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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]

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]

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]

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]

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]

Plastic asphalt mixtures (PAM) have attracted extensive attention lately; however, their application in the field has not been so common because of the lack of clear understanding of the behavior of the asphalt mix after modification. In the interest of closing this gap, a modeling tool able to estimate the plastic effect on asphalt mixtures properties is needed. Nevertheless, the suggestion of a generalized model is complex due to the numerous variables involved. To facilitate this process, the present article aims to expand the current knowledge about PAM modeling by providing a clearer understanding of what variables have the highest impact on PAM properties. To do so, data from previous articles have been gathered and machine learning and shapley additive explanation values have been applied. PAM properties assessed were air voids, Marshall stability, Marshall flow, indirect tensile strength, and tensile strength ratio. Overall, the features with the highest impact are plastic type and content (35%), aggregates gradation (35%), aggregates absorption (9%), bitumen content (8%), mixing technique (4%), and bitumen penetration (3%). The final proposed models extend the application of previous machine learning models and feature importance understanding, and, in the field, they can serve as an initial estimate of the plastic effect on different asphalt mixture types. It is suggested that future articles intending to model PAM should consider these critical features during model formulation, and articles evaluating new types of PAM should clearly report these properties, for they might be the basis of these generalized future models. [ABSTRACT FROM AUTHOR]

Weigh-in-motion (WIM) systems are essential for efficient transportation and monitoring parameters such as vehicle number, speed, and weight to ensure regulatory compliance and enhance road safety. Recently, WIM measurements using the Glass Fiber Reinforced Polymer Fiber Bragg Grating (GFRP-FBG) sensors have shown robustness and effectiveness. However, the accuracy of weight evaluation using the WIM systems based on GFRP-FBG sensors can be significantly influenced by the vehicle-wandering effect, which introduces uncertainties in wheel position determination and weight calculations. This paper assessed the impact of vehicle wandering on the accuracy of a WIM measurement system based on GFRP-FBG sensors by utilizing a new hybrid sensor-camera system that integrates roadside cameras and in-pavement GFRP-FBG sensors. The detailed methodology and framework of the developed hybrid system are introduced, followed by field testing on Highway I-94 in the United States. The field testing results indicate that by using the hybrid system, the wheel load detection accuracy of the WIM system based on GFRP-FBG sensors can be controlled to be a Type I or Type III WIM according to the ASTM 1318E-09 standard, with an average accuracy ranging from 87.83% to 94.65%. At the same time, when the wander distance is less than or equal to 9 cm, the developed WIM system proves to be very cost-effective as it only comprises two GFRP-FBG sensors, one temperature FBG sensor, and one camera. These findings indicate the practical potential to enhance the accuracy of WIM systems based on GFRP-FBG sensors designed for highways for low-coast, reliable, and accurate measurements by addressing vehicle wandering effects. [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]

Pavement preservation treatments applied before significant deterioration and cracking has occurred can extend the service life of a pavement and reduce future maintenance costs. Rejuvenating materials can help to increase the performance of these preservation treatments. Soybean derived additives have been found to greatly reduce the stiffness of aged and brittle asphalt binders. This study proposes the use of these bio-based additives to be used in a fog seal emulsion and as a bio-cutback treatment. The use of functionalized soybean oil in asphalt pavement treatments can greatly reduce the environmental concerns related to other petroleum-derived materials while providing an economical benefit to local agriculture economy. A small field study was conducted to measure the effectiveness of these biomaterials. No significant effect was observed in the extracted asphalt properties, or the low-temperature fracture energy measured by disk-shaped compact tension test (DCT); however, a decrease in the dynamic modulus at higher frequencies and a large decrease in permeability was observed. The treatments were successful in sealing the asphalt pavement, but a higher application rate is needed to show more significant differences in the rheology. [ABSTRACT FROM AUTHOR]

Shingle material can appear as an excess usage due to defective production problems or at the end of their service life. Especially the reuse of shingle materials in bitumen has brought a different approach in terms of sustainability. In this study, the utilization of production shingle waste material in asphalt pavement were investigated. Mechanical properties of hot mix and warm mix asphalt samples involving different amount of production shingle waste (1-6% by weight of the aggregate) were evaluated. Following the determination of optimum rate of shingle waste bitumen content is reduced to decrease both hazardous effects of bitumen and production cost. Marshall Mix Design criteria was employed on determination of maximum reduction on bitumen content and the amount of shingle utilization within the asphalt pavement. As a final analysis, indirect tensile tests were performed on the specimens prepared with determined bitumen content and shingle waste. As a result, it is concluded that, utilization of waste shingles within the asphalt mixture not only benefits the environment and cost but also improves Marshall stability and Marshall quotient of the mixtures. [ABSTRACT FROM AUTHOR]

This study investigated the effects of using lime of three different origins in the mixture in specific proportions instead of fillers in hot mix asphalts. The performance changes of the mixture were investigated when three different hydrated powdered limes produced from the quarries in the Kavak district of Samsun were used as fillers to varying rates in the hot asphalt mixtures. In the study, hot mix asphalt samples were prepared by reducing the amount of filler in the mixture by 0.5%, 1%, 1.5%, and 2%, as well as lime-free samples, by adding lime of three different origins, which were supplied in the same amount. Then, the same sample group was reproduced and conditioned according to the AASHTO T 283 standard to compare and investigate the effects of water damage on the performance of the hot mix asphalt. The results of both groups of samples were compared according to Marshall stability and flow values. In the analyses made, it has been determined that the sum of CaO and MgO is greater than the 90% threshold recommended in the Highways Technical Specification (HTS), and the SO3 is less than the 2% threshold recommended in the HTS are effective in increasing the pavement performance in both cases. [ABSTRACT FROM AUTHOR]

This research deals with mechanical tests and structural analyses of a pre-designed asphalt pavement, considering scenarios in which the wearing course is unreinforced or reinforced with geogrid. The experimental program included the design of two hot mix asphalts. Reinforced specimens were produced with three different types of paving geogrids. Mechanical tests of tensile strength and resilient modulus were carried out, as well as structural analyses of the pre-designed pavement, varying the resilient stiffness of the wearing course. It provided the maximum horizontal tensile stresses and strains that were used to evaluate the fatigue response of the reinforced and unreinforced asphalt pavements, according to different fatigue models. The results of the mechanical tests showed that the reinforced mixtures presented higher values of tensile strength and resilient modulus than unreinforced asphalt mixtures. Regarding the effects of reinforcement geogrids on the structural performance of the asphalt pavements, the results indicated that despite the tendency for higher maximum horizontal tensile stresses in lower fibers, the wearing course of asphalt mixtures with geogrids exhibited a reduction in specific tensile strains. Consequently, a tendency for longer fatigue life was verified. In addition to conventional reinforcement mechanisms, the pre-stressing or pre-tensioning of the geogrid due to compaction is also assumed to account for the superior structural performance of reinforced asphalt mixtures. The mechanical properties of the reinforced asphalt mixes and their corresponding structural pavement responses were found to be dependent on the type of geogrid, the grading zone of aggregate and the binder contents of the asphalt mix that composes the wearing course. [ABSTRACT FROM AUTHOR]

Guayule resin was investigated through mixture to assess its role in the field performance. For performance comparisons, conventional asphalt, neat guayule, asphalt–rubber–guayule, and guayule–rubber binders were implied. Field-simulated lab mixtures were made to investigate the major distresses. Modified Lottman, rut, semicircular bending, and disk-shaped compact tension tests were used to assess stripping, rutting, fatigue, and thermal cracking resistances. Stripping and rutting susceptibilities were also assessed by Hamburg wheel-tracking test. The outcomes disclosed that when the modified Lottman test was used, guayule containing a 7% air content was more susceptible to stripping than that containing a 3.5% air content, resulting in tensile strength ratios of 40% and 71%, respectively. All investigated mixtures did not reach out the stripping inflection point under the Hamburg wheel-tracking criteria. Asphalt offered the worst Hamburg rut depth, which was 3.2 mm after 20,000 passes. Guayule-based mixtures perfectly resisted rutting as proven by the rut test. Guayule offered the worst rut depth of 6.3 mm, indicating a great rutting resistance. The guayule-based mixture had a high fracture toughness at intermediate temperatures. Guayule and guayule–rubber mixtures offered a critical strain energy release rate of 0.65–0.69 kJ/m2 compared to 0.46 kJ/m2 for asphalt. They, however, tended to possess low thermal fracture resistance (less than the threshold fracture energy, 400 J/m2). Conversely, a blend of 62.5% asphalt, 12.5% rubber, and 25% guayule offered 591 J/m2 at its performance grade low temperature (−16°C) and 409 J/m2 at −22°C compared to 429 J/m2 for asphalt at the later temperature, which represented the performance-grade low temperature of asphalt. [ABSTRACT FROM AUTHOR]

In the laboratory, the density of pavement cores (cylindrical samples of hot mix asphalt (HMA) material taken from roads) is assessed using an electromagnetic (EM) bench consisting of two ultra-wideband (UWB) Vivaldi antennas and a vector network analyser (VNA). The main objective is to replace the nuclear gauge system currently used in the laboratory as the standard method for this purpose. Firstly, specific antipodal Vivaldi antennas have been adapted from the literature. Their dimensions are 7 × 7 cm with a bandwidth [1.5–15 GHz]. Secondly, a tomographic approach is compared with an analytical solution and a Finite-Difference Time Domain (FDTD) simulation, based on a time-domain estimation of the dielectric under test (DUT) with a single transmitter/receiver configuration. A laboratory validation is presented and the adapted antennas as well as the time domain approach show acceptable results for assessing the dielectric constant on known materials. Finally, to show that the proposed EM bench is a promising non-ionizing solution, the density or equivalent compactness of HMA cylindrical samples is estimated and compared with nuclear gauge results. [Display omitted] • A new electromagnetic device evaluates the density of bituminous road materials. • The EM bench is composed of Exponential Tappered Slot Antennas and a Vectorial Network Analyser. • Measurements, simulation and theoretical equations have been compared to validate the approach in the time domain. • Density assessment is carried out on HMA samples and comparisons are made with nuclear gauge results. • The proposed approach is an alternative to nuclear gauge and promises numerous applications. [ABSTRACT FROM AUTHOR]

Adhesiveness is a property that directly affects the service life of asphalt pavements. Over the years, different materials, research methods and tests have been used to investigate different adhesiveness aspects of materials. This paper investigated two asphalt binders, one with and one without amine-based anti-stripping agent, as well as two aggregate sources. The objective was to investigate the effects of rheology (stiffness and rutting) of the asphalt binder and adhesiveness of asphalt binders to different substrates on the resistance to moisture conditioning. The results indicated that moisture conditioning reduced the average stiffness of the binders by about 15% for both binders. The addition of amine-based anti-stripping agent reduced the stiffness of the neat binder by approximately 9%, and at 82°C the neat binder presented higher rutting resistance if compared to the modified binder using anti-stripping agent. The aggregate area within the HMAs in contact with asphalt binder did not show a good correlation with the pull-off tensile strength in the dry condition, but it presented good correlation after moisture conditioning. This suggests that adhesion force itself may not be greatly affected by the proper contact between aggregate and binder, but such contact does help preventing moisture damage in the interface. [ABSTRACT FROM AUTHOR]

This research effort is geared towards revealing the latent potential of discarded shoe polish that might be repurposed as an asphalt fluxing agent for the construction of durable and sustainable road surfaces. To drive this creative invention, the effect of various proportions of waste shoe polish (e.g., 5, 10 and 15 wt. % WSP) on the performance of base AP-5 bitumen was inspected in great detail. A meticulous investigation of the chemical, physical, and rheological properties of the resultant combinations was carried out using a variety of state-of-the-art laboratory techniques, specifically: thin-layer chromatography-flame ionization detection (TLC-FID), Fourier transform-infrared spectroscopy (FT-IR), needle penetration, ring-and-ball softening point, Brookfield viscometer, ductility, flash/fire points, dynamic shear rheometer (DSR), multiple stress-creep recovery (MSCR), and bending beam rheometer (BBR) tests. The Iatroscan data disclosed that the continuous feeding of binder with WSP had a minor impact on SARA fractional distribution, regardless of aging. According to the FT-IR scan, the stepwise addition of WSP to the binder did not result in any significant chemical alterations in the blends. The combined outcomes of the DSR/BBR/empirical test methods forecasted that the partly bio-sourced additive would greatly improve the mixing–compaction temperatures, workability, and coating–adhesion properties of bituminous mixtures while imparting them with outstanding anti-aging/cracking attributes. In short, the utilization of waste shoe polish as a fluxing agent for hot asphalt mix production and application is not only safe, feasible, and affordable, but it has the potential to abate the pollution caused by the shoe-care market while simultaneously enhancing the overall performance of the pavement and extending its service lifespan. [ABSTRACT FROM AUTHOR]

To enhance the moisture damage performance of hot mix asphalt (HMA), treating the aggregate surface with a suitable additive was a more convenient approach. In this research, two types of aggregate modifiers were used to study the effect of moisture damage on HMA. Three different aggregate sources were selected based on their abundance of use in HMA. To study the impact of these aggregate modifiers on moisture susceptibility of HMA, the indirect tensile strength test and indirect tensile modulus test were used as the performance tests. Moisture conditioning of specimens was carried out to simulate the effect of moisture on HMA. The prepared samples' tensile strength ratio (TSR) and stiffness modulus (Sm) results indicated a decrease in the strength of the HMA after moisture conditioning. After treating the aggregate surface with additives, an improvement was seen in dry and wet strength and stiffness. Moreover, an increasing trend was observed for both additives. The correlation between TSR and strength loss reveals a strong correlation (R2 = 0.7219). Also, the two additives indicate increased wettability of asphalt binder over aggregate, thus improving the adhesion between aggregate and asphalt binder. [ABSTRACT FROM AUTHOR]

In this study, the damage caused by solutions with different salt contents, which are actively used in combating snow and ice in winter climate conditions, on asphalt concrete roads in different periods was investigated experimentally. Hot mix asphalt concrete (HMA) prepared within the framework of the standards for the wear layer directly affected by snow and ice were subjected to freeze-thaw at different periods (7, 14, 21, 28 cycles) and two different thawing environments were prepared for each thaw. For this reason, two different sodium chloride (NaCl) solutions, 1 mol (M) and 4 mol (M), were prepared and the frozen HMA samples were thawed in 1M or 4M solution environments at the end of each cycle. Thus, the effects of salt on the damage to the HMA surface were investigated. While the Marshall Stability (MS) value of the reference sample that was not exposed to freezing and thawing was 985 kg, the MS values of the samples exposed to freezing and thawing cycles for 7, 14, 21 and 28 days in 1M solutions were found to be 971 kg, 938.5 kg, 889.5 kg and 910 kg, respectively. On the other hand, the MS values of the samples exposed to freezing and thawing cycles for 7, 14, 21 and 28 days in 4M solution were obtained as 914 kg, 814 kg, 790 kg and 765 kg, respectively. In this study, it was observed that the freeze-thaw cycle caused a decrease in the stability of asphalt concrete. [ABSTRACT FROM AUTHOR]

The research focuses on the assessment of the potential use of microwave radiation as alternative heating method for reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) production. Recent studies on the use of microwave radiation in road engineering mostly focused on the cracked asphalt pavement. In the study, microwave heating performance was assessed based on the physical and mechanical characteristics of HMA with different RAP contents containing various amount of moisture. Results were compared to the HMA consisting of high amount of RAP containing Styrene–Butadiene–Styrene (SBS) polymer modified binder. The test results confirmed the possibility of microwaves utilization in order to heat the HMA without adversely affecting its basic properties. The research also shows the possibility of heating RAP in the process of HMA production, especially if the RAP moisture level is above 3%. In addition, the tests on HMA did not reveal any negative impact of microwave heating in the case of using wet RAP for the production of HMA. The susceptibility of the SBS polymer to microwave radiation was indicated by comparing the behavior of the two HMA types under its influence. HMA containing modified bitumen appears to achieve higher temperatures than HMA with unmodified bitumen after the same time of microwave heating. [ABSTRACT FROM AUTHOR]

Hot mix asphalts are known to have a self-healing property and microcracks in the pavement can close to some extent after they occur if they are not subjected to load and if sufficient time is allowed. However, this healing period is prolonged, and the healing rate is not very high. In this study, calcium alginate capsules containing waste vegetable oil and waste mineral oil as rejuvenating agents were produced, and used in asphalt mixtures at four different rates (0.25%, 0.50%, 0.75%, and 1.0%) by weight. The study aims to develop an environmentally friendly and economically viable repair method by using waste oils. Marshall stability and flow and tensile strength ratio tests were conducted on cylindrical specimens. Additionally, three-point bending test was performed on aged asphalt mixtures to determine the self-healing rates of cracks formed in the specimens. Fourier transform infrared spectroscopy was conducted on bitumen specimens taken before crack formation and after the healing period to determine the percentage of ruptured capsules in the mixture. The results showed that the addition of capsules containing waste mineral oil and vegetable oil reduced stability values and increased flow values. However, according to the results of the retained Marshall stability test, it was determined that the addition of capsules, especially at a 0.5% ratio, increased resistance to moisture damage. Regarding crack-healing results, it was found that temperature and curing time increased healing rates, and capsules containing waste mineral oil provided higher healing rates compared to those containing waste vegetable oil. [ABSTRACT FROM AUTHOR]

The recyclability of waste cooking oil (WCO) as rejuvenator for aged asphalt mixture improved the serviceability of pavement itself. Currently, the researcher is exploring the new potential of WCO as modifier for binder modification. However, the issue of compatibility properties in the modification of binder with WCO arises since the poor mechanical performance of asphalt mixture is globally recorded thus reflected the weakness of adhesion bonding inside the pavement material. Basically, the superior mechanical performance of asphaltic concrete exhibited good adhesion bonding between binder-aggregates interaction in bituminous mixture. In fact, the potential of high adhesiveness binding properties is affected by the chemical theory which is mostly related to the polarity factor. Therefore, it is vital to conduct the chemical analysis and microstructure observation to obtain a comprehensive understanding of the polar group behaviour for the internal structure in pavement material that influencing the adhesion performance for the structural arrangement material in the mixture. Therefore, excellent adhesion is capable of improving mechanical performance of Hot Mix Asphalt (HMA). The identification of chemical composition for polarity group determination was identified by using Gas Chromatography-Mass Spectrometry (GC-MS). Meanwhile, the adhesiveness measurement between binder-aggregate interactions in the mixture was observed with Field Emission Scanning Electron Microscope (FESEM) which physically resulting in mechanical performance by conducting resilient modulus test, dynamic creep test and indirect tensile strength (ITS) test. Results showed that the incompatibility characteristic is revealed between untreated WCO and conventional binder (PEN 60/70) based on the identification of polar and non-polar compounds interaction. Thereby, exhibits the existence of gap and void structure arrangement in HMA through FESEM visualization hence affecting the poor mechanical strength of asphalt mixture. [ABSTRACT FROM AUTHOR]

One environmental problem in most countries is the huge quantities of plastic waste, which has different types of polymers such as polyethylene terephthalate (PET), polypropylene (PP)., These plastics become a problem because of their non-biodegradability, toxicity, etc. The recovery of plastic waste in pavements has become an ecological technique that contributes to the preservation of natural resources. In this study, PET waste was used as an additive for hot mix asphalt at two sizes (2.50 to 1.25 mm, and 0.315 to 0.160 mm) and three contents (3%, 5%, and 7% by weight of binder), PET modified mixes creep-recovery behavior was tested by four points bending test and compared with control mix (without PET waste) at three different temperatures (0°, 25° and 50°C), were added directly to the mixture as the method of dry process. The results showed that the addition of PET waste yields better results that which could increase the asphalt bituminous resistance against permanent deformation and a clear rigidity improvement in the various temperature because it's more thermally stable and can limit the degradation risks of the bituminous mixtures compared to the control mixture. Further, can be prepared an eco-friendly road construction with less material cost. [ABSTRACT FROM AUTHOR]

Reducing lab work to save time and costs has become one of the challenges which need to be taken on by researchers, for this reason, and a lot of studies have been performed to achieve this aim. Many approaches were developed for developing these models such as statistical, mathematical, mechanistic and so on. In the last decades, an advanced approach simulating the human neural system has opened the door for researchers to do what other approaches have failed with. One of these advanced approaches is called artificial neural networks (ANN) as one of so-called artificial intelligence (AI). The purpose of this study is to introduce ANN as a design tool for hot mix asphalt (HMA) based on actual data for job mix formula; achieving these points will contribute to reducing the time, cost, and data in the design of hot mixes asphalt. Data of 252 mixes were collected from different highway agencies in Iraq, all these mixes were designed according to the Marshall method. The data of 170 mixes were used for developing the ANN model, while the data of 82 mixes were discarded due to the shortage of information. Ten parameters (penetration, kinematic viscosity, surface area of aggregate, mechanical abrasion, and binder content) were extracted from the data of 170 mixes to be used as input and outputs variables for training the ANN. The results showed the visibility of ANN as a tool for designing the HMA as shown from the high correlation and quality analysis. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to compare and analyze the anti-aging durability of asphalt and asphalt mixture under the conditions of inherent and improved performance. The research contents include: the mechanical properties (dynamic stability, bending strain, freeze-thaw splitting tensile strength ratio (TSR)) of different modified asphalt mixtures were tested by using the best modified asphalt. Design/methodology/approach: The anti-aging durability of different modified asphalt was analyzed by using the results of macro tests such as penetration and softening point as evaluation indexes. Meanwhile, the change of the asphalt colloid instability index (Ic) in the aging process was used as the evaluation index to verify the results of the macroscopic test, and the best modified asphalt was obtained. On this basis, the composition of different modified asphalt mixtures was designed by using the best modified asphalt. Meanwhile, water stability was used as evaluation indexes to study the anti-aging durability of different modified asphalt mixtures. Findings: The results show that styrene-butadiene-styrene (SBS) modified asphalt has better aging resistance. Due to the special storage time, the performance of rubber asphalt is also the best. Meanwhile, in terms of modified asphalt mixture, its high temperature performance and durability of anti-aging is as follows: 4% SBS /16% rubber modified asphalt mixture (IV) > 4% SBS modified asphalt mixture (II) > asphalt mixture (90#) (I) > 16% rubber modified asphalt mixture (III). The low temperature performance and durability of anti-aging is as follows: Ⅱ > IV > Ⅰ > Ⅲ. The water stability performance and durability of anti-aging is as follows: IV > Ⅲ > Ⅱ > Ⅰ. Originality/value: The research results have important theoretical and guiding significance for exploring the change of intrinsic properties and improved properties of asphalt and asphalt mixture in the aging process and revealing the anti-aging mechanism of different modified asphalt mixtures. [ABSTRACT FROM AUTHOR]

The incorporation of Reclaimed Asphalt Pavement (RAP) in the recycling process of asphalt pavement can save both the environment and money. This study was conducted to investigate the use of nanomodified asphalt binder in the recycling of RAP material to increase the incorporation of RAP percentage in recycled asphalt compared to using neat (unmodified) asphalt binder. For this evaluation, a nanoclay modified and unmodified binder was used. The RAP (aged) binder was prepared by putting the unmodified binder in the Rolling Thin Film Oven (RTFO) and two cycles of Pressure Aging Vessel (PAV). Then, the rutting, fatigue, and low-temperature performance of recycled binders with different percentages of RAP during the aging of the binder were evaluate by performing Bending Beam Rheometer (BBR) at low temperature and Dynamic Shear Rheometer (DSR) at high-temperature and medium temperatures. The results demonstrated that the maximum use of 20% RAP binder (33% RAP material) was allowed in the recycled pavement using nanomodified binder. While the maximum use of 10% RAP binder (17 % RAP material) was allowed with the unmodified binder. This increase in the incorporation of RAP percentage in recycled asphalt pavement can pave the path to industrialize the use of the nanomodified binder in the recycling of asphalt pavement and its usage in severe weather conditions. [ABSTRACT FROM AUTHOR]

The implementation of warm mix asphalt and chemical compaction aids is becoming more widespread. A growing number of contractors are using warm mix asphalt technologies to reduce mixing and compaction temperatures, reduce fuel consumption, improve compatibility, and increase economic and environmental value. In 2009, three pavement overlay projects were constructed in the state of Iowa using both hot mix aphalt and warm mix asphalt mixes to compare their performance. A series of dynamic modulus tests were conducted using field and laboratory mixtures of hot mix asphalt and warm mix asphalt. For each project, twelve specimens, including six hot mix asphalt specimens and six warm mix asphalt specimens, were tested to determine dynamic modulus and phase angles. These results were used as input parameters for designing each pavement in the mechanistic-empirical pavement design guide (MEPDG) and in finite element viscoelastic simulations to predict the performance behavior of warm mix asphalt and hot mix asphalt. A step-by-step framework to convert dynamic modulus results to Prony series to use in finite element simulation models was developed and is detailed for one mixture. This research compared predicted rutting damage by MEPDG design, estimated rutting from finite element simulations, and measured rutting in the field. The results show that MEPDG based on linear elastic theories may overestimate the rutting of pavements while the finite element based on viscoelastic theory accurately predicted the rutting of pavements. Therefore, a series of proposed calibration coefficients from this research can be useful for industrial applications and design engineers to modify and correct MEPDG overlay design thicknesses on top of hot mix asphalt, and jointed plain concrete pavement surfaces with either hot mix asphalt and warm mix asphalt mixtures. [ABSTRACT FROM AUTHOR]

During the fabrication of new products, a variety of wastes discharged and stored by causing harsh environmental problems. The marble processing plant is amongst the industrial sector that produces huge waste. Thus, the main purpose of this study is to evaluate the combined effects of marble waste dust filler and Superpave aggregate gradation on the performance of HMA. Based on the Marshall Mix design, seventy-two (72) specimens were produced from three below-restricted zone (BRZ) of Superpave gradation (BRZ4, BRZ5, & BRZ6) by using the 0.45 power chart. The design gradation obtained to be BRZ5 with 4.96% OBC with corresponding values 9.13 KN of stability, 2.96 mm of flow, 73.51% of VFA, 15.73% of VMA, 2.308 gm/cm3, of bulk density and 4% of air void. The crushed stone dust filler was partially replaced by Marble Waste Dust filler (under No. 200 sieve) at replacement rate of (1%, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5%) by keeping design gradation and OBC constant. The test showed satisfactory results. The Marshall mix design parameters of all mixtures are within specification limit under international and local specifications. Marble waste dust filler when blended with a BRZ of Superpave gradation indicated a substantial effect on Marshall stability with 10.18 KN value at 3% MWD filler content. [ABSTRACT FROM AUTHOR]

In this study, it has been attempted to use thermodynamics theories and the surface free energy (SFE) method to evaluate the effect of anti-stripping additives on the asphalt binder cohesion and asphalt binder–aggregate adhesion under dry and wet conditions. Two types of aggregate, granite and limestone, AC 60–70 and two additives (a polar copolymer and an ethylene copolymer with mineral asphalt binder) used are among the materials used in this study. The results indicate that the use of both types of polymer has increased the cohesion of the asphalt binder and reduced failure in the asphalt binder film. The results show that the polar copolymer increases the basic components and decreases acidic component of the asphalt binder surface free energy that increases the adhesion with acidic aggregates that are susceptible to moisture-induced damage. Ethylene copolymer material also increased the asphalt binder surface free energy that strengthens the non-polar asphalt binder–aggregate bonds. Both polymer materials have reduced the separated free energy and increased the adhesion free energy that reduces the desire for the stripping process in the asphalt mixture. The results of mechanical tests also show that the use of polymeric additives has improved the asphalt mixtures strength against moisture-induced damage. [ABSTRACT FROM AUTHOR]

Warm mix asphalt is gaining increasing acceptance in pavement construction due to their advantages in energy saving, reduced emissions and improved worker comfort. This paper highlights another benefit of warm mix asphalt (WMA) in allowing shorter road closure time window for pavement repair or resurfacing works as compared with the conventional hot mix asphalt (HMA) construction. This is of good practical value to busy roads where closure time windows as short as 4–5 h are common. A finite-element simulation model for predicting temperature cooling of WMA and HMA was developed to study the potential benefits of WMA in allowing shorter time windows for pavement repairs and resurfacing operations. Full-scale field trials were conducted to compare the temperature cooling characteristics of multi-lift construction of WMA and HMA, and provide the necessary data to calibrate and validate the simulation model developed. The validated simulation model was employed to analyse the cooling characteristics of HMA and WMA resurfacings under different environmental conditions and resurfaced layer thicknesses. These analyses provide useful information on the length of cooling time needed before the resurfaced layer is sufficiently stable to receive traffic. It was found that, compared with HMA, the use of WMA shortened the night-time cooling time needed by 5–35 min when the resurfacing thickness increased from 75 to 150 mm. The corresponding cooling time reductions for day-time paving were 19–79 min. [ABSTRACT FROM AUTHOR]

The continuing rapid growth in traffic, along with the rise in allowable axle loads, requires improvement of highway paving materials. In the recent decades, different types of fiber materials are utilized for improving the performance of asphalt mixture. A laboratory investigation was carried out into the effect of adding Glass Fiber (GF) on some properties of Hot Mix Asphalt (HMA) mixtures. Subsequently, five HMA specimens were prepared using the Marshall mix design method for wearing surface mix (mix 4C). Marshall Stability (MS) and flow tests were applied to the specimens. Also, MS and flow values were recorded. For the Optimum Asphalt Content (O.A.C) and different GF percentages, the Marshall parameters were calculated. Then, some special tests were conducted to measure the different mix properties, including loss of stability, wheel tracking and indirect tensile strength tests. Results of the study led to important conclusions regarding using of Glass Fiber (GF) to improve most of the properties of HMA mixtures. Finally, this study recommended a proposed mix with 0.25% GF by weight of the total mix. [ABSTRACT FROM AUTHOR]

The endurance limit of the bituminous mix is an important parameter in the mechanistic-empirical based pavement design concept. Dense bituminous macadam (DBM) is one of the most used bituminous mixes in the binder course of pavement construction. This research aims to evaluate the fatigue endurance limit of the dense bituminous mix using beam fatigue tests. In the beam fatigue test, samples, composed of DBM gradation type II and Polymer modified bitumen of grade 40 (PMB-40) binder, were tested under strain conditions: 600 µe, 400 µe, 300 µe, 200 µe. Further, the number of repetitions until failure was estimated using logarithmic regression and single-stage Weibull function method for those which did not fail after 10 million cycles. The endurance limit was determined from the analysis of the graph plotted between strain values and the number of repetitions/cycles until failure. The logarithmic regression method showed better results for fatigue life, compared to the single-stage Weibull method. The mixture of DBM-II graded aggregates and PMB-40 binders could be used in the pavement construction for longer design life. Finally, the laboratory determined Endurance limit is used in pavement design and is presented through a representative case. [ABSTRACT FROM AUTHOR]

Electric arc furnace (EAF) aggregates, by-products of the homonymous steelmaking process, represent an ideal solution for asphalt mixtures, above all for wearing courses where skid resistance and durability are essential functional requirements. Their use, which is subordinate to the compliance of chemical specifications, finds some practical interest limits mainly related to transportation (extremely high bulk specific gravity) and placement (unsatisfactory compaction) operations. Thus, the aim of this experimental study was to determine an ideal artificial to natural aggregates replacement rate, also identifying the most suitable particle size range, for dense-graded asphalt wearing courses. The results highlighted how the best balance between compaction and mechanical performances was registered by a mix which was formulated considering a partial replacement of 54% (v/v%), distributed only in the coarsest fraction. The introduction of limestone as "excipient" in the coarse-fine and finer size ranges reduces the weight of the mixture, guaranteeing at the same time an optimum compaction degree, high levels of stiffness in the viscous-elastic region and Marshall stability and extended fatigue life. [ABSTRACT FROM AUTHOR]

Previous work with Isosorbide Distillation Bottoms (IDB), and other isosorbide and soybean derived materials as additives in polymer-modified warm mix asphalt (WMA) showed that said materials were shown to behave like antistrips in the Hamburg Wheel Tracking Device (HWTD) test when used a dosage of 0.75% by weight of the binder. Because of this evidence, there is an interest in how specimens produced with newly developed isosorbide and soybean bio-derived chemical additives would affect the compaction and dynamic modulus performance of specimens produced at two compaction temperatures (120°C – WMA and 140°C – hot mix asphalt (HMA)) as compared to a control and commercial additives derived from tall oil. There were no statistical differences observed between the additives and the control due to high variability in results for compaction performance, while for dynamic modulus performance only the additive Epoxidized Benzyl Soyate (EBS) performed significantly different from the control and other additives at both compaction temperatures. Only three of the newly developed additives could be identified as WMA additives: Crude Isosorbide (CI), Reactor Product (RP) and Epoxidized Soybean Oil (ESO) based on the number of gyrations and dynamic modulus performance compared to the control group at both compaction temperatures. [ABSTRACT FROM AUTHOR]

The predicted performance and service life of the pavement depend largely on the properties of bitumen used in the mixtures. The most important feature of bitumen, which has profound effect on the performance of the road is durability. The durability of bitumen is expressed as the resistance to aging. In this study, the bituminous mixture aging was performed instead of bitumen aging in order to represent the aging in the field in the best possible way. The aim of this paper is to evaluate different proposed laboratory aging methods (NCHRP 09-52, NCHRP 09-54 and RILEM) in relation with the current Standard AASHTO R30 (Standard Practice For Mixture Conditioning of Hot Mix Asphalt standard) and to make comparison with the samples performance taken from the field in terms of Indirect Tensile Strength (ITS). The level of aging has also been compared with the samples taken from recently constructed pavement surface and from the five years old pavement surface. Results depicted that, laboratory aging methods revealed the field aging properties on the unaged bitumen. Based on the results, 2 hours forced draft oven aging at 135°C is recommended as short term aging condition because, 2 hours or 4 hours short term forced draft oven aging did not yield significant variation in terms of ITS values. Additionally, 120 hours (5 days) oven aging of compacted samples at 85°C can be recommended as long term aging condition. [ABSTRACT FROM AUTHOR]

Moisture damage in asphalt mixtures can be defined as the loss of durability and strength caused by the effect of moisture. In order to improve the strength of asphalt mixtures against this damage, anti-stripping additives are used to increase the aggregate-asphalt binder adhesion and cohesion. In this study, the influence of Polybutylene on the moisture susceptibility of asphalt mixtures is investigated. To evaluate the effects of anti-stripping additives on the specimens made with granite and limestone aggregates, the indirect tensile strength ratio test and the theoretical concepts of surface free energy have been used. The results of the mechanical tests indicated that the PB additive has increased the strength of the asphalt mixtures against moisture damage. The results of the SFE method also indicated that Polybutylene additive improved the adhesion between asphalt binders and acidic aggregates which were susceptible to moisture damage. Also, using Polybutylene increased the cohesion free energy, which increased the asphalt binder film strength against cohesion failure. Moreover, the calculations based on thermodynamic concepts indicated that the asphalt binder modification has reduced the debonding energy, which also represented the reduced tendency of the system to stripping. [ABSTRACT FROM AUTHOR]

The growing concern in minimizing the disorderly disposal of waste in nature has been influencing measures that seek to give new environmentally sustainable and economically viable purposes for these materials. The use of steel slag aggregate in road paving emerges as an alternative for reducing the storage of this material in industrial yards, as well as contributing to a significant reduction in the cost of building a flexible road pavement. This study aimed to verify the technical feasibility of using ferronickel slag as an aggregate in the composition of hot mix asphalt. To this end, physical, chemical, mineralogical and environmental characterization tests of ferronickel slag were performed. The asphalt mixtures were dosed in accordance with the Marshall methodology, using the DNIT Range C with the use of ferronickel slag in the granulometric portions corresponding to the coarse aggregate, fine and filler, and the petroleum asphalt cement (PAC) 50/70. Based on the results, it can be stated that ferronickel slag demonstrates technical feasibility to be used as an aggregate in the composition of hot mix asphalt, meeting the requirements established by Brazilian standardization. In addition, it is an excellent environmental alternative because it uses a material previously treated as an environmental liability, avoiding the exploration of new natural deposits of stone aggregates. [ABSTRACT FROM AUTHOR]

This paper presents numerical investigations into the mechanical behaviour of hot mix asphalt (HMA) through the use of finite element modelling simulations. HMA is a well-known composite medium containing a highly complex microstructure. The X-ray computed tomography images (CTI) method can lead to a numerical model that closely represents the actual internal HMA microstructure. Unfortunately, this technology is not available to most researchers in the field of composite materials. It is therefore preferable to seek other techniques that enable researchers to simulate the actual internal microstructure. The aim of this study is to examine a heterogeneous generation (HG) method capable of generating an artificial microstructure of complex materials, as opposed to the X-ray CTI method. Several numerical HMA models are derived based on both these methods. A comparison of the mechanical behaviour output at the global and local scales from the X-ray CTI and HG digital models shows good agreement, thus indicating that the HG method has proven its effectiveness in reproducing the actual internal HMA microstructure and in predicting the material mechanical properties at these two scales. [ABSTRACT FROM AUTHOR]

This work focuses on the use of a heterogeneous generation method in order to develop a micromechanical model of Hot Mix Asphalt (HMA) that takes into account the effects of characteristics at the interfacial zone (IZ), where aggregate surfaces come into contact with the mortar matrix. Numerical calculations are conducted to investigate the effect of IZ mechanical characteristics on both the overall viscoelastic response of HMA and the local scale behavior. First of all, the HMA is treated as a biphasic material composed of mortar and granular inclusions. Next, a third phase is added between these two at each point of aggregate/mortar contact. Elastic and viscoelastic behaviors are assigned to the aggregates and mortar, respectively. The mechanical behavior of IZ varies between that of the inclusions and the matrix. At the global scale, these numerical results demonstrate that the use of triphasic micromechanical models improves the predictive accuracy of the dynamic modulus. At the local scale, a significant strain variation was found in each model. These results justify our triphasic modeling approach whenever local zone characteristics are the subject of interest. [ABSTRACT FROM AUTHOR]

This paper analyses the water, the degree of saturation, and the void content effects on the fatigue behaviour of hot mix asphalt (HMA) samples mixed in the laboratory. Some results on stiffness are also given. Fatigue characterization was carried out through a uniaxial tension‐compression (T‐C) test performed in a controlled‐strain mode, at 10°C and 10 Hz, on cylindrical samples. Our results show that the stiffness is not significantly affected by the water. This finding could be attributed to the short period of immersion of samples in water, low testing temperature, low void content of tested samples, and high viscosity of bitumen used. Furthermore, the fatigue resistance of HMA partially saturated with water (PSW) is lower than the one obtained for dry materials. [ABSTRACT FROM AUTHOR]

In this study, four different additives (Styrene–butadiene–styrene (SBS), Trinidad Lake Asphalt (TLA), Iranian Gilsonite (IG) and American Gilsonite (AG)) were used in bitumen modification. The rheological properties of bitumen were improved with the additive usage, and the desired performance grade (PG 70-34) was achieved by using additives in pure bitumen (PG 58-34) at the indicated ratios. Wheel tracking tests and semi-circular bending tests were applied for hot mix asphalt (HMA) samples. The main results showed that all the additives increased resistance to permanent deformation of HMAs, and that TLA was the most effective additive. In addition, it was found from the semi-circular bending tests that deformation values of mixtures prepared with modified bitumens and subjected to long-term ageing decreased. As a result, long-term aged and modified bitumen mixtures exhibited more brittle behaviour. The increase in maximum load values led to an increase in the area under the load-strain curves. Thus, crack propagation resistance of mixtures prepared with modified binders was increased. [ABSTRACT FROM AUTHOR]

Growing urban populations and vehicle using increased the need for highperformance roads. For this reason, bitumen modification, which is one of the main components of commonly used bituminous hot mixtures (BSK), is made to improve performance properties and behavior of the bitumen. In this study; the use of pomace (olive oil waste), which emerged during the production of olive oil, in bitumen modification was investigated. Bitumen was modified by mixing pomace in 5 diffrent percentages by weight. To pomace modified bitumen, penetration test, softening point test, ductility test, elastic return test and specific gravity test were applied and performance values were compared with unmodified bitumen. Also obtained modified bitumen was used in mixtures and Superpave mix design was used for performans analysis of this mix. Indirect tensile strength test was applied to the obtained mixtures and the indirect tensile strength ratio (TSR) was calculated. It has been determined that the performance of the modified mixtures of pirina against moisture sensitivity is increased. In addition it was observed that the penetration values of the modified bitumen decreased and the softening point values increased. [ABSTRACT FROM AUTHOR]

This study investigated the effect of short-term and long-term ageing on the dynamic modulus of foamed warm mix asphalt (WMA) produced by water injection and traditional hot mix asphalt (HMA). Four asphalt binders (PG 64-22, PG 64-28, PG 70-22 and PG 76-22) and one aggregate (limestone NMAS 12.5 mm) were used in the preparation of the laboratory-produced asphalt mixtures. The short-term and long-term ageing of the asphalt mixtures were simulated using AASHTO R 30. The experimental test results showed lower dynamic modulus values for foamed WMA than those obtained for traditional HMA for both short-term and long-term oven-aged specimens. By comparing the dynamic modulus values of the short-term and long-term oven-aged specimens, it was observed that some mixtures, such as those prepared using PG 64-22, had a smaller increase in dynamic modulus for foamed WMA mixtures than traditional HMA mixtures, while a comparable increase in dynamic modulus for both foamed WMA and HMA was observed for other mixtures, such as those prepared using PG 70-22 and PG 76-22. This suggests that the binder type plays a significant role in determining the ageing characteristics of foamed WMA and HMA mixtures. [ABSTRACT FROM AUTHOR]

In this study, polyolefin-aramid fibers were used as an additive to modify the performance properties of asphalt mixtures. For this purpose, three percentages of the fiber (i.e., 0.025%, 0.05%, and 0.075%) were added to asphalt mixtures and the rutting, fatigue and cracking performance of the mixtures were evaluated using the dynamic creep, wheel track, indirect tensile fatigue, and semi-circular bending (SCB) fracture tests. The results showed that the rutting and cracking resistance improved incrementally by increasing the fiber content, and the fatigue performance enhanced by adding up to 0.05% fiber and then leveled out by increasing the amount of fiber. [ABSTRACT FROM AUTHOR]

In this paper, a study is conducted on several realistic models that have been developed to represent the effects of thickness variations of asphalt mixtures with respect to the time- and rate-dependent behaviour of asphalt concrete. To predict the response, the theory of viscoelasticity is employed and the computational framework is implemented into a 3D multilayer model to use in finite element method. Three asphalt depths have been assumed and laid under repeated loading. The load passes are kept to 500 pulses. Study on the goodness of cycle numbers shows 200 pulses are good enough and the response has been converged before 200. The simulations show that viscoelastic behaviour is more sensitive to thickness variations, and the tensile strain and compressive stress under the asphalt reduces faster than conventional designing assumptions; however, the viscoelastic final response is still greater. The results reveal that the base course is greatly influenced by asphalt thickness variations so that a 10 cm viscoelastic overlay causes basecourse to bear stress eight times greater than that of elastic assumption. The resulting compressive stress above the subgrade is significantly affected by asphalt thickness and stress-induced history. Moreover, the results show that the viscoelastic behaviour develops the stress overlapping zone. [ABSTRACT FROM AUTHOR]