Performance Of Asphalt Pavement Research Articles

Explainable highway performance degradation prediction model based on LSTM

With the dense and huge highway network in China, the highway maintenance management system has become the most concerned issue for Chinese highway managers in recent years. Therefore, based on the highway network in Guizhou Province of China, this paper established the semi-rigid asphalt pavement performance multi-output Long Short-Term Memory (LSTM) prediction model with regional applicability, including Pavement Surface Condition Index (PCI), Pavement Rutting Depth Index (RDI), Pavement Riding Quality Index (RQI) and Pavement Skidding Resistance Index (SRI) and the hyperparameters of the model were optimized by Bayesian optimization algorithm and the casual analysis of the model was conducted based on SHapley Additive exPlanations (SHAP), providing a reference for China's highway network-level preventive maintenance decision-making. The results prove that the established model can effectively predict the performance of the following year through the data of the previous two years. The established model has a better comprehensive prediction effect in comparison to similar multi-output models. The average coefficient of determination (R2) of the four prediction indexes can reach 0.823. Besides, the prediction effect among the indexes is stable and multiple pavement performance indexes can be effectively and reliably predicted at the same time. In addition, the contribution of input feature variables to output is quantified based on SHAP. According to quantified the contribution, the association relationship of the neural network model is set-valued mapped to the causality relationship in the post hoc. The input feature variables with the main contribution are extracted for causal analysis. The causal analysis shows that the degradation of the four pavement performances all have obvious time memory characteristics and have significant differences, but their pavement performance degradation is the result of nonlinear changes caused by the coupling effects of traffic load, road age, climate, and pavement structure.

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

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

Evaluating the Anti-Skid Performance of Asphalt Pavements with Basalt and Limestone Composite Aggregates: Testing and Prediction

Evaluating the Anti-Skid Performance of Asphalt Pavements with Basalt and Limestone Composite Aggregates: Testing and Prediction

Evaluation of degree of blending and interaction between aged and virgin asphalt binders using rheological and fracture measurements

Evaluating the blending and interaction processes between aged and virgin asphalt binders is significant for enhancing the performance and longevity of asphalt pavements, particularly when using Reclaimed Asphalt Pavement (RAP). The primary aim of this research is to investigate the optimal conditioning time for diffusion process between virgin and aged binders. To simulate age-hardened RAP binder, asphalt binders were artificially aged in a forced draft oven at 163 °C for five hours, followed by additional aging at 85 °C and 110 °C over periods of 5, 7, and 10 days. The research assessed the degree of blending and interaction between aged and virgin binders in two phases using rheological and fracture measurements. In the first phase, the study explored the effects of various conditioning temperatures and durations (135 °C and 165 °C for 15, 30, and 60 minutes) on the diffusion and blending of the asphalt binders. Results indicated that the interaction between aged and virgin binders depends on the temperature and duration of conditioning; notably, complete blending was achieved at 165 °C after 60 minutes. The second phase investigated the impact of aged binder content on the rheological and fracture characteristics of the blended binders. Findings showed that fracture energy and peak load decrease with an increase in aged binder content. Specifically, increasing the aged binder content from 10 % to 30 % resulted in an approximate 23 % reduction in fracture-related parameters, while increasing the aged binder content from 50 % to 70 % led to an approximate 51 % reduction. Additionally, analysis of the complex shear modulus across different blends revealed an increase in modulus and high-temperature performance proportional to the percentage of aged binder, suggesting a hardening effect in the blended binder. Overall, this study underscores the significance of understanding the interactions between aged and virgin binders to optimize the diffusion and blending processes, ultimately enhancing the performance of asphalt pavements containing recycled materials.

Low-temperature performance and micro-structure of warm mix recycled composite aged asphalt

Given the cold winters in Inner Mongolia, the low-temperature performance of asphalt pavement is one of the key factors affecting the service life of roads. This study focuses on commonly used SBS modified asphalt and investigates the coupling effect of adverse factors such as solar radiation, high temperature, and precipitation on road surface asphalt. The objective is offer insights for improving the applicability and service life of warm mix recycled asphalt in cold regions. By using indoor simulation aging equipment, asphalt subjected to hot oxygen aging, composite water aging, and composite ultraviolet aging was prepared to investigate the low-temperature performance of warm mix recycled asphalt. Additionally, to explore the synergistic effect of new asphalt, regenerant, and warm mix agent on the regeneration of aged asphalt, this study analyzes the low-temperature performance and microstructure changes of recycled asphalt through bending beam rheometer (BBR) test, atomic force microscopy (AFM) test, and infrared spectroscopy (FTIR) test. The results show that as the degree of aging increases, the low-temperature crack resistance performance of asphalt deteriorates. Additionally, after the regeneration of aged asphalt, the damping ratio and dissipation energy ratio of warm mix recycled asphalt slightly enhances compared to hot mix recycled asphalt. Furthermore, the incorporation of a warm mix agent enhances the asphalt’s fluidity, viscosity, surface toughness, and further its low-temperature performance. The AFM test results show that the synergistic effect of warm mix agents and regeneration effectively restores the microstructure and surface roughness of asphalt. Moreover, the warm mix agent improves the dispersion uniformity of the SBS modifier in asphalt, helping prevent the agglomeration of asphalt slurry. Qualitative and quantitative analysis of asphalt through FTIR test demonstrates that the mechanisms of warm mix agents and regeneration on new and aged asphalt are a physical process. New asphalt and regeneration supplement the internal lightweight components of aged asphalt, enabling the restoration of most asphalt without affecting the structure of SBS modified asphalt. This project provides a theoretical basis for the engineering applicability of high content warm mix recycled asphalt (composed of 50 % aged asphalt) in large temperature range areas.

Identification of asphalt binder tests for detecting variations in binder cracking performance

Asphalt binders are vital components in the construction of roadways, and their quality significantly impacts the performance and durability of asphalt mixtures. However, it is possible for binders to exhibit different performance with identical Performance Grade (PG) due to variations in source, refining processes, and modifiers (if any). This paper presents a comprehensive study aimed at identifying candidate tests to detect variances in the quality of the binders in terms of cracking resistance. Eight PG 64-22 asphalt binders were selected and subjected to multiple laboratory tests, including X-ray fluorescence (XRF), Dynamic Shear Rheometer (DSR), Poker chip, and Bending Beam Rheometer (BBR) tests. The binders were then incorporated into asphalt mixtures, and their cracking resistance was evaluated using the IDEAL cracking test (IDEAL-CT) and Overlay test (OT). The study findings revealed that phase angle test, poker chip test, and Glover–Rowe (G–R) parameter test emerged as promising candidates to detect variations in the quality of binders of the same grade based on their cracking resistance. Notably, phase angle and G-R tests, both utilizing DSR, offered valuable supplementary assessments to the traditional PG grading system, proving crucial in evaluating cracking resistance. Furthermore, the poker chip test, an affordable alternative to DSR, demonstrated its effectiveness in evaluating binder quality for cracking performance. In conclusion, the identified candidate tests provide valuable insights into evaluating the quality of asphalt binders. By incorporating these tests into mix design and evaluation processes, engineers can make informed decisions to optimize the performance and durability of asphalt pavements.

Enhancing self-healing of asphalt mixtures containing recycled concrete aggregates and reclaimed asphalt pavement using induction heating

Given the growing demand for sustainable road construction materials, this research aims to evaluate the synergistic effects of incorporating recycled concrete aggregate (RCA) and reclaimed asphalt pavement (RAP) in asphalt mixtures. Induction heating was also utilized to enhance the self-healing ability of asphalt mixtures, with the intention of prolonging their lifespan and mitigating environmental impacts. This research assessed the pavement performance of recycled asphalt mixtures (RAM) with different RCA and RAP dosages. The induction heating performance, cooling performance, and effective heating depth of RAM were tested. Lastly, the cumulative healing efficiency of the RAM was evaluated under multiple "fracture-healing" conditions. Findings indicated that the inclusion of RCA and RAP negatively influenced the water stability, high-temperature deformation resistance, and crack resistance at low temperatures of the RAM. However, when the RCA content was 20 % and the RAP content did not exceed 20 %, the road performance of the RAM met the requirements. The contents of the RCA and RAP had no discernible effect on the RAM's induction heating capability. Moreover, when the RCA content was 20 % and the RAP content did not exceed 10 %, the effective heating depth of the RAM could reach 50 mm. Using fracture energy recovery rate as the healing index, after three cycles of "fracture-healing", the RAM with 20 % RCA achieved the highest cumulative healing efficiency of 291 %. The cumulative healing efficiency of recycled asphalt mixtures with 20 % RCA and 10 % RAP was close to that of normal asphalt mixtures. This research contributes to reducing the consumption of non-renewable resources, minimizing environmental impact, and maintaining or even improving the performance of asphalt pavements by optimizing the use of RCA and RAP.

A probabilistic investigation of long-term field performance of warm mix asphalt pavements

Warm-mix asphalt (WMA) has been gaining popularity in sustainable road engineering due to its reduced environmental impacts. However, uncertainties remain regarding its long-term pavement performance compared to hot mix asphalt (HMA). Especially, the critical factors influencing the field performance of WMA are yet to be determined. Hence, this study analyzes the long-term field performance of pavement overlaid with WMA, using data from the Specific Pavement Studies 10 (SPS-10) of the long-term pavement performance (LTPP) program. The evaluation includes 58 field sections from nine projects across the United States, encompassing two WMA types (foaming processing and chemical additive) and their corresponding HMA control sections. Performance indicators such as alligator cracking, longitudinal cracking in the wheel path, transverse cracking, rutting, and roughness (measured by the international roughness index, IRI) were considered. Per-state and per-climate region Bayesian multilevel models were built to account for site- and region-level heterogeneity. The study results demonstrated that pavement with WMA performed equally well to the HMA counterparts under similar conditions, indicating that their potential for widespread application in meeting both performance standards and environmental conservation requirements. Also, WMA technologies did not differ in pavement performance, and thus the field performance of WMA was not a dominant factor in deciding WMA technology types. Furthermore, Bayesian multilevel models proved highly effective in performance data varying across construction sites and regions.

Evaluation of Fatigue Behavior of Asphalt Field Cores Using Discrete Element Modeling.

Fatigue cracking is one of the primary distresses of asphalt pavements, which significantly affects the asphalt pavement performance. The fatigue behavior of the asphalt mixture observed in the laboratory test can vary depending on the type of fatigue test and the dimension and shape of the test specimen. The variations can make it difficult to accurately evaluate the fatigue properties of the field asphalt concrete. Accordingly, this study proposed a reliable method to evaluate the fatigue behavior of the asphalt field cores based on discrete element modeling (DEM). The mesoscopic geometric model was built using discrete element software PFC (Particle Flow Code) and CT scan images of the asphalt field cores. The virtual fatigue test was simulated in accordance with the semi-circular bending (SCB) test. The mesoscopic parameters of the contacting model in the virtual test were determined through the uniaxial compression dynamic modulus test and SCB test. Based on the virtual SCB test, the displacement, contact forces, and crack growth were analyzed. The test results show that the fatigue life simulated in the virtual test was consistent with that of the SCB fatigue test. The fatigue cracks in the asphalt mixture were observed in three stages, i.e., crack initiation, crack propagation, and failure. It was found that the crack propagation stage consumes a significant portion of the fatigue life since the tensile contact forces mainly increase in this stage.

Real-time pavement temperature prediction through ensemble machine learning

Pavement temperature is crucial for assessing asphalt pavement's performance and structural integrity due to its viscoelastic behavior. Currently, asphalt temperature prediction includes analytical, numerical, and statistical methods and relies on field investigation with intensive labor and time to hinder routine practice. Machine learning (ML) offers a promising solution for reliable and accurate real-time predictions by considering various dynamic environmental factors. This research employs four ensemble ML algorithms: eXtreme Gradient Boosting (XGB), Light Gradient Boosting Machine (LGBM), Random Forest (RF), and Adaptive Boosting (AdaBoost) to predict pavement temperature at different depths. XGB consistently outperformed other ensemble models, boasting the highest average R2 value (97.92%) and lower MAE and RMSE than LGBM, RF, and AdaBoost. XGB also significantly outperformed other commonly used models (linear regression, SVR, ANN, LSTM, and GRU) with an average reduction in errors of 35.29%, 63.75%, 42.75%, and an increase in R2 by 4.39% for MAE, MSE, RMSE, and R2, respectively. The Shapley additive explanation (SHAP) was applied to interpret the underlying influencing factors and their interactions, and revealed atmospheric temperature as the most impactful feature, contributing over 40.58% among the significant features.Furthermore, the predictive performance of XGB was enhanced by incorporating Principal Component Analysis to reduce computational consumption with average reductions of 8.98%, 16.59%, 9.01%, and 7.89% in MAE, MSE, MAPE, and RMSE. XGB with PCA emerges as the most effective and efficient model for predicting pavement temperatures at various depths to facilitate timely decision-making for preventive maintenance and rehabilitation and prevent future catastrophic failures.

Logistic Simulations to Assess the Effect of Florida Department of Transportation’s Incentive and Disincentive Specifications on Long-Term Asphalt Pavement Performance

Logistic Simulations to Assess the Effect of Florida Department of Transportation’s Incentive and Disincentive Specifications on Long-Term Asphalt Pavement Performance

Analysis of viscoelastic behaviour in asphalt pavement through four-point beam bending tests

This study, conducted in accordance with ASTM T321-14 standards, offers crucial insights into the behaviour of asphalt materials subjected to cyclic loading. For proper maintenance and pavement design, it is essential to understand the material response under different loading conditions. This study focuses on the four-point beam bending test to investigate the viscoelastic behaviour of asphalt pavement. The four-point beam bending test is a useful method for determining the material's ability to withstand cyclic loading and deformation, which the material experiences during field traffic conditions. The experimental setup involves subjecting asphalt samples to cyclic loading using a four-point bending apparatus. The imposed load causes the specimen to experience bending strains, representing the actual loading conditions that pavements endure. The data gathered during testing include stress, strain, and deformation properties under various loading conditions. The stress-strain response demonstrates the material's resilience to fatigue, with a gradual decrease in stiffness beyond 10,300 cycles. Fatigue failure criteria include a 50% reduction in initial stiffness for strain-controlled fatigue tests and cracking in stress-controlled tests. The dynamic modulus in a compressive-type, repeated load test follows a three-phase pattern, highlighting the impact of temperature and binder characterization methods on sample performance. The results provide information about the material's resilience to rutting and fatigue cracking, the most significant distresses indicated in asphalt pavements. The findings from this study contribute to an in-depth understanding of the viscoelastic behaviour of asphalt pavement and can aid in the development of improved design guidelines and maintenance strategies characterizing the material response to cyclic loading. Engineers and researchers can make better decisions on the durability and performance of asphalt pavements, resulting in more cost-effective and sustainable road infrastructure.

The effect of moisture on the adhesion properties at the interface between asphalt and recycled aggregates

ABSTRACT The effect of moisture on the adhesion strength at the asphalt and recycled concrete aggregate (RCA) interface plays an important role in the durability performance of asphalt pavements. In this study, a universal testing machine was used to analyse the effect of moisture on the asphalt adhesion rate at the interface. Scanning electron microscopy was utilised to observe the changes in the micro-morphology of the interface before and after the effect of moisture. The effect of moisture on the interface between asphalt and recycled aggregate was investigated using molecular dynamics (MD) simulation to explore the microscopic mechanism. The results showed that the residual rate of asphalt on the surface of concrete specimens decreased from 80.2% to 34.7% after 72 h of water bath curing. The micro-morphology at the asphalt–RCA interface changed significantly before and after the action of water. Interfacial water affects the concentration distribution of asphalt components at the interface mainly by changing the nanostructure within the asphalt binder. This leads to worse adhesion properties at the asphalt–RCA interface. This study provides deeper insights into understanding water damage at the asphalt–RCA interface and provides ideas for improving the durability of the material.

The effect of moisture on the adhesion properties at the interface between asphalt and recycled aggregates

ABSTRACT The effect of moisture on the adhesion strength at the asphalt and recycled concrete aggregate (RCA) interface plays an important role in the durability performance of asphalt pavements. In this study, a universal testing machine was used to analyse the effect of moisture on the asphalt adhesion rate at the interface. Scanning electron microscopy was utilised to observe the changes in the micro-morphology of the interface before and after the effect of moisture. The effect of moisture on the interface between asphalt and recycled aggregate was investigated using molecular dynamics (MD) simulation to explore the microscopic mechanism. The results showed that the residual rate of asphalt on the surface of concrete specimens decreased from 80.2% to 34.7% after 72 h of water bath curing. The micro-morphology at the asphalt–RCA interface changed significantly before and after the action of water. Interfacial water affects the concentration distribution of asphalt components at the interface mainly by changing the nanostructure within the asphalt binder. This leads to worse adhesion properties at the asphalt–RCA interface. This study provides deeper insights into understanding water damage at the asphalt–RCA interface and provides ideas for improving the durability of the material.

Effect of nanowollastonite wastes on bitumen and asphalt mixtures performance

Wollastonite is a neutral mineral with a high modulus of elasticity that is composed of lime and silica in almost equal proportions, and the structure of this mineral is fibrous and needle shaped, which distinguishes it from other minerals. In recent years, extensive research has been conducted on nanomaterials as bitumen modifiers and asphalt mixtures. The effect of morphology and nanoscale waste mineral wollastonite as a bitumen additive on the properties of asphalt mixture was investigated. According to the test findings, the use of nanowollastonite increases the G* sin δ parameter between 2000 and 3700 kPa at room temperature, resulting in a 45% reduction in the fatigue failure factor. Additionally, the rutting factor, G*/sin δ, increases between 3.75 and 4.75 kPa, indicating that the presence of nanowollastonite extends the pavement rutting life by 20% at an optimal concentration of 4% nanowollastonite. The findings demonstrate that waste nanowollastonite can be introduced as a new waste material to enhance the performance of asphalt pavement, considering the shape and size of its nanocomponents. Furthermore, incorporating waste nanowollastonite in the present design of asphalt concrete has a significant impact on reducing energy usage. Encouraging the use of these waste nanoparticles is worthwhile to reduce global energy consumption and pollution.

Evaluating the Properties of Improved Asphalt Material and Hot Mixture Asphalt by Adopting Rotational Viscosity Test and Wheel Track Test

Scientists and engineers are continually attempting to enhance the performance of asphalt pavements by altering the asphalt. Because of their natural compatibility with asphalt cement as well as their exceptional properties, polymers may offer an excellent opportunity for asphalt modification to extend service life and reduce early distress by enhancing the properties of hot-mix asphalt. This study aims to explain how the various polymers influence the properties of hot mix asphalt with a wet procedure using asphalt produced locally at the Al-Durah refinery and various polymers. Styrene-butadiene-styrene (SBS), polytetrafluoroethylene (PTFE), polyvinyl chloride (PVC), and (PVC+SBS) are examples of these polymers. Three and five per cent of the polymer are utilized for SBS, PTFE, and PVC, respectively. The asphalt cement ratio for (SBS+PVC) was 2.5% by weight at various blending times. The polymer asphalt mixtures are evaluated using Wheel Track tests and then compared to the conventional mixture. The modification of bitumen with polymers enhanced its conventional properties, such as viscosity. In addition, it was determined that the mechanical properties of HMA prepared with PMB samples, as measured by wheel track experiments, improved with increasing polymer contents.

Effects of a Complex Environment on Fatigue and Self-Healing Characterization of Asphalt Composites Containing Rock Asphalt.

In recent years, asphalt pavement has been subjected to varied environmental conditions during its service life, conditions that predispose it to deformation and cracking. To enhance the performance of asphalt pavement, rock asphalt has been selected as a modifier due to its good compatibility with virgin asphalt binder and its ability to improve the fatigue cracking resistance of asphalt mixtures. Although scholars have conducted some studies on rock asphalt mixtures, research on the fatigue and self-healing performance of these mixtures under conditions such as ultraviolet (UV) aging and freeze-thaw remains limited. This paper presents findings from a study that employs a combined fatigue-healing test to assess the impact of such complex environmental factors on the fatigue and self-healing properties of fine aggregate matrix (FAM) mixtures containing three types of rock asphalts, i.e., Buton, Qingchuan (QC), and Uintaite Modifier (UM). The analysis of fatigue-healing test results, grounded in viscoelastic continuum damage (VECD) theory, indicates that rock asphalt can extend the fatigue life of FAM mixtures, albeit with a concomitant decrease in their self-healing capabilities. The study further reveals that UV aging, freeze-thaw, and UV aging-freeze-thaw conditions all led to a diminution in the fatigue and self-healing properties of FAM mixtures. However, FAM mixtures containing rock asphalt demonstrated greater resilience against these reductions. Atomic force microscope (AFM) results indicate that UV aging reduced the number of bee-structures and enlarged their area, whereas the incorporation of rock asphalt enhanced the uniformity of these structures' distribution, thereby improving the fatigue cracking resistance of FAM mixtures. Fourier transform infrared spectroscopy (FTIR) analysis reveals that while UV aging increased the carbonyl and sulfoxide indices within the asphalt binder, rock asphalt is effective in mitigating this effect to a certain degree, thereby enhancing the aging resistance of FAM mixtures.

Plant Waste-Based Bioadditive as an Antioxidant Agent and Rheological Modifier of Bitumen.

In recent times, circular economy initiatives in addition to the need for sustainable biomaterials have brought about several attempts at the eco-friendly, eco-sustainable and cost-effective production of asphalt pavements. It is an increasingly common practice in the asphalt industry to improve road pavement performance using additives to enhance the physico-chemical properties of bitumen, which performs the role of the binder in the asphalt mix. This paper evaluated the potential of a bio-based additive derived from olive leaf residue as a modifier and antioxidant agent for bitumen. Samples of neat, aged and doped aged bitumen were analyzed. In this study, the two bio-based additives were characterized in terms of phenol, chlorophyll, lignin and cellulose content, which was correlated with the mechanical properties of the tested samples. The mechanical properties of the neat, modified, aged and unaged samples were evaluated via Dynamic Shear Rheology. The bio-based additives proved to be promising and can improve the properties of bitumen binder and the performance of asphalt pavements in general.

Investigation of the effect of sediment clogging on the hydraulic conductivity of porous asphalt mixes using CFD and DEM methods

This study investigated the impact of sediment clogging on the hydraulic performance of porous asphalt (PA) pavements using a novel numerical approach combining the discrete element method (DEM) and computational fluid dynamics (CFD). In particular, image analysis techniques captured the morphology of real aggregates for the 3D appearance information. Then, the information was used to reproduce aggregates and their gradation in asphalt mixes using DEM, including sediments causing clogging of the PA. The samples in the DEM were transferred to CFD for hydraulic performance simulation. DEM samples were prepared with air voids content of 20% and 25%. Clogging particles with different sizes of 0.5 mm and 0.75 mm were used. The study found that clogging particles can move to deeper layers of the PA pavement but have a high potential to be trapped in upper layers and cause clogging issues in the top 5 mm and middle-to-bottom sections. Due to surface clogging, the air voids content for the 20% porosity PA sample was reduced by approximately 2% on average, whereas up to 7% reduction in air voids content was observed for the 25% PA sample. This led to 37.35% and 42.7% reduction in hydraulic permeability, respectively. The reduction in air voids content below 10 mm from the surface is negligible (0.3–0.7% reduction). Due to the clogging development inside the pore structure, the surface runoff on the top of the sample increases by 8.1% for the 20% air voids asphalt sample case and 37.5% for the 25% voids sample.

Physical, rheological and micro characteristics of ARA/Nano-TiO2 composite modified asphalt before and after short-term aging

This paper aims to investigate the composite application of nanomaterials and natural asphalt in order to enhance the road performance of asphalt pavement. The objective is to develop high-performance modified asphalt that improves the durability, reliability, and load resistance of asphalt roads while reducing resource waste and environmental pollution. The composite modified asphalt was prepared by adding different blends of Albanian natural rock asphalt (ARA) and 1% of nano titanium dioxide (Nano-TiO2), and the basic properties and rheological properties of the asphalt before and after aging were tested by using basic performance tests and temperature scanning tests. Subsequently, the microscopic morphological characteristics of the asphalt were observed by scanning electron microscope and atomic force microscope, and the number of bee structures, the area share of bee structures, root mean square roughness Rq, and arithmetic mean roughness Ra were used as microscopic quantitative indexes. The results indicate that the complex modulus and rutting coefficient of ARA/Nano-TiO2 composite-modified asphalt increase with an increase in ARA dosage when the dosage of Nano-TiO2 is 1%. The asphalt modified with Nano-TiO2 composite blended with 15% ARA exhibits higher residual needle penetration, composite modulus ratio, rutting coefficient ratio and lower softening point increment compared to 70# asphalt. The bitumen modified with titanium dioxide nanocomposite blended with 15% ARA exhibits higher Rq and Ra and a more stable phase structure before and after aging. 15% of ARA/Nano-TiO2 composite-modified asphalt has higher Rq and Ra before and after aging, and its phase structure is more stable. The results show that ARA/Nano-TiO2 composite-modified asphalt has better high-temperature deformation resistance and aging resistance than 70# and that 15% ARA is recommended as the optimum amount of composite-modified asphalt.