Hard Asphalt Research Articles

PERBANDINGAN NILAI KARAKTERISTIK MARSHALL UNTUK CAMPURAN AC-WC MENGGUNAKAN QUARRY AKANUNU DAN QUARRY HERA

Asphalt Concrete - Wearing Course (AC-WC) is a road construction layer consisting of coarse aggregate, fine aggregate, filler, and hard asphalt. This material is mixed, laid, and compacted at specific temperatures to form a durable and strong road surface layer. Enhancing road resilience against various factors causing damage is essential to maintain transportation systems and ensure even economic growth across regions. In this context, it's important to compare the physical and mechanical characteristics of AC-WC mixtures using materials from Quarry Akanunu and Quarry Hera. The aim of this study is to assess the performance of AC-WC mixtures from both quarries using the standard Marshall 2 x 75 blows testing method. The research findings indicate that using an optimal asphalt content of 5.85% from Quarry Akanunu, there are differences in Marshall characteristics compared to mixtures using materials from Quarry Hera. At an asphalt content of 5.85% from Quarry Akanunu, the differences in stability values reached 67.28 kg, flow 0.13 mm, VIM (Void in the Mix) 0.31%, VMA (Void in Mineral Aggregate) 0.14%, VFB (Void Filled with Bitumen) 1.22%, and Marshall Quotient (MQ) 31.43 Kg/mm. Meanwhile, using an optimal asphalt content of 5.90% from Quarry Hera, the differences in stability values reached 69.90 kg, flow 0.15 mm, VIM 0.31%, VMA 0.14%, VFA 1.22%, and MQ 33.12 Kg/mm. From this analysis, Quarry Hera shows slightly better performance in terms of stability and other Marshall characteristics compared to Quarry Akanunu, although both mixtures meet the specifications of Bina Marga 2018 revision 2.

A sustainable rapeseed oil-based bio-additive designed for hard asphalt binders: Performance, environmental, and economic assessment

The inherent properties of hard asphalt binder give it both mechanical and economic benefits, rendering it a naturally advantageous material for preventing permanent deformation at higher temperatures. However, its poor resistance to thermal and fatigue cracking limits its application in the paving industry. This study aimed to improve the low-temperature and fatigue performance of hard asphalt binders by using the newly developed vegetable oil-based sub-epoxidized rapeseed oil (SERO). Two SEROs with epoxidation degree of 49.1% and 98.1% were synthesized through an oxidation reaction, respectively. Subsequently, the microstructural characteristics of SEROs were examined by Fourier transform infrared spectroscopy (FTIR) and Hydrogen nuclear magnetic resonance tests. The anti-oxidative aging properties of SERO modified hard asphalt binders were investigated through the utilization of mass loss and aging index. Additionally, the comprehensive rheological properties of SERO modified hard asphalt binders were explored via dynamic shear rheometer and bending beam rheometer tests. Furthermore, the modification mechanism of SERO on hard asphalt binders was confirmed through the quantitative analysis using the FTIR test. The findings suggested the improvement in anti-volatilization and anti-oxidative aging performance of bio-modified hard asphalt binders, which was positively related to the epoxidation degree of SERO. A notable softening effect of SERO on the hard asphalt binders was observed, which enhanced their resistance to thermal and fatigue cracking at lower and intermediate temperatures. The epoxy groups within SERO engaged in ring-opening reactions, forming a new oxygen bridge bond by combining with the unsaturated double bond presented in the asphalt. Consequently, this process resulted in the formation of cross-linked structures within bio-modified hard asphalt binders, thereby enhancing the elasticity. Notably, this phenomenon was most conspicuous in the SERO-H modified 50# binder. Finally, the environmental and economic assessment of SERO modified hard asphalt binders were conducted by the techno-economic method and the emission factors technique. The data revealed that the production of one ton of SERO modified hard asphalt binders could reduce the production costs by about 30%, energy consumption and CO2 emissions by around 20% in contrast to styrene–butadiene–styrene block copolymer modified asphalt binders. Hence, the substantial economic and environmental advantages make SERO an attractive bio-renewable additive for sustainable pavements.

Effect of SARA Fractions on Fatigue Properties of Hard Asphalt.

The fatigue performance of hard asphalt is an important factor that affects the service life of asphalt pavement. In order to comprehensively explore the influence of chemical components on the fatigue performance of hard asphalt, and to eliminate the chemical instability between the microstructure of asphalt from different oil sources, seven kinds of hard asphalt were designed and prepared with saturates, aromatics, resins, and asphaltenes (SARA) extracted from the same hard asphalt. Rheological, time sweep and linear amplitude sweep (LAS) tests were carried out to evaluate the fatigue properties. The results show that the complex modulus of asphalt binds increased rapidly with an increase of asphaltene and resins and that the colloidal structure was strengthened, which would increase the fatigue factor. In the time sweep test, the strength of the colloidal structure significantly affected the fatigue life, and the fatigue life was different under different test stresses. In the viscoelastic continuum damage (VECD) model, the cumulative damage was related to the modulus, while with the increase of asphaltene and resins, the fatigue life showed a trend of first increasing and then decreasing. The linear regression analysis showed that the fatigue life of hard asphalt had a good correlation with strain sensitivity. This study investigated the applicability of different fatigue evaluation methods and revealed the influence of four components on the fatigue properties of hard asphalt. The results provide significant insights in the improvement of the fatigue performance of both hard asphalt and corresponding mixtures.

Phase Separation Study on the Storage of Technically Specification Natural Rubber Modified Bitumen

Overloading and climate change are often problems in pavement structures. For this reason, hard asphalt binders have high softening points, are elastic, and have good adhesion, which is needed to improve pavement performance. Asphalt binder performance can be enhanced by adding additives such as natural rubber or natural-rubber-modified asphalt. However, natural-rubber-modified asphalt shows poor storage stability problems. This is due to differences in density and viscosity between the constituent components of natural-rubber-modified asphalt. This study examines the phase separation mechanism in technically specified natural rubber (TSNR) modified asphalt. Prediction of the optimum storage length of modified asphalt before phase separation occurs, using a combined incompressible Navier–Stokes and phase field model and carried out with COMSOL Multiphysics software version 5.5. Experimental validation was conducted at TSNR levels of 8, 10, and 12% at 160 °C for 48 h, with and without sulfur. The simulation showed that the asphalt modified with TSNR experienced phase separation after 12 h of storage at 160 °C under conditions without stirring. This aligns with the experimental results, which showed phase separation at 160 °C after 48 h. Adding sulfur additives did not have much effect on improving storage stability. The combined incompressible Navier–Stokes and phase field model accurately describes the phase separation in TSNR-modified asphalt. The results of this research recommend that the industry store natural-rubber-modified asphalt in a constantly stirred condition to prevent phase separation of modified asphalt. In addition, the results of this research help the industry predict or increase the homogeneity of polymer-modified asphalt production and save time and costs.

Evaluation of hard petroleum asphalt's low-temperature performance and index optimisation based on the grey correlation model

Hard petroleum asphalt (HPA) has good application prospects because of its simple manufacturing process and excellent performance. However, according to previous studies, the performance of HPA at low temperatures cannot be well characterised by commonly used methods. The use of HPA in cold climates is severely constrained. In order to comprehensively evaluate the low-temperature performance of the material, this study used four different types of HPA as the research object, and used the bending beam rheological test ( BBR) to determine the basic rheological properties of the material. On this basis, after fitting and analysing the low-temperature creep compliance curve using the Burgers viscoelastic model, the asphalt was assigned a low-temperature viscoelastic assessment index. The glass transition temperature and sensitivity of HPA were investigated by differential scanning calorimetry (DSC). At the same time, the HPA assessment index at low temperatures was determined systematically by using grey correlation theory.

Performance evaluation of rapeseed oil-based derivatives modified hard asphalt binders: Towards greener and more sustainable asphalt additives

Hard asphalt binder is regarded as a favorable option in comparison to polymer-modified asphalt for rutting due to the benefits of cost-effectiveness and extreme stiffness behavior. However, its inherent poor ability to withstand fatigue damage and thermal cracking restricts its applications as a pavement material. This study aimed at enhancing the low-temperature and fatigue performance of hard asphalt binders with newly-developed rapeseed oil (RO)-based derivatives. Two rapeseed oil -based derivatives of epoxidized rapeseed oil (ERO) and acrylated epoxidized rapeseed oil (AERO) were laboratory synthesized through oxidation and ring-opening grafting reactions, respectively. Fourier transform infrared spectroscopy (FTIR) and Hydrogen nuclear magnetic resonance (1were conducted to confirm the successful synthesis of derivatives. Mass loss, aging index, performance grading, temperature-frequency sweep, linear amplitude sweep and bending beam rheometer test were employed to assess the modified effects of rapeseed oil-based derivatives on two types of hard asphalt binders. To further explore the differences between RO and derivatives, the properties of modified hard asphalt binders using two derivatives were compared against the performance of RO-modified hard asphalt binders. With the additional RO, ERO, and AERO, the modified hard asphalt binders had significantly improved the resistance to thermal cracking and fatigue damage at low and intermediate temperatures, respectively. RO was found to have the most positive effect on the stress relaxation and the most adverse effect on the stiffness of hard asphalt binders. While, ERO- and AERO-modified hard asphalt binders had shown better antioxidative and anti-aging performance than that of RO-modified hard asphalt binders. Additionally, AERO-modified hard asphalt binders were noticed to have improved the elasticity of hard asphalt binders owing to the formation of a polymer elastic network. According to the study, two rapeseed oil-based derivatives had shown great potential as green and sustainable asphalt modifiers on the improvement of thermal and fatigue cracking resistance with the minimal adverse effect on anti-rutting performance of the hard asphalt binders. The test results revealed that the rapeseed oil-based derivatives modified hard asphalt binders could be employed in various pavement applications with great economic and sustainable benefits.

Study on Aging Mechanism and High-Temperature Rheological Properties of Low-Grade Hard Asphalt.

In order to investigate the potential application of low-grade hard asphalt in high-temperature and high-altitude areas, various tests were conducted to analyze the performance and high-temperature rheological properties of 30#, 50#, and 70# matrix asphalt under thermo-oxidative aging and ultraviolet aging. The tests utilized for analysis included the examination of basic asphalt properties, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), gel permeation chromatography (GPC), dynamic shear rheology (DSR), and multi-stress creep recovery (MSCR). The results indicate a progressive decrease in asphalt performance with increasing aging time. Prolonged exposure to thermal oxygen aging and ultraviolet irradiation significantly diminishes the plasticity of asphalt. The carbonyl index and sulfoxide index of asphalt increase after thermal oxygen aging and ultraviolet aging. Notably, 30# asphalt demonstrates greater resistance to aging compared to 50# and 70# asphalt under long-term high ultraviolet radiation. The LMS% of 30#, 50#, and 70# asphalt increases by 14%, 15%, and 16%, respectively. Following photothermal oxidative aging, a larger proportion of lighter components in the asphalt transforms into resins and asphaltenes. The high-temperature rheological properties of the three types of asphalt rank as 30# > 50# > 70#, while within the same type of asphalt, the high-temperature rheological properties rank as PAV > UV3 > UV2 > UV1 > RTFOT > virgin. Elevating temperature, stress level, and stress duration negatively impact the high-temperature stability of asphalt. In general, low-grade asphalt demonstrates superior anti-aging ability and high-temperature rheological properties during the aging process.

Pengaruh Variasi Waktu Perendaman Terhadap Sifat Dan Karakteristik Campuran Aspal Panas Dengan Penambahan Styrofoam

Hot Rolled Sheet (HRS) According to the Ministry of Public Works (Bina Marga revision 2010), a thin layer of asphalt concrete (lataston) is a cover layer consisting of a mixture of gap graded aggregate, filler and hard asphalt with a certain ratio; which is mixed and hot compacted (within a certain temperature, a minimum of 124ºC). The purpose of this study was to determine the effect of variations in immersion time on the properties and characteristics of asphalt with Styrofoam added. This study used Styrofoam food waste with the addition of 5%, 10%, and 20%. Samples of specimens were made as many as 48 samples, 15 normal samples and 27 variations samples, 6 samples of remaining KAO. Treatment of the specimens was carried out with repeated immersion variations of 3, 7, and 14 days. The manufacture of test objects is hot mixed and refers to the 2018 Bina Marga Specifications, the test is carried out with the Marshall test equipment. The results of this test, indicate that the effect of Styrofoam waste as an additive in the HRS type asphalt mixture with repeated immersion can decrease the value of density, stability, MQ, and VFB. While the value of flow, VMA, and VIM increased

Analysis of Modulus Properties of High-Modulus Asphalt Mixture and Its New Evaluation Index of Rutting Resistance

High-modulus asphalt mixture (HMAM) is one of the most effective materials to enhance the rutting resistance of asphalt pavement and upgrade pavement sustainability. The objectives of this study are to investigate the modulus properties of different HMAMs and their correlation with the rutting resistance, to propose reasonable modulus evaluation indicators, and to analyze the rutting resistance mechanisms of different materials (hard asphalt, polyethylene, dissolved polyolefin). The effect of three HMAMs and two styrene-butadiene-styrene (SBS) modifiers on asphalt mixtures’ rutting resistance were evaluated by dynamic modulus test and wheel track test, and the results were simulated and further analyzed via ABAQUS. The results indicate that the dynamic modulus of the mixtures showed a gradual increase and decrease with the increase of loading frequency and testing temperature, respectively. The ratio of dynamic modulus in low frequency to that in high frequency correlates well with dynamic stability under high-temperature conditions, and the wider the frequency coverage, the higher the correlation between this ratio and dynamic stability. The rutting resistance of asphalt pavements can be improved by reducing the frequency sensitivity of HMAMs under high temperatures or by increasing the modulus’ absolute value of the pavement structural layer. Therefore, two indicators, the absolute value of the modulus and the ratio of 0.1 Hz dynamic modulus to 25 Hz dynamic modulus at 55 °C, are recommended for the evaluation of rutting resistance of HMAMs. Based on the evaluation indexes proposed in this paper, a comparative analysis of the rutting resistance mechanism of HMAMs prepared with different materials was carried out, and it was concluded that the mixture with high-modulus agents had the best rutting resistance, which is consistent with the test road observations, thus verifying the feasibility of the modulus evaluation indexes recommended in this paper for the evaluation of the rutting resistance of different types of HMAMs.

Experimental and molecular dynamics simulation of hard asphalt microstructure

To better design and application of hard asphalt, the conventional properties tests, SARA composition experiments, 1H NMR experiments, and elemental analysis were carried out for five types of hard asphalt and three types of virgin asphalt, and correlation analysis was performed. Systemic molecular dynamics were applied to reveal the microstructure characteristics by producing the density map and the mean square Displacement. The results indicated that the resins component and the number of saturated carbon in the molecular structure are closely related to the high-temperature performance. Meanwhile, the aromatics component and the number of branches connected to the aromatics rings in the molecular system are closely related to the low-temperature performance. Short, unordered planar accumulations dominate the asphalt microstructure. The variation coefficient of the density map follows the same trend as the CII values when characterizing the dispersion ability of the resins and aromatics components. The variation coefficient shows that the saturates components have more significant aggregation behavior than the asphaltenes component. The viscous behavior of asphalt cannot be directly characterized by microstructural distribution but requires further attention to the intermolecular forces within the microstructure.

Study on high temperature performance of coal based modified asphalt mixture

SHA, as a solid waste from direct coal liquefaction, has a certain application prospect. Based on the original concept and process of coal based clean asphalt preparation, this paper studies the performance of SHA coal based modified asphalt mixture, and draws the following conclusions: (1) SHA modified asphalt has the characteristics of hard asphalt (2) Compared with traditional SBS modified asphalt mixture, SHA modified asphalt mixture has good high temperature performance (3) SHA modified asphalt mixture has small rutting rolling depth, which can improve the rutting resistance of asphalt pavement.

Learning quadrupedal locomotion on deformable terrain.

Simulation-based reinforcement learning approaches are leading the next innovations in legged robot control. However, the resulting control policies are still not applicable on soft and deformable terrains, especially at high speed. The primary reason is that reinforcement learning approaches, in general, are not effective beyond the data distribution: The agent cannot perform well in environments that it has not experienced. To this end, we introduce a versatile and computationally efficient granular media model for reinforcement learning. Our model can be parameterized to represent diverse types of terrain from very soft beach sand to hard asphalt. In addition, we introduce an adaptive control architecture that can implicitly identify the terrain properties as the robot feels the terrain. The identified parameters are then used to boost the locomotion performance of the legged robot. We applied our techniques to the Raibo robot, a dynamic quadrupedal robot developed in-house. The trained networks demonstrated high-speed locomotion capabilities on deformable terrains: The robot was able to run on soft beach sand at 3.03 meters per second although the feet were completely buried in the sand during the stance phase. We also demonstrate its ability to generalize to different terrains by presenting running experiments on vinyl tile flooring, athletic track, grass, and a soft air mattress.

Electromyography of the multifidus muscle in horses trotting over firm and soft surfaces

Equine sports medicine has developed a focus on the multifidus muscle with little reported knowledge of its activity in normal horses. Our main aim and objective was to use in-dwelling electromyography (EMG) to measure and compare the average and peak activity of the multifidus muscle at the level of the 12th (T12) and 18th thoracic (T18) and 5th lumbar (L5) vertebra bilaterally. We hypothesized that trotting horses in hand over a soft deformable surface would cause an increase in both average and peak activity when compared to trotting on a non-deformable asphalt surface. The EMG signals from four horses each with 25 observable muscle contractions at each location were filtered and normalized to the maximum observed signals. The effect of two surface conditions on the average and peak muscle activity within each muscle section of four horses was assessed using unpaired t-tests. The average muscle activity was significantly higher while trotting over a soft surface when compared to the hard asphalt surface in the right T12 (mean difference [MD]=0.13 p < 0.001), right L5 (MD=0.12 p < 0.001) and left L5 (MD=0.18 p < 0.001) regions, although the left T12 location showed significantly higher average activity on the hard surface (MD=0.13 p < 0.001). The peak activity was significantly higher on soft footing in the left T18 (MD=0.10 p < 0.05), left L5 (MD=0.18 p < 0.001), right T12 (MD= 0.40 p < 0.001), and right L5 (MD=0.10 p < 0.001). Therefore, when compared to trotting on a hard surface, the softer surface induced higher levels of muscle activity in most of the multifidi locations.

Assessment on the applicability of heavy oil advanced refining byproducts for bituminous road pavements

Vacuum tower bottom/vacuum residue (VTB/VR), a byproduct of petroleum refining, is a hard and brittle asphalt material. If directly applied to road pavements, it can lead to early crack damage. Thus, this study developed a softening additive to reduce its brittleness and, in conjunction, laboratory experiments were employed to explore the fundamental characteristics of the VTB, VR, and traditional asphalt binder (PG 64–22). A method for determining the VTB/VR mixing ratio and softening additive ratio, such that the resulting material satisfies the present standards for road pavement asphalts in South Korea. In the mix design procedure, the softening ingredient was adjusted between 0%, 2%, and 4% by mixture weight while the VR mixing ratios were varied in increments of 10% by weight of VTB. The test results reveal that the penetration value of VTB can reduce linearly with the addition of VR compound. By using proper polypropylene glycol admixture, the findings confirm that VTB/VR mixture was a potential material for paving roads since this mixture meets almost all fundamental properties compared to conventional asphalt mixture. Especially, the dynamic modulus of the VTB/VR mixture was approximately 10% greater than that of the control at low temperatures. Based on varying amounts of softening additive and the maximum input amount of VTB that satisfied the PG 64–22 grade, the ideal VTB/VR mixture consists of 70% VTB, 30% VR, and 2% softening additive. The proposed asphalt alternative was also evaluated through field test construction, where it demonstrated its feasibility as an alternative to conventional road pavement asphalt.

Evaluation of High-Temperature Performance Indexes of Anti-rutting Asphalt Mixture

Abstract Because of frequent high-temperature weather and increased traffic volume, the rutting of asphalt pavement has become the main technical problem to be resolved. In this paper, seven types of anti-rutting asphalt mixtures, including masterbatch hard asphalt mixture with high-modulus, additive-type anti-rutting asphalt mixture, styrene-butadiene-styrene modified asphalt, and intersection anti-pushing asphalt mixtures A, B, C, and D were proposed. The Chinese and French rutting tests, the flow number test, the evaluation method of anti-pushing performance, and the structural depth attenuation test were used to evaluate the applicability of the following anti-rutting test methods: the evaluation methods and indicators of anti-displacement performance and the evaluation methods and indicators of structural depth attenuation under high-temperature conditions. The test results showed that the dynamic stability (DS) index of the Chinese rutting test was more suitable for evaluating the first stage of rutting development, and the DS index was more suitable for evaluating the second stage of rutting development than the creep rate of the French rutting test. It was reasonable to use the French evaluation method for asphalt concrete (AC) mixtures. The Chinese rutting test was more suitable for the high-modulus asphalt mixture. In addition, improving the high-temperature stability of the asphalt mixture can slow down the attenuation of the anti-slipping property.

Investigating properties and intermolecular interactions of sludge bio-oil modified asphalt

Bio-asphalt is a binder composed of bio-oil and petroleum asphalt under certain conditions. In this study, sludge bio-oil (wt 10%) was added into matrix asphalt to prepare sludge bio-asphalt for the first time. The effects of sludge bio-oil on asphalt performance and the essence of interaction between components were investigated using performance test, molecular dynamics (MD) simulation, and density functional theory (DFT). Chemical analysis showed that the ester compound containing ester functional group (COOH) was the main component of sludge bio-oil. Physical and rheological tests were performed to examine whether the properties of sludge bio-asphalt could be improved. The results found that sludge bio-oil can be used to soften the hard asphalt. Furthermore, the existence of bio-oil reduced complex modulus G* of master curves and stiffness, also increased Jnr and m-value, which means that sludge bio-oil had a positive effect on the low-temperature thermal cracking resistance performance while sacrificing the high-temperature rutting resistance performance to some extent. Fourier infrared spectroscopy (FTIR) and fluorescence spectrum (FM) analysis indicated that sludge bio-oil evenly dispersed in the asphalt, and the bio-asphalt structure resembled that of the conventional binder. The results of MD simulation further showed that O atom of COOH and H atom in the asphalt molecules formed hydrogen bond (OH⋯O, OH⋯C) interaction. This changed originally existed conformational packing of agglomeration and further prevented the agglomeration of component molecules. In addition, the analysis of cohesive energy density (CED) and solubility parameters (SP) revealed that sludge bio-oil significantly influenced the compatibility of asphaltene-asphaltene, resin-resin, and asphaltene-resin components. These, in turn, may explain some of the observed improvements in rheological properties.

Moisture Stability of Hard Sandstone Asphalt Mixture Based on APT with MMLS3

To evaluate the moisture stability of a hard sandstone asphalt mixture, a testing section of a hard sandstone asphalt mixture was prepared in the laboratory. The accelerated pavement testing (APT) with the one-third-scale model mobile load simulator (MMLS3) was conducted in this testing section under temperature and water-coupled conditions. As the APT number increased, the elastic modulus of the hard sandstone asphalt mixture pavement gradually decreased. The average elastic modulus was 22.99 GPa after 160000 APT cycles. The bulk specific density of the sample rolled by the MMLS3 increased, and the residual indirect tensile strength ratio was 88.7%. Therefore, the hard sandstone asphalt mixture had good resistance to moisture damage, and hard sandstone aggregates can be used in a hot mix of asphalt.

Pengaruh Penggunaan Serbuk Kaca Terhadap Karakteristik Marshall Campuran HRS-WC

HRS is a mixture consisting of hard asphalt and coarse, fine aggregate, and filler. One of the wastes that have not been used optimally is glass powder. When viewed physically, glass powder has small particles and, material weight is large enough to complete the requirements as a filler for asphalt mixtures. This study aims to determine the effect of glass powder on marshall characteristics, namely density, stability, VMA, VIM, VFB, flow, and MQ. This research method includes the preparation of materials and tools followed by testing of coarse aggregate, fine aggregate, and filler. After asphalt mix design for marshall testing to obtain the Optimum Asphalt Content (KAO) that will be used for the test object is 9 pieces with a ratio of 25%, 50%, and 75% glass powder filler from a total weight of 3% as a partial replacement of cement in the HRS-WC mixture. The results showed that the flow value of 3.7 mm had completed the requirements for using 50% glass powder filler. The use of 75% glass powder filler produces an MQ value of 369,124 Kg/mm. Whereas VIM and VFB values in the use of a combination of 25%, 50%, 75% glass powder filler don’t comply with the requirements specifications of Bina Marga 2018 revision 2. In general, the glass powder cann’t use as an alternative to cement filler

Characterization of fatigue performance of cold mix recycled asphalt mixtures through uniaxial tension–compression testing

Cold recycling of pavements utilizes nearly 100% of the reclaimed asphalt pavement (RAP) for pavement rehabilitation. Due to the large amount of RAP, the cold recycled mixes would become prone to fatigue cracking, and hence evaluation of their fatigue performance becomes highly important. In this study, three cold recycled asphalt mixes were prepared using a regular cationic slow setting asphalt emulsions with hard base asphalt binder (CSS-1h) with and without Portland cement stabilization, and a polymer modified emulsion (CSS-1hp). The optimum emulsion and pre-mix water contents were determined using Superpave Gyratory compacted specimens through the mix design process by studying the air void levels and meeting minimum strength requirements. Fatigue properties of these three groups of mixes were then evaluated through a series of uniaxial cyclic tension–compression tests. The results were compared in terms of the modulus degradation, dissipated energy capacity, changes in phase angle, and number of cycles to failure, to determine the fatigue lives of the different mixes. The results indicated that adding 1% Portland cement to the cold recycled specimens significantly improved their fatigue performance as compared to the control scenario specimens prepared with regular CSS-1h emulsion. Using the polymer modified emulsion also led to a slightly improved fatigue resistance of the cold mix specimens as compared to the mixes prepared with regular emulsion. Furthermore, Multiple Stress Creep Recovery (MSCR) testing of the two residual emulsion binders indicated potential of improving the rutting resistance for the mixes prepared with the polymer modified emulsion.

Comparative Study on Road Performance of Low-Grade Hard Asphalt and Mixture in China and France

The high-modulus asphalt mixture produced by hard asphalt has played a good role in reducing asphalt pavement rutting and improving pavement durability. It was widely used in the construction of various levels of road engineering in Europe. However, low-grade hard asphalt was rarely used in road engineering in China, and the use of hard asphalt for the design and construction of high modulus asphalt mixtures lacks sufficient engineering experience. Considering the above issues, comparative research on the performance of Chinese and French low-grade hard asphalt and mixture was carried out. In this paper, the performance of French 15# hard asphalt commonly used for EME (Enrobés à Module Elevé Class) high modulus asphalt mixture and China 15# hard asphalt was analyzed comparatively, where six typical high modulus asphalt mixtures corresponding to two low-grade hard asphalts were designed referring to the design requirements of French high modulus asphalt mixtures. The road performance of a high-modulus asphalt mixture was evaluated to verify the feasibility of its application in engineering. The research results show that the performance indicators of both Chinese and French asphalts meet the requirements of binder materials used in high modulus asphalt mixtures, and the performance of their corresponding mixtures of the two asphalts also meet the specifications of high modulus asphalt mixtures. However, the two asphalts and the performance of their corresponding mixture are slightly different. The high modulus asphalt mixture of Chinese low-grade hard bitumen can be used well in road engineering applications in China. It can strongly promote the wide application of high modulus asphalt mixture in China.