMA mixtures with other aggregates. Limestone's predominant mineral compounds (CaO, MgO, and SiO2) were found to influence the indirect tensile strength and skid resistance of NRMA mixtures. [ABSTRACT FROM AUTHOR]

A recently used material that shows environmental and technical advantages for use as an asphalt binder modifier is biochar (BC). Different biomasses can be converted into BC by pyrolysis. One agro-industrial biomass that is abundant in copious quantities is oil palm mesocarp fiber (OPMF) obtained from African palm cultivation. In the present study, the use of a BC obtained from OPMF (BC-OPMF) as a modifier of asphalt binder (AC type) to produce a hot mix asphalt (HMA) was evaluated. This type of BC has not been investigated or reported in the reference literature as a binder and/or asphalt mix modifier. Initially, AC was modified with BC in three ratios (BC/AC = 5, 10, and 15%, with respect to mass) to perform penetration, softening point, and rotational viscosity tests; rheological characterization at high and intermediate temperatures; and scanning electron microscope (SEM) visualization. Based on this experimental phase, BC/AC = 10% was chosen to manufacture the modified HMA. Resistance parameters under monotonic loading (stability—S, flow—F, S/F ratio of the Marshall test, and indirect tensile strength in dry—ITSD and wet—ITSC conditions) and cyclic loading (resilient modulus, permanent deformation, and fatigue resistance under stress-controlled conditions) were evaluated on the control HMA (AC unmodified) and the modified HMA. Additionally, the tensile strength ratio (TSR) was calculated to evaluate the resistance to moisture damage. Abrasion and raveling resistance were evaluated by performing Cantabro tests. BC-OPMF is shown to be a sustainable and promising material for modifying asphalt binders for those seeking to increase stiffness and rutting resistance in high-temperature climates, resistance to moisture damage, raveling, and fatigue without increasing the optimum asphalt binder content (OAC), changing the volumetric composition of the HMA or increasing the manufacturing and construction temperatures.

The primary aim of this study is to evaluate the impact of incorporating crumb rubber (CR) and styrene-butadiene rubber (SBR) additives, ranging from 0% to 5% by weight of bitumen, on the performance of a bituminous concrete mixture using the wet process. Laboratory experiments, including the Marshall test, were conducted to establish the optimum bitumen content (OBC) for the hot mix. The study focuses on determining the optimal proportions of CR and SBR to achieve maximum strength. The results show that increasing the proportions of both CR and SBR leads to significant improvements in strength, with the maximum stability recorded at 16.14 kN and a flow of 1.23 mm for a mix containing 5% CR and 4% SBR. The findings further suggest an inverse relationship between CR content and strength, while an increasing SBR content enhances strength. Consequently, the optimal proportions for incorporating CR and SBR additives are identified as 5% and 4%, respectively.

Mineral fillers are known to affect the cracking properties of hot mix asphalt (HMA) significantly. Therefore, the aim of the study was to investigate the effects of filler concentration on the indirect tensile cracking indices of hot mix asphalt at an intermediate temperature. To make the test samples, the standard 100% limestone filler was substituted with the recycled fillers of hollow concrete block (HCB) powder and brick powder (BP), in three different concentrations (3%, 5%, and 7%). Optimal concentration levels resulted in superior mixes that could sustain pavement service life and environmental friendliness. Mixtures with 100 and 150 mm-diameter specimens were evaluated using the flexibility index (FI), crack tolerance index (CT index), fracture energy index (FEI), toughness index (TI), cracking resistance index (CRI), and fracture strain tolerance (FST) index from IDT test. The results indicate that filler concentrations influence the IDT indices significantly and that the 5% filler mixtures yielded reasonable testing results. The two specimen sizes were found to have moderate to strong correlation coefficient (R2) values for the same indices, supporting that both may be used interchangeably to assess cracking resistance in HMA. Thus, using 100 mm-diameter specimens may be used to minimise costs and material quantities. [ABSTRACT FROM AUTHOR]

Different types of additives are used in asphalt modification to enhance several properties within the asphalt pavement. In various cases, modification is needed by using multiple additives, which is called composite modification. In this study, glass fibre and nano clay were used to modify the asphalt pavement. The amount of these two additives, together with the optimum bitumen content, was determined by the response surface methodology (RSM). Central composite method (CCD) was used for determining the optimum amount of independent variables (nano clay, glass fibre, bitumen content), by evaluating the dependent variables. Marshall mixture design criteria and minimum bitumen content, were the optimal conditions. As a result, the mixture containing 0.2% glass fibre, 3.693% nano clay and 4.096% bitumen content, was predicted to give the most desirable characteristics. Additionally, verification tests were conducted to evaluate the adequacy of the predicted model. The results were within the 95% confidence intervals for all response variables, which demonstrates the validity of the model obtained in the study. Consequently, CCD can be used to obtain design optimisation of asphalt modification with less mixture production for experimental stages. This is a substantial advantage, which supports human safety and environment- friendly practices. [ABSTRACT FROM AUTHOR]

In this study, the engineering properties of basalt aggregate used for asphalt road pavement on Jeju Island were evaluated, and the characteristics of the asphalt mixtures used were evaluated to assess the suitability of Jeju Island basalt as road construction material. Chemical composition and surface morphology analysis of the basalt and granite aggregate, engineering characteristics analysis, and filler property evaluation were performed. Mix design was performed, and the basic properties of three asphalt mixtures for the surface, intermediate, and base layers were evaluated. Permanent deformation resistance was evaluated through a wheel tracking test, and moisture resistance was evaluated through a dynamic immersion test and a tensile strength ratio test. The optimum asphalt contents of the asphalt mixture using low-porosity basalt aggregate and high-porosity basalt aggregate were determined to be 5.7% and 5.9% in the surface layer, 5.3% and 5.4% in the intermediate layer, and 4.7% and 5.1% in the base layer, respectively. It was found that the basic properties of the asphalt mixtures satisfied Korean quality standards. The dynamic immersion test results of low-porosity basalt aggregate and high-porosity basalt aggregate were 20% and 10%, respectively, which fall far below the quality standard of 50%. The tensile strength ratios of the basalt asphalt mixtures for the intermediate layer were 0.69 and 0.40, and they were found to increase significantly to 0.87 and 0.80 after the application of a suitable anti-stripping agent. Therefore, it was concluded that in order to apply Jeju Island basalt to asphalt pavement, an appropriate anti-stripping material must be applied. [ABSTRACT FROM AUTHOR]