Asphalt Concrete Research Articles

TEKNOLOGI PENDETEKSI SUHU PADA BAN KENDARAAN BERBASIS SENSOR INFRARED PYROMETER UNTUK MENGURANGI RISIKO KECELAKAAN AKIBAT PECAH BAN

Rapid economic development and urbanization in Indonesia have resulted in an increase in the amount of transportation. The increasing number of transportation users is not balanced with the increase in driving awareness, thereby exacerbating transportation problems. This imbalance has caused driving safety in Indonesia to become a concern. This is proven by the increasing number of traffic accidents and causing many victims. As many as 73% of traffic accidents occur when the weather is sunny and hot. Road temperature affects the friction that occurs on vehicle tires. The friction that occurs between the tires and the asphalt road causes changes in the structure and thickness of the vehicle tires which can trigger tire rupture on the vehicle. Based on these problems, the innovation of a tire pressure and temperature detection device using an infrared pyrometer sensor has emerged with additional modifications that enable the tire pressure detection device to work optimally and provide convenience for its users.

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

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

ТЕХНОЛОГІЇ ХОЛОДНОГО РЕСАЙКЛІНГУ ДЛЯ ГЛИБОКОЇ РЕГЕНЕРАЦІЇ НЕЖОРСТКОГО ДОРОЖНЬОГО ОДЯГУ

ntroduction. In the introduction to the article, the briefly performed comparative analysis of the road asphalt concrete cold recycling technologies was adduced and also the actuality of the implementation of widened nomenclature of such technologies in the Ukraine was outlined. Problem statement. The issue of the article concerns processes and materials for technologies of the full-depth reclamation of flexible road pavements using cold recycling trough full depth of asphalt layer/layers including the underlying layers of granular materials as required. Purpose. The aim of the article is to analyze the technological parameters of processes of full-depth reclamation (FDR) and also general requirements for reclaimed materials especially those concerning the estimation of their thermorheological properties. Results. The methods of the reclaimed materials stabilization were examined which, in accordance with the FDR technologies, should be divided in mechanical and those performed with the stabilizing agents. The types of pavement defects were defined under presence of which the application of FDR technologies has been recognized highly effective. The concise analysis of general requirements for reclaimed materials was performed with setting off the materials subjected to special requirements for grading. Also, the technological particularities of processes of the full-depth reclamation were stated which should be attributed to the technical characteristics of road equipment, the road pavement condition, and reclaimed mixtures quantitative proportions as well. According to the analysis of the test methods of reclaimed materials stabilized by bitumen using foamed bitumen, the role of the thermoreological uniformity of cold recycled mixtures for their proper design was shown.

Life Cycle Assessment for the Use of Waste Plastics in Asphalt Concrete Mixes

Improper waste disposal poses the risk of contaminating natural water bodies and soil. The low recycling rate of plastics and their fate in landfills are significant global environmental concerns. Efforts to increase the use of recycled plastics worldwide aim to address the hazardous consequences of improper plastic treatment. One potential solution is incorporating plastics as binder or mixture modifiers in asphalt concrete (AC) mixtures, which repurposes waste plastics while reducing environmental impacts related to AC production. This study calculated the environmental impacts of repurposing waste plastics, specifically low-density polyethylene and polystyrene, into modifiers in AC mixes. Wet and dry processes were considered. The environmental impacts of plastic-modified AC mixes were compared with those of styrene-butadiene-styrene (SBS)-modified mixes. The life cycle assessment covered the following processes: (1) collection, sorting, and shredding of waste plastics; (2) transportation of waste plastics from landfill to recycling facility and then to the asphalt plant; (3) supply and transportation of virgin materials; (4) production of AC mixtures; (5) transport of material and equipment to site; and (6) onsite operations. The study concluded that waste plastic-modified mixes outperformed SBS-modified mixtures with regard to environmental performance, except for ozone depletion resulting from certain recycling process activities. The high-shear mixing in the wet process had a significant impact. Sensitivity analyses revealed the influence of binder content and material transportation on the overall environmental assessment.

Impact of Dynamic Wheel Loading on Flexible Pavement Responses for Non-Free Rolling Conditions

Since 2000, pavement design methodologies have transitioned from empirical to mechanistic-empirical procedures. However, the complexities of loading patterns, contact stress distribution, material characterization, vehicle maneuvering, and dynamic load amplification are still not fully considered, despite their significant effect on pavement performance. In this study, state-of-the-art numerical models were used to investigate the changes in critical pavement responses derived from the combined effect of roughness-induced dynamic loading and vehicle maneuvering. A decoupled vehicle–tire–pavement interaction approach composed of a random process to generate artificial road roughness profiles, a mechanical full truck model, and three-dimensional finite element tire and flexible pavement models allow the prediction of the impact of road roughness on vehicle dynamics. In addition, the study quantifies the effect of dynamic loading on contact stresses, and consequently, on pavement critical responses. Because of the expected increase in axle weight from truck electrification, overweight scenarios were also considered. Changes in load history and distribution of strain fields were assessed for two typical pavement structures (thin and thick). The combined effect of roughness-induced dynamic loading and vehicle maneuvering greatly altered the critical pavement responses associated with bottom-up fatigue cracking, near-surface cracking, and rutting. Under the most adverse conditions, the critical tensile strains at the bottom of the asphalt concrete increased up to 125%, the shear strain increased up to 100%, and the compressive strain escalated to 120% when compared with the reference cases. Higher temperatures exacerbated the impact of dynamic wheel loading and vehicle maneuvering.

Development of prediction model for structural behavior and gradation of porous asphalt pavement

This study is aimed at developing prediction model for structural behavior of Porous Asphalt Pavement (PAP) using ABAQUS software and also developing ANN (Artificial Neural Network) model to predict void percentages in Porous Asphalt mix gradations. Data from the past literatures were used to analyze various mixing parameters affecting the properties of Porous Asphalt gradation mixes. The study analyzed PAPs using KENPAVE software. The findings indicated that fewer allowable repetitions to fatigue and rutting failures were observed for thinner Porous Asphalt Concrete (PAC) layer thicknesses. This suggests that thicker PAC layers may offer better resistance to fatigue and rutting failures in pavement systems. The study found that the nature of subgrade material significantly influenced the rutting performance of PAP systems. Specifically, clayey soils exhibited a 77.74% reduction in the design life of the pavement compared to gravelly soil subgrades. This highlights the importance of considering subgrade characteristics in pavement design and construction to optimize pavement performance and longevity. Higher contact pressures resulted in higher tensile stresses at the bottom of PAC layer which in turn reduced the fatigue life of PAP. The findings from ABAQUS analysis indicated that an increase in the void percentage in Porous Asphalt Concrete (PAC) mixes led to a significant increase in horizontal tensile strain at the bottom of the PAC layer, with a 12.3% increase observed. Additionally, there was a noticeable increase in tensile strain for a PAC mix with 28% voids compared to a mix with 16% voids. This suggests that higher void percentages in the PAC mixes can potentially enhance the flexibility and deformation resistance of the pavement structure, which may contribute to improved performance under various loading conditions, hence leading to 92.8% reduction in allowable load repetitions to fatigue failure.The study further revealed that an increased void percentage in Porous Asphalt Concrete (PAC) mixes resulted in a decrease in vertical stress and deflection in the PAP system. However, no significant effect on the allowable repetitions to rutting failure was observed. This suggests that higher void percentages may lead to better load distribution and reduced vertical stresses within the pavement structure, contributing to improved performance in terms of stress and deflection.Moreover, Asphalt Pavement mixes were compiled to develop an Artificial Neural Network (ANN) prediction model. The results demonstrated good conformity between predicted and actual data, with a mean square error of 0.109 and a coefficient of correlation of 0.994. This indicates that the ANN model accurately predicts pavement performance based on the compiled asphalt pavement mixes, providing a valuable tool for pavement design and analysis.

Evaluation of fracture indices of warm mix asphalt (WMA) modified with nano-additive under pure shear and pure tear deformations

Cracks located on the road edge and curve are two pavement crack types that can reduce road safety. Providing a solution to control this type of crack can solve a large part of the concern in this case. This study innovatively bridges the research gap by evaluating the efficacy of nano-reduced graphene oxide powder (NRGOP) in enhancing the fracture resistance of warm mix asphalt (WMA) under various environmental conditions, a critical aspect previously unexplored in the pavement engineering literature. For this goal, asphalt mixtures containing different ratios of NRGOP were constructed. Then, a level of aging and damage induced by freeze–thaw were applied to the semicircular bend (SCB) and edge-notched disc bend (ENDB) specimens to understand how the changes in fracture strength, fracture crispiness, and fracture stiffness are under modes III and II (at + 15 °C and −15 °C). The finding revealed that the introduction of NRGOP increased the fracture properties of WMA mixtures, such as fracture energy (FEII or FEIII) and fracture toughness (KIIC or KIIIC), as well as fracture stiffness under pure shear and pure tear deformations. Laboratory findings at low temperatures showed that it is necessary to investigate KIIC and FEII for asphalt mixtures under non-conditions and freeze–thaw conditions. However, KIIC and FEIII were suggested for aging conditions. Therefore, in two-thirds of the results, FEII was critical, and in 100 % results, KIIIC was critical. At + 15 °C, KIIC and FEIII were more crucial for non-treated and freeze–thaw conditions, while KIIC and FEII were more critical for aging, respectively. Therefore, in two-thirds of the results, FEIII was critical, and in 100 % results, KIIC was critical. The results of this research provide insights to advance the socio-economics of pavements by controlling surface cracks in tropical and subtropical regions, which in turn increases ride quality, driver safety, and pavement maintenance costs.

Evaluation of asphalt film thickness and heavy metal leaching of oxidizing slag used as an aggregate material in dense-graded asphalt concrete.

Electric-arc-furnace (EAF) steelmaking uses scrap iron and steel as raw materials. Scrap iron and steel originate from complex sources and may contain heavy metal components which can leach into the environment over time due to wear-and-tear. A by-product of the EAF steelmaking process is oxidizing slag, and approximately 1.2 million metric tons is produced every year in Taiwan alone. This study investigated substitution of natural aggregates with oxidizing slag in dense-graded asphalt concrete. We evaluated the water resistance and asphalt film thickness of the oxidizing slag substituted asphalt concrete and further explored the performance of oxidizing slag as paving material. We determined the dissolved and total amounts of heavy metals in the oxidizing slag, comparing these results with current regulatory controls to assess the environmental compatibility of the oxidizing slag. We found that due to the complicated sources of oxidizing slag, the basic properties should be analyzed on a batch-to-batch basis. Furthermore, we recommend trial mixing before upscaling the production of oxidizing slag substituted dense-graded asphalt concrete to confirm the mixing time required to achieve uniformity. The results also show that in comparison to natural aggregates used in asphalt concrete, oxidizing slag exhibits superior performance in terms of increased asphalt film thickness and improved water resistance. Furthermore, oxidizing slag as an aggregate material was associated with decreased heavy metal leaching and reduced environmental pollution. The results of the toxicity characteristic leaching procedure (TCLP) met regulatory requirements. However, the microwave-assisted aqua-regia digestion procedure showed heavy metal concentrations exceeding the monitoring standards for food crops. Considering environmental compatibility, it is recommended that controlling the total amount of heavy metals in oxidizing slag should be included in regulatory requirements. Furthermore, we should prohibit the use of materials such as oxidizing slag and other steel furnace slag in the roadways adjacent to edible crop farmlands.

Coal-derived conductive pavement for winter de-icing: prototype, modeling, and simulation

Existing pavement de-icing methods result in high installation and maintenance costs, traffic delays, excessive weariness and corrosion, and negative environmental and safety impacts. To overcome these challenges, this paper presents an innovative pathway to designing and constructing smart self-heating pavements using a low-cost coal-char bearing asphalt material. The conductive asphalt incorporates coal char, i.e., a key byproduct of the coal pyrolysis process, into the Stone Mastic Asphalt (SMA) mixture. This asphalt containing coal-derived solid carbon exhibits highly tailorable electrical conductivity, satisfactory mechanical and thermophysical properties, and superior cost-efficiency as compared to other conductive pavement materials. The de-icing performance was also demonstrated by laboratory experiments on a bench-scale prototype. Furthermore, an efficient thermal network model was developed and validated by experiments to investigate the transient thermal behavior and energy performance of the Ohmic heating pavement system. The whole-year energy simulation case studies were conducted on a bridge pavement with an annual energy use of 24.6–1444.8 kWh/m2, showcasing its potential in field applications across cool humid, cold humid, and subarctic/arctic climate zones.

Tensile-Tear cracking resistance of RAP incorporated asphalt Mixtures, enhanced by Warm mix asphalt additive and nano calcium carbonate

Asphalt mixture is a commonly used material for road paving. However, its production is expensive and requires significant amounts of virgin materials. To address this issue, adopting a less harmful production process and incorporating recycled materials can be beneficial. In this study, the focus was on investigating the cracking resistance parameters of warm mix asphalt (WMA) mixtures prepared with high contents of reclaimed asphalt pavement (RAP), along with the use of nano calcium carbonate (NC) as a modifier. In this context, the cracking resistance of the mixtures was studied in two −12 and + 25 °C temperatures under pure mode I, two mixed modes I/III, and pure mode III loading. The results revealed that adding RAP increased the fracture toughness and fracture energy, with an average increase of 30 and 20 %, respectively. Incorporating NC also improved the mixture’s resistance to cracking, enhancing fracture energy by up to 30 % and fracture toughness by up to 20 %. The optimal content of NC was determined to be in the range of 2 to 4 %, depending on the variables considered. Considering the linear elastic fracture mechanics, several theoretical criteria were used to predict the fracture data, and accurate predictions were achieved. Statistical analyses were also conducted to evaluate the impact of variables on cracking resistance; as an example of outcomes, it is seen fracture energy of pure mode III is about twice the mode mode I.

The Effect of the Microstructure and Viscosity of Modified Bitumen on the Strength of Asphalt Concrete.

The purpose of these studies was to establish the influence of the microstructural and rheological characteristics of modified bitumen compositions on the strength indicators of asphalt concrete. The effect of additives concentration on the rheological characteristics and microstructure of binary "bitumen-surfactant", "bitumen-AG-4I", and ternary "bitumen-AG-4I-AG-4I" systems has been studied. To assess the effect of bitumen dispersion on the physical and mechanical characteristics of modified asphalt concrete samples, the compressive strength value was determined. The following chemicals have been used as additives: the original product AS-1, industrial additive AMDOR-10, and used sealant AG-4I, a product based on polyisobutylene and petroleum oils. At an increased content of AG-4I (C ≥ 1.0 g/dm3) in ternary systems, the contribution of the emerging intermolecular polyisobutylene network to the development of structuring processes increases while the viscous effect of the surfactant AS-1 decreases. It has been established that the minimum size of bee-like bitumen structures (1.66 µm) is recorded with the joint presence of additives in the bitumen, AS-1 at a level of 1.0 g/dm3 and AG-4I at a level of 1.0 g/dm3. Under the same concentration regimes of the ternary bitumen composition, the maximum increase in compressive strength RD was achieved with the smallest size of bee-like structures of modified bitumen.

Predicting the rutting behaviour of asphalt concrete in the modified wheel tracking test using DEM and a cohesive viscoelastic–elastoplastic-damage contact model

AbstractThis study used an advanced modelling approach capable of capturing the complex behaviour of asphalt concrete to model the modified wheel tracking test using a recent advanced experimental test set-up in accordance with ASTM D8292-20. The modelling approach uses the discrete element method (DEM) to naturally produce the heterogeneous internal structure and governs the behaviour of asphalt concrete at the grain level by an interparticle contact model. The contact model used is capable of characterising the rate and time dependency, viscoelastic-damage, and plastic-damage behaviour of asphalt concrete utilising the coupling of an elastoplastic-damage law with a viscoelastic-damage law. Unlike the conventional wheel tracking tests run in a fixed boundary condition (fully confined), the modified wheel tracking test considers the effect of boundary conditions on the rutting behaviour of asphalt mixes. Through comparisons and verifications with laboratory data of the rutting test at different boundary conditions (fully confined and unconfined), the modelling approach shows its capability of capturing the rutting behaviour of asphalt concrete in the modified wheel tracking test. Micromechanics analysis shows that the third (tertiary) stage of rutting behaviour is due to the weakening of the internal structure of the asphalt samples with contact bond breaks over time, which is found in the unconfined test. Meanwhile, the tertiary stage hardly occurs in the fully confined test once densification leads to contact of the aggregate–aggregate skeleton, forming a rigid structure to resist the load with lateral support from the fixed boundary condition. Finally, a parametric study was also conducted to provide further insight into the current testing set-up, including the effect of the sample size and boundary condition on the rutting behaviour of asphalt concrete.

Elevation Accuracy of Forest Road Maps Derived from Aerial Imaging, Airborne Laser Scanning and Mobile Laser Scanning Data

Forest road maps are a fundamental source of information for the sustainable management, protection, and public utilization of forests. However, the precision of these maps is crucial to their use. In this context, we assessed and compared the elevation accuracy of terrain on three forest road surfaces (i.e., asphalt, concrete, and stone), which were derived based on data from three remote sensing technologies (i.e., aerial imaging, airborne laser scanning, and mobile laser scanning) using five geospatial techniques (i.e., inverse distance; natural neighbor; and conversion by average, maximal, and minimal elevation value). Specifically, the elevation accuracy was assessed based on 700 points at which elevation was measured in the field, and these elevations were extracted from fifteen derived forest road maps with a resolution of 0.5 m. The highest precision was found on asphalt roads derived from mobile laser scanning data (RMSE from ±0.01 m to ±0.04 m) and airborne laser scanning data (RMSE from ±0.03 m to ±0.04 m). On the other hand, the lowest precision was found on all roads derived from aerial imaging data (RMSE from ±0.11 m to ±0.23 m). Furthermore, we found significant differences in elevation between the measured and derived terrains. However, the differences in elevation between specific techniques, such as inverse distance, natural neighbor, and conversion by average, were mostly random. Moreover, we found that airborne and mobile laser scanning technologies provided terrain on concrete and stone roads with random elevation differences. In these cases, it is possible to replace a specific technique or technology with one that is similar without significantly decreasing the elevation accuracy (α = 0.05).

Quantitative analysis of asphalt concrete’s tension-compression asymmetry effects on pavement response through 3D numerical modeling with dual viscoelastic model

Asphalt concrete (AC) exhibits noticeable tension-compression (TC) asymmetry, but it is typically considered isotropic in pavement design. This study aims to quantitatively evaluate the effect of AC’s TC asymmetry on pavement response under loading through numerical modeling. To achieve this objective, a temperature-dependent dual viscoelastic constitutive model was applied to incorporate AC’s TC asymmetry into pavement modeling. Besides, three pavement structure models, including one with thick AC layers, one with thin AC layers, and one with a Portland cement concrete (PCC) base, were developed. The responses of the three pavement structures under traffic and environmental loading conditions were simulated. Modeling results showed that AC’s TC asymmetry can significantly increase the vertical strain in AC, leading to higher stress concentration and larger deformation in AC layers. Unlike the conventional understanding that tensile strain concentrates at the bottom of AC layers, high tensile strains were observed in the top AC layers, especially for the pavement with thick AC layers or a PCC base, which may lead to top-down cracking. High tensile strains were observed on the granular subbase for the pavement with thin AC layers, which may induce bottom-up cracking. Besides, AC’s TC asymmetry also significantly increases the shear strains, especially the horizontal shear strain in AC layers, which may result in debonding and shoving distresses in AC layers. It was also noticed that the pavement response highly depends on its temperature and vehicular speed. A higher temperature or lower vehicular speed leads to more significant AC’s TC asymmetry as well as its effects on asphalt pavement’s response. The outcomes of this study are expected to help enhance the design and maintenance of more durable asphalt pavement.

Tribology-Based Specifications for Assessing the Production Temperatures of Asphalt Binder

The success of warm mix asphalt (WMA) technology and polymer-modified binders (PMB) depends on the accurate determination of the production temperatures. To date, no standard protocol has been developed to determine the production temperatures of the WMA technology. Recent studies have shown that the production temperature is related to the friction between the aggregate and asphalt binder, which can be explored using tribology. This study attempted to develop a tribology-based approach to evaluate the production temperature of WMA-modified binder and PMB. The ball-on-the-three-plate test was performed using different normal loads (1N, 3N, 5N, and 10N) and sliding speeds (0.05 m/s, 0.1 m/s, and 0.3 m/s). The test results were compared with the equi-viscous (EQ) method. Production temperatures obtained from the EQ method were inappropriate for WMA and PMB. Results of the tribology study showed that the normal load of 1N and 0.3 m/s was found suitable for evaluating the production temperatures. Adding WMA additives resulted in a lower coefficient of friction (CoF), whereas PMB showed higher CoF than viscosity grade binder (V8, which is used for WMA modification). The addition of WMA additive reduced the production temperatures of V8, and reduction was a function of the WMA additive type. Temperature ranges corresponding to the CoF of 0.26 ± 0.021 and 0.33 ± 0.023 were proposed for assessing the mixing and compaction temperatures, respectively.

Constitutive modelling and systematic evaluation of asphalt concrete’s viscoelastic tension-compression asymmetry effect on pavement performance

ABSTRACT Asphalt concrete (AC) exhibits significant tension-compression (TC) asymmetry, which is currently not considered in pavement design. This study develops a novel temperature-dependent dual viscoelastic model to quantitatively capture the viscoelastic behaviour of AC. Unlike the conventional viscoelastic constitutive model, the proposed model decomposes strain into tensile and compressive components to characterise AC’s TC asymmetry. Additionally, a systematic modelling framework with intrinsic TC asymmetry is developed for the first time to predict the response of pavement under moving tire load. The results illustrate that implementing the proposed dual viscoelastic model enlarges both the vertical deformation of pavements and the tensile and shear strains in the AC layers, bringing it closer to the realistic scenario compared to the conventional model that only considers compression properties. Furthermore, high temperatures and low vehicular speeds exacerbate the substantial effects of AC’s TC asymmetry on asphalt pavement. This study provides a valuable method to capture AC’s TC asymmetry and predict pavement response more accurately, giving better insight into pavement response and enhancing pavement design and maintenance.

Impact of Nonrecyclable Plastics on Asphalt Binders and Mixtures

Low-density polyethylene (LDPE) and polystyrene (PS) were evaluated for incorporation as binder additives to enhance the potential performance of asphalt concrete (AC) mixtures, as well as addressing global rising concerns over nonrecyclable plastics accumulation. Incorporation of LDPE and PS in asphalt binder resulted in an increase in its complex moduli over a range of temperatures and frequencies, as determined using frequency sweep (FS) and linear amplitude sweep (LAS) tests. AC performance tests were conducted, including the Hamburg wheel-tracking test (HWTT) to assess potential rutting, the Illinois flexibility index test (I-FIT) to determine cracking potential, the indirect tensile strength test (ITS) to assess moisture susceptibility, and the dynamic modulus for structural capacity. Two control AC mixes were designed, utilizing aggregates from different sources. For each AC mix, the aggregate blend and binder content were kept constant, with only the binder type changed. LDPE and PS were added through a wet process in one mix. Dry and wet processes were used in the other mix. Waste plastics–modified AC mixes, in both wet and dry processes, exhibited reduced rutting potential. However, the cracking potential and moisture damage susceptibility varied, depending on the modified AC mix. The addition of waste plastics had no impact on AC dynamic modulus. The results for waste plastics–modified AC mixes were compared with those for styrene-butadiene-styrene (SBS)–modified AC mixes. While waste plastics modification provided improvement over the control mixes, the performance fell short of that of the double-pump SBS-modified mix.

Feasibility Analysis of Resource Application of Dry Flue Gas Desulfurization Ash in Asphalt Pavement Materials

To verify the feasibility of applying dry flue gas desulfurization ash (DFGDA) to asphalt pavement materials, the asphalt mastic (filler and asphalt composition) prepared by adding different proportions of DFGDA and LSP (limestone powder) into 70# matrix asphalt was studied experimentally. The asphalt mastics were subjected to the penetration test, the softening point test, and the ductility test. Moreover, the rheological properties of asphalt mastic were evaluated with dynamic shear rheometer (DSR) tests and bending beam rheometer (BBR) tests. An interaction ability index C-value based on the Palierne model was proposed to evaluate the interaction ability between DFGDA and asphalt. The influence of DFGDA asphalt on the interaction ability of matrix asphalt was observed and evaluated using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results showed that with the increasing proportion of DFGDA, the penetration of asphalt mastic gradually decreased, the softening point increased, and the ductility slightly decreased. At the same temperature, the dynamic shear modulus G* of the asphalt mortar significantly increased with increasing DFGDA content. The incorporation of DFGDA negatively affected the low-temperature plastic deformation resistance of asphalt, but the impact was weakened with the growing DFGDA amount and the powder mastic ratio. The combination mode of DFGDA and matrix asphalt depends on the physical blending, and their interaction ability mainly depends on the miscibility between DFGDA and matrix asphalt. In conclusion, DFGDA can be utilized as a novel filler in asphalt pavement materials.

Tuning high- and low-temperature rheological properties of warm-mixing asphalt composites by functionalized waxes

Traditional asphalt road construction utilizes hot-mixing asphalt mixtures. High temperatures not only accelerate the aging of asphalt, but also produce large amounts of toxic and greenhouse gases. To alleviate these problems, wax-based warm-mixing agents are applied, and asphalt pavement construction temperatures can be efficiently lowered, resulting in lower energy and gas emissions. To systematically evaluate the effects of composition and structure of warm-mixing agents on rheological properties of asphalt at high and low temperatures, a series of functionalized waxes (i.e., oxygen-containing groups, amide groups, and long-chain aliphatic hydrocarbons) were designed in this work, followed by a melt-mixing process with asphalt. The findings demonstrated that warm-mixing agents with long-chain aliphatic hydrocarbons could significantly improve asphalt composites’ rheological properties at high temperatures, such as good viscosity-reducing effect and superior rutting resistance or permanent deformation resistance; warm-mixing agents with oxygen groups were able to improve the asphalt composites’ resistance to low-temperature cracking; amide group-containing warm-mixing agents could improve the surface roughness of asphalt composites. This work provides a practical guide for the selection of functionalized warm-mixing agents for asphalt pavement under multiple environmental factors.

Investigating the influence of polyethylene terephthalate fibres with different lengths on the cracking resistance of high-performance asphalt concrete

High-performance asphalt concrete is an innovative paving material that typically relies on the properties of polymer-modified asphalt binders. However, the application is limited due to their high cost and phase separation issues. A solution is explored in the present study by blending 12% asphaltenes and a straight-run asphalt binder with a true performance grade of 70.2–25.9, resulting in a true performance grade of 82.9–21.8, which elevates the binder’s stiffness. Three lengths of polyethylene terephthalate fibres are used to improve the cracking resistance of these asphaltenes-modified mixes. An indirect tensile cracking test is conducted at 25 and 37 °C, revealing a significant improvement in cracking tolerance and failure energy, particularly at 37 °C. The cracking tolerance index value peaked at 105 for 12 mm polyethylene terephthalate fabricated sample, while control asphaltenes-modified, 6 mm, and 18 mm polyethylene terephthalate fabricated samples achieved 61, 87, and 99, respectively, with failure energy increasing with longer fibres.