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15 pages, 2951 KiB

Open AccessArticle

Research on the Fracture Characteristics of Asphalt Mixtures in High Altitude and Cold Regions with Large Temperature Differences

by Shuangjie Wang, Haibo Cao, Tuanjie Chen, Wenhao Ke and Wu Bo

Coatings 2023, 13(3), 618; https://doi.org/10.3390/coatings13030618 - 14 Mar 2023

Cited by 4 | Viewed by 1614

Abstract

Due to the harsh climatic conditions in high altitude and cold regions with large temperature differences, asphalt pavement is generally prone to cracking, and the cracks propagate rapidly, which reduces the service life and service level of the road. The factors influencing the [...] Read more.

Due to the harsh climatic conditions in high altitude and cold regions with large temperature differences, asphalt pavement is generally prone to cracking, and the cracks propagate rapidly, which reduces the service life and service level of the road. The factors influencing the fracture characteristics of asphalt mixtures were analyzed in this paper, and the mixtures with different aggregate gradations from various types of asphalt were prepared. The fracture characteristics were explored using the thermal stress restrained specimen test (TSRST) and low-temperature bending test, and the good consistency of the low-temperature fracture performance was identified according to the results of frost-break temperature, flexural strength, and fracture toughness. The frost-break temperature was confirmed as the best indicator of the material crack resistance and could be used as the index to evaluate the performance of asphalt mixtures at low temperatures. The frost-break temperature of matrix asphalt mixture is 8–10 °C higher than that of modified asphalt mixture, and AC asphalt mixture is 2–4 °C higher than that of SMA asphalt mixture. The excellent asphalt performance has a more important influence on the fracture characteristics of asphalt mixture. The asphalt mixture of the same type had similar fracture toughness at varying notch depths, the most deviation is 3.78% which shows that the initial crack depth has little effect on the fracture toughness of asphalt mixture at low temperature. The results of the study can provide a basis for the selection of asphalt pavement surface materials and the optimization of mixtures in high altitude and cold regions with large temperature differences. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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11 pages, 3250 KiB

Open AccessArticle

Encapsulation for Sensing Element and Its Application in Asphalt Road Monitoring

by Chuanyi Ma, Xue Xin, Ning Zhang, Jianjiang Wang, Chuan Wang, Ming Liang, Yunfeng Zhang and Zhanyong Yao

Coatings 2023, 13(2), 390; https://doi.org/10.3390/coatings13020390 - 8 Feb 2023

Cited by 3 | Viewed by 1485

Abstract

The internal pavement structure is a “black box”; an accurate strain response for the pavement interlayer structure under vehicle load is hard to obtain by conventional road surface detection methods. This is due to the true strain field of the pavement structure, which [...] Read more.

The internal pavement structure is a “black box”; an accurate strain response for the pavement interlayer structure under vehicle load is hard to obtain by conventional road surface detection methods. This is due to the true strain field of the pavement structure, which means that the service state of the pavement cannot be accurately evaluated. This paper proposes an innovative strain sensor based on a carbon nanotube and epoxy (CNT/EP) composite to solve the current strain monitoring problem in asphalt pavement health monitoring. The CNT/EP composite encapsulation method was proposed, and the I-shaped strain sensor for asphalt pavement structure was developed. The strain–resistance response characteristics of the self-developed sensor were further investigated using a universal testing machine. The encapsulated sensor was used to monitor the strain of the asphalt mixture by means of a laboratory asphalt concrete beam and a practical pavement field. The results showed that the encapsulation method proposed in the study is suitable for CNT/EP material, which could guarantee the survivability and monitoring effectiveness of the self-developed sensor under the harsh environment of high temperature and pressure of asphalt mixture paving. The resistance of encapsulated sensor presents a linear relationship with strain. The laboratory and practical paving verified the feasibility of the self-sensor for strain monitoring of asphalt pavement. Compared to other post-excavating buried sensors, the self-developed sensor can be embedded in the pavement interlayer as the asphalt mixtures paving process, which can obtain the real strain response of pavement structure and reduce the perturbation of the sensor to the dynamic response of the pavement. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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14 pages, 8441 KiB

Open AccessArticle

Preparation and Performance Test of UV Resistant Composite-Modified Asphalt

by Quanjun Shen, Shijie Ma, Yaohui Yang, Liang Fan, Yongzhen Li and Pinhui Zhao

Coatings 2023, 13(2), 239; https://doi.org/10.3390/coatings13020239 - 19 Jan 2023

Cited by 2 | Viewed by 1649

Abstract

Ultraviolet radiation is the main cause of degradation in asphalt pavement. To improve the performance of the pavement used in the strong ultraviolet (UV) region of the western plateau, China, this study explores the effects of adding nano-montmorillonite and carbon black to SBS-modified [...] Read more.

Ultraviolet radiation is the main cause of degradation in asphalt pavement. To improve the performance of the pavement used in the strong ultraviolet (UV) region of the western plateau, China, this study explores the effects of adding nano-montmorillonite and carbon black to SBS-modified asphalt. Through conventional index detection, dynamic shear rheological tests, low-temperature bending creep tests, and UV aging tests, the high- and low-temperature performance, fatigue performance, UV aging resistance, and other aspects of the asphalt were studied. Various performance and price factors were considered in the optimization of various UV resistant composite-modified asphalt formulas. Increasing the contents of nano-montmorillonite and carbon black increases the high-temperature performance and the UV aging resistance but reduces the low-temperature and fatigue performance of asphalt; hence, their total content should be limited to <4%. Nano-montmorillonite has a better high-temperature performance and UV aging resistance than carbon black and is also less favorable to low-temperature and fatigue performance. Hence, it is recommended that its content not exceed 3%. UV resistant composite-modified asphalt has obvious advantages in high-temperature performance and UV aging resistance compared with conventional SBS-modified asphalt, and its low-temperature performance meets the use requirements of the strong-UV areas in the western plateau. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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15 pages, 3484 KiB

Open AccessArticle

Performance and Verification of High-Modulus Asphalt Modified by Styrene-Butadiene-Styrene Block Copolymer (SBS) and Rock Asphalt

by Yuxin Li, Xiangpeng Yan, Jianmin Guo, Wenjuan Wu, Wencheng Shi, Qinsheng Xu and Zhengjun Ji

Coatings 2023, 13(1), 38; https://doi.org/10.3390/coatings13010038 - 26 Dec 2022

Cited by 4 | Viewed by 1901

Abstract

High asphalt grade and poor high-temperature performance are the primary reasons for the permanent rutting deformation of asphalt pavement. However, the low grade of asphalt and the poor low-temperature performance and fatigue life of the mixture can easily lead to the low-temperature cracking [...] Read more.

High asphalt grade and poor high-temperature performance are the primary reasons for the permanent rutting deformation of asphalt pavement. However, the low grade of asphalt and the poor low-temperature performance and fatigue life of the mixture can easily lead to the low-temperature cracking of asphalt pavement. With the rapid increase in road traffic, volume, and traffic load, the performance requirements of road asphalt materials are becoming higher and higher. High-modulus asphalt has excellent temperature stability and good fatigue resistance. However, high-modulus asphalt is expensive, so its use can greatly increase the pavement cost, restricting its wide application in road engineering. It is necessary to find an economical way to produce modified asphalt to meet the current road requirements. The aim of this study is to investigate the effects of styrene-butadiene-styrene block copolymer (SBS) and rock asphalt on the road performance of modified high-modulus asphalt, in which the replacement level of SBS and rock asphalt below 8 wt.% are compared. Apart from the conventional performance measurements, such as softening point, penetration, ductility and viscosity, thermal storage stability and rheological properties are also measured. The test results show that the composite modification of SBS and North American rock asphalt can effectively improve the high-temperature resistance and reduce the temperature sensitivity of 50# matrix asphalt, but it has no obvious improvement on its low-temperature performance. The preferred ternary blending system containing 4~6 wt.% SBS and 6~8 wt.% rock asphalt was obtained by performance analysis. It was verified that the performances of high-modulus asphalt mixture with the ternary blending asphalt above all meet the requirements of high-modulus asphalt mixture performance index. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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13 pages, 8168 KiB

Open AccessArticle

Mechanical Response Analysis of Asphalt Pavement Structure with Embedded Sensor

by Pengcheng Wang, Guoqiang Zhong, Xue Xin, Fei Xiao, Ming Liang, Chao Wang, Yuepeng Jiao, Yanli Zhu, Shang Liu and Hao Wang

Coatings 2022, 12(11), 1728; https://doi.org/10.3390/coatings12111728 - 12 Nov 2022

Cited by 1 | Viewed by 1589

Abstract

Long-term and real-time monitoring of asphalt pavement can be carried out by using embedded sensors to perceive and predict structural damage during pavement operation period, so as to avoid sustained development of damage. However, the influence of embedded sensors on the mechanical properties [...] Read more.

Long-term and real-time monitoring of asphalt pavement can be carried out by using embedded sensors to perceive and predict structural damage during pavement operation period, so as to avoid sustained development of damage. However, the influence of embedded sensors on the mechanical properties of asphalt pavement structure and the structural optimization of sensing elements needs to be further studied. Based on the finite element numerical simulation method, static load model and three-point bending test mode were conducted with three “pavement-sensor” coupling model without sensor, with embedded I-shape sensor, with embedded corrugated-shape sensor. Three simulated conditions were studied comparatively of the sensing element embedding effect on the mechanical response of asphalt pavement structure. Results show that the sensing elements embedded with the two structures have a certain influence on the stress and strain field of asphalt concrete. Within the range of 60–100 mm the asphalt mixture is in a state of tension; the stress values increase with depth and show a maximum tensile stress state at the bottom of the beam. In the compression zone, the strain of the I-shape sensing element embedded is closer to that of the strain without the sensing element embedded. Along the axis of the two sensing elements, the axial strain of the I-shape sensing element is smoother and uniform, which ensures the deformation coordination in the road state. The optimal length L of the sensing element is 14 cm, the diameter φ of the sensor is 10 mm, and the I-beam length GL is 10 cm. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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13 pages, 3254 KiB

Open AccessArticle

Aggregate Gradation Variation on the Properties of Asphalt Mixtures

by Yanchao Yue, Moustafa Abdelsalam and M. S. Eisa

Coatings 2022, 12(11), 1608; https://doi.org/10.3390/coatings12111608 - 22 Oct 2022

Cited by 5 | Viewed by 2292

Abstract

National highway projects present a crucial role in economic growth, as they have a great influence on the national income. Therefore, the decision makers plan to construct these projects at a rapid rate. To achieve the just aforesaid, the utilization of asphalt of [...] Read more.

National highway projects present a crucial role in economic growth, as they have a great influence on the national income. Therefore, the decision makers plan to construct these projects at a rapid rate. To achieve the just aforesaid, the utilization of asphalt of adequate quality and gradation is essential. The key problem which lies in recent decades is that many types of asphalt mixtures are rejected and reconstructed in the site due to the gradation variation of aggregates in the asphalt mixture which waste raw materials, cost and time. Thus, this research seeks to assess the possibility of accepting asphalt mixes with aggregates gradation variation (within the range from +4% above the upper specification limit to −2% below the lower specification limit). A wearing surface mix with gradation 3B was prepared according to the Egyptian code. The gradation variation was presented as the aggregate gradation is out of the specification limits during Hot Mix Asphalt (HMA) production. The aggregate gradations lie above and below the upper and lower specification limits, respectively, by ±2%, ±4% and ±6%. The design gradation of the control mix was included as a reference case. The different mix properties were measured using the Marshall Mix design method. Then, the performance of HMA mixes was evaluated under the effects of high temperature and water cycles through applying wheel loading tracking and Indirect Tensile Strength (ITS) tests. The results show that the 3B mixes with a gradation within a range of +4% to −2% of the upper and lower specification limits recorded the lowest rutting depth and the highest water damage resistance in hot regions compared to ordinary asphalt mixes. In summary, the new aggregate gradation limits will provide a reference for the design of asphalt mixture in hot climate regions. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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12 pages, 1621 KiB

Open AccessArticle

A High Proportion Reuse of RAP in Plant-Mixed Cold Recycling Technology and Its Benefits Analysis

by Yanan Li, Yuzhen Zhang and Shucai Zhang

Coatings 2022, 12(9), 1283; https://doi.org/10.3390/coatings12091283 - 2 Sep 2022

Cited by 2 | Viewed by 1926

Abstract

The concept of the “no-waste city” has focused increasing attention on the recycling of solid waste. One such waste is reclaimed asphalt pavement (RAP), which is generated during road maintenance. The potential to reuse this resource has attracted extensive attention in recent years. [...] Read more.

The concept of the “no-waste city” has focused increasing attention on the recycling of solid waste. One such waste is reclaimed asphalt pavement (RAP), which is generated during road maintenance. The potential to reuse this resource has attracted extensive attention in recent years. This paper explores this concept via a case study of the reconstruction of two sections of the Beijing-Taipei Expressway (from Bengbu to Hefei, sections K69–K69 + 500 and K69 + 500–K69 + 900). The upper base layer of one section was paved with a novel mixture of emulsified asphalt, mixed with a high proportion of RAP made using plant-mixed cold recycling technology (EAPM-HP_RAP). For comparison, the upper base layer of the other section was paved with a conventional large-stone porous asphalt mix (LSPM). The proportions of the components of EAPM-HP_RAP were optimized via laboratory-based proportioning design followed by proportioning verification. The results showed that the high-temperature stability, water damage resistance and pavement strength of the EAPM-HP_RAP met the specifications of relevant engineering standards. Next, the economic and environmental benefits of this novel approach were estimated. The approach was estimated to save CNY (China Yuan) 1.5–1.8 million in engineering costs per km of road (roadbed width = 27.5 m) and CNY 158–189 million for the whole project (105 km in length). It was also estimated to reduce energy consumption equivalent to 67.41 tons of standard coal per km. Further calculations showed that every km of pavement could reduce CO₂ emissions by 176.6 tons, SO₂ emissions by 0.6 tons, NO_X emissions by 0.5 tons, ash emissions by 17.6 tons and soot emissions by 1.0 tons compared with conventional methods. For the whole road section, this is equivalent to reducing CO₂ emissions by 18,543 tons, SO₂ emissions by 60.2 tons, NO_X emissions by 52.5 tons, ash emissions by 1848 tons, and soot emissions by nearly 105 tons. In summary, it is feasible for EAPM-HP_RAP to be used as the upper base layer in highway renovation projects. It reduces the need to mine new ores and allocate land to RAP storage, which is associated with soil and water pollution due to chemical leaching from aged asphalt. This approach provides great economic and environmental benefits compared with the use of conventional pavement technology. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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23 pages, 13282 KiB

Open AccessArticle

Decision-Making for Typical Pavement Structure Based on Life-Cycle Economic Evaluation and Key Performance Indicators

by Ming Zhang, Chong Wang, Lulu Fan and Junyan Yi

Coatings 2022, 12(8), 1124; https://doi.org/10.3390/coatings12081124 - 5 Aug 2022

Viewed by 1464

Abstract

The economy and rationality of the typical structural scheme for asphalt pavement are directly related to the formation of its service target. Based on the original highway asphalt pavement structure in Jilin Province, the evaluation index system was established by the research of [...] Read more.

The economy and rationality of the typical structural scheme for asphalt pavement are directly related to the formation of its service target. Based on the original highway asphalt pavement structure in Jilin Province, the evaluation index system was established by the research of the literature, investigation and Delphi method, and the results of expert consultation were tested by indicators such as enthusiasm, authority and coordination. The Kendall coordination coefficient was 0.803, indicating a strong degree of evaluation consistency. Then, using the finite element method and pavement economic analysis method, the key parameters of pavement structure asphalt, pavement design performance and economy are calculated. Finally, the key indicators in the pavement design process are quantified by using analytic hierarchy process (AHP) and gray relational theory, the weight of each key indicator and the correlation degree of the pavement structure are calculated, and pavement structure 1 is determined to be the best solution. The results show that a decision model for typical structural types of asphalt pavement can be established by using an improved gray relational analytic hierarchy process. In this study, the decision-making model can quickly and conveniently determine the most suitable typical pavement structure, the selected structures are checked, and the calculation results meet the requirements of the specification. However, given the limited reference cases, the proposed pavement structure decision-making method needs to be verified and improved through more practical applications. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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18 pages, 6316 KiB

Open AccessArticle

Performance and Simulation Study of Aged Asphalt Regenerated from Waste Engine Oil

by Fan Zhang, Haibin Li, Xiaolong Zou, Canyang Cui, Yaping Shi, Hongwei Wang and Fayong Yang

Coatings 2022, 12(8), 1121; https://doi.org/10.3390/coatings12081121 - 5 Aug 2022

Cited by 4 | Viewed by 1907

Abstract

In order to reuse waste resources (waste engine oil and waste asphalt mixture), the regeneration process of waste oil on aged asphalt is systematically explained. The BA was treated by aging test, and the basic mechanical properties, molecular dynamics simulation, and infrared spectrum [...] Read more.

In order to reuse waste resources (waste engine oil and waste asphalt mixture), the regeneration process of waste oil on aged asphalt is systematically explained. The BA was treated by aging test, and the basic mechanical properties, molecular dynamics simulation, and infrared spectrum test were carried out on this basis. The results showed that the WEO can restore the physical properties of the aged asphalt, and the recommended amount of WEO is 3%. The density of the asphalt model corresponds to the actual situation of the asphalt. The aged asphalt components are more aggregated. After the WEO was added, the components of asphalt aggregation were reduced and the diffusion ability was improved. Finally, infrared spectroscopy tests were conducted on asphalt specimens, and the results showed that the process of rejuvenated asphalt was dominated by physical reactions. Consequentially, the results of this study build a bridge between the performance and simulation of aged asphalt rejuvenated by WEO. Consequentially, the results of this research promote the recycling of WEO and waste asphalt pavement materials, ultimately advocating the sustainability of pavement construction. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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16 pages, 5141 KiB

Open AccessArticle

Mechanical and Self-Healing Performance of Yellow River Alluvial Silt Treated with Composite Flexible Curing Agent

by Zhiyi Sai, Lin Wang, Hongchao Han, Wenjuan Wu, Zhaoyun Sun, Jincheng Wei, Lei Zhang, Guiling Hu and Hao Wu

Coatings 2022, 12(6), 870; https://doi.org/10.3390/coatings12060870 - 20 Jun 2022

Cited by 2 | Viewed by 1706

Abstract

The silt in the Yellow River alluvial plain has low clay content, low cohesion and poor structure. Its stability has always been a difficult problem in the engineering field. In order to improve the engineering properties of the silt in the alluvial plain [...] Read more.

The silt in the Yellow River alluvial plain has low clay content, low cohesion and poor structure. Its stability has always been a difficult problem in the engineering field. In order to improve the engineering properties of the silt in the alluvial plain of the Yellow River, a new type of silt composite flexible curing agent was prepared by using sintered red mud and matrix asphalt as the main materials to comprehensively stabilize the silt. The aim of this study was to investigate the effects of sintered red mud-asphalt composite flexible curing agent on aged mechanical properties of treated silt, in which the replacement levels of the flexible curing agent below 10% by weight are compared. Apart from the compressive strength, the drying shrinkage, low temperature freeze-thaw and high temperature self-healing ability are measured. The test results show that the flexible curing agent has a positive effect on improving the mechanical properties of stabilized silt. The flexible curing agent series exhibit higher compressive strength, better water stability, resistance to freeze-thaw and high temperature self-healing ability, and lower drying shrinkage compared to silt and cement stabilized silt. The preferred dosage 4%~6% of the flexible curing agent is obtained by mechanical property analysis. The SEM images show that the incorporation of the flexible curing agent helps the silt form dense cementation and non-connected microporous structure, that is beneficial to the improvement of water stability and frost resistance. The asphalt component in the flexible curing agent can reorganize and diffuse in the soil, fill the internal pores and micro cracks, and realize the repair of soil damage and structural reinforcement. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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13 pages, 3135 KiB

Open AccessArticle

Influence of Frequent Freeze–Thaw Cycles on Performance of Asphalt Pavement in High-Cold and High-Altitude Areas

by Haibo Cao, Tuanjie Chen, Hongzhou Zhu and Haisheng Ren

Coatings 2022, 12(6), 752; https://doi.org/10.3390/coatings12060752 - 31 May 2022

Cited by 9 | Viewed by 2127

Abstract

This study explores the temperature changes and freeze–thaw cycles in certain typical high-altitude areas, finding that these areas encounter more than 120, or even more than 200, freeze–thaw cycles per year. Such frequent freeze–thaw cycles deliver significant impact on the performance of asphalt [...] Read more.

This study explores the temperature changes and freeze–thaw cycles in certain typical high-altitude areas, finding that these areas encounter more than 120, or even more than 200, freeze–thaw cycles per year. Such frequent freeze–thaw cycles deliver significant impact on the performance of asphalt pavements, with cracks becoming a typical problem in high-altitude areas. Such factors as cold weather, large temperature differences, and frequent freeze–thaw cycles have adverse effects on the stress of asphalt pavement materials, resulting in cracks in pavements. By simulating the conditions of such frequent freeze–thaw cycles, this study explores the law of changes in the performance of roads made from asphalt and asphalt mixtures, as well as the low-temperature crack resistance properties of asphalt and asphalt mixtures in frequent freeze–thaw cycles. It is found that the performance of the three different types of asphalt binders used in the test shows basically no change after 50 freeze–thaw cycles, and the asphalt types have a significant effect on the low-temperature performance of asphalt mixtures. The modified asphalt shows a higher viscosity than the matrix asphalt, with better toughness than that of the matrix asphalt at low temperature. Frequent freeze–thaw cycles significantly influence the low-temperature splitting tensile strength and water stability of asphalt mixtures; with increased freeze–thaw cycles, the splitting strength and freeze–thaw splitting tensile strength ratio will gradually decrease to a significant level. The freeze–thaw conditions are found delivering remarkable influence on the low-temperature splitting tensile strength and water stability of asphalt mixtures. The research results of this study provide a basis for the selection of asphalt pavement materials as well as the optimal design of mixtures in high-altitude area like the Qinghai-Tibet Plateau. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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14 pages, 3518 KiB

Open AccessArticle

Effect of Fine Aggregate Gradation on Macro and Micro Properties of Cold Recycling Mixture Using Emulsified Asphalt

by Zhigang Li, Kexin Li, Jianmin Zhang, Ruibo Ren, Pinru Du, Pinhui Zhao, Quanman Zhao and Litao Geng

Coatings 2022, 12(5), 674; https://doi.org/10.3390/coatings12050674 - 14 May 2022

Cited by 2 | Viewed by 1835

Abstract

In order to explore the influence of fine aggregate on the macro and micro properties of cold recycling mixture using emulsified asphalt (CRME), mechanical and microscopic property tests were carried out. The indirect tensile strength (ITS), unconfined compressive strength (UCS) and triaxial shear [...] Read more.

In order to explore the influence of fine aggregate on the macro and micro properties of cold recycling mixture using emulsified asphalt (CRME), mechanical and microscopic property tests were carried out. The indirect tensile strength (ITS), unconfined compressive strength (UCS) and triaxial shear strength of different fine aggregate gradation was measured for analyzing the effects of fine aggregate on the mechanical strength, triaxial shear resistance and fracture energy of CRME. Meanwhile, the surface morphologies and air voids distribution of different CRME were observed by scanning electron microscopy (SEM) and X-ray computed tomography (X-ray CT). The results show that fine aggregate has a significant effect on the mechanical strength and shear resistance of CRME. With the same water and asphalt content, the fracture energy and failure strain of the mixture with less fine aggregate (G3-2) decreased by 16.2% and 18.2%, respectively. The less content of powder there was, the fewer cement hydration products there were due to some cement being coated by emulsified asphalt and the “cement hydration products fiber” length being shorter. Approximately 70% of the AFt hydration products in the G3-2 mixture were in the range of 1–4 μm, while those in the G1 mixture were in the range of 4–8 μm. With the increase in filler content, the number of air voids in the volume range of 0.5 mm³ ≤ V < 5 mm³ in CRME decreased, and the number of air voids in the volume range of V < 0.5 mm³ significantly increased, while the equivalent radius of air voids decreased slightly with the increase in filler content. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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18 pages, 5947 KiB

Open AccessArticle

Effect of Solid-Solid Phase Change Material’s Direct Interaction on Physical and Rheological Properties of Asphalt

by Haisheng Zhao, Jianmin Guo, Shijie Ma, Huan Zhang, Chunhua Su, Xiaoyan Wang, Zengguang Li, Jincheng Wei and Shiping Cui

Coatings 2022, 12(5), 625; https://doi.org/10.3390/coatings12050625 - 3 May 2022

Cited by 6 | Viewed by 1680

Abstract

Asphalt pavement is a temperature−sensitive structure that is prone to temperature-related diseases. Phase change material (PCM) is an excellent candidate for mitigating these diseases. This paper looked into the effects of indirect composite shape-stabilized PCM incorporation on the characteristics of asphalt. The compatibility, [...] Read more.

Asphalt pavement is a temperature−sensitive structure that is prone to temperature-related diseases. Phase change material (PCM) is an excellent candidate for mitigating these diseases. This paper looked into the effects of indirect composite shape-stabilized PCM incorporation on the characteristics of asphalt. The compatibility, physical properties, and rheological properties of asphalt with various PCM content before and after aging were thoroughly investigated. No phase separation and no chemical reaction occurred between PCM and asphalt. The physical properties improved with the addition of PCM, and the high−temperature performance indexes improved while the low−temperature performance indexes decreased as the aging process progressed. The effects of PCM on the rheological properties of the matrix and SBS−modified asphalt was distinct. PCM was added to improve the high−temperature rheological characteristics of the matrix asphalt when the temperature was higher than 52 °C, while PCM reduced the high−temperature rheological properties of the SBS−modified asphalt. The aging process has an impact on the high−temperature rutting factor of asphalt with a high PCM content. The low−temperature creep behavior and PG grade of asphalt were both improved. The implication of PCM is that it cannot increase the thermoregulation of asphalt pavement without the cost of scarifying the performance of the asphalt or mixture. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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18 pages, 6005 KiB

Open AccessArticle

Research on the Preparation of Graphene Quantum Dots/SBS Composite-Modified Asphalt and Its Application Performance

by Youfu Lu, Nan Shi, Mingming Wang, Xinyang Wang, Liyang Yin, Qiang Xu and Pinhui Zhao

Coatings 2022, 12(4), 515; https://doi.org/10.3390/coatings12040515 - 11 Apr 2022

Cited by 9 | Viewed by 1915

Abstract

This study aims to prepare a graphene quantum dots (GQDs)/styrene-butadiene segmented copolymer composite (GQDs/SBS) as an asphalt modifier using the Pickering emulsion polymerization method. The physicochemical properties of the GQDs/SBS modifier and their effects on asphalt modification were investigated. In addition, the GQDs/SBS [...] Read more.

This study aims to prepare a graphene quantum dots (GQDs)/styrene-butadiene segmented copolymer composite (GQDs/SBS) as an asphalt modifier using the Pickering emulsion polymerization method. The physicochemical properties of the GQDs/SBS modifier and their effects on asphalt modification were investigated. In addition, the GQDs/SBS modifier was compared with the pure SBS modifier. Research results demonstrated that GQDs could be evenly dispersed into the SBS phase to form a uniform composite. Adding GQDs brings more oxygen-containing functional groups into the GQDs/SBS modifier, thus strengthening the polarity and making it disperse into the asphalt better. Compared with the SBS modifier, the GQDs/SBS modifier presents better thermostability. Moreover, GQDs/SBS composite-modified asphalt achieves better high-temperature performance than SBS-modified asphalt, which is manifested by the increased softening points, complex shear modulus and rutting factors. However, the low-temperature performance decreases, which is manifested by reductions in cone penetration, viscosity and ductility as well as the increased ratio between creep stiffness (S) and creep rate (m), that is, S/m. Furthermore, adding GQDs can improve the high-temperature performance of asphalt mixture, but it influences low-temperature and water stability slightly. GQDs/SBS also have the advantages of simple preparation techniques, low cost and are environmentally friendly. Therefore, they have become a beneficial choice as asphalt cementing material modifiers. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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10 pages, 3231 KiB

Open AccessArticle

The Direct and Oblique Shear Bond Strength of Geogrid-Reinforced Asphalt

by Qiaoyi Li, Guangqing Yang, He Wang and Zhijie Yue

Coatings 2022, 12(4), 514; https://doi.org/10.3390/coatings12040514 - 11 Apr 2022

Cited by 3 | Viewed by 1582

Abstract

The interlayer bonding strength is an essential property of geogrid-reinforced asphalt. To study the interlayer bonding characteristics of geogrid-reinforced asphalt, direct shear and oblique shear tests were carried out in the laboratory. The direct interlaminar shear strength of geogrid-reinforced asphalt was lower than [...] Read more.

The interlayer bonding strength is an essential property of geogrid-reinforced asphalt. To study the interlayer bonding characteristics of geogrid-reinforced asphalt, direct shear and oblique shear tests were carried out in the laboratory. The direct interlaminar shear strength of geogrid-reinforced asphalt was lower than that of unreinforced asphalt. The oblique shear strength of the carbon–carbon geogrid-reinforced sample was the highest, the unreinforced sample was second, and the carbon–glass geogrid-reinforced sample was the lowest. The stiffness of the geogrid affects the oblique shear strength. The interlayer direct shear strengths of AC-20C asphalt samples were higher than AC-13C asphalt samples. The oblique shear strengths of AC-20C asphalt samples were almost the same as the AC-13C asphalt samples. Normal stress made the double-layered sample tend to behave as a homogeneous granular material. The direct shear strength vs. shear displacement curves showed an area of oscillation, but the oblique shear curves were smooth throughout the process. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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26 pages, 10162 KiB

Open AccessArticle

Preparation and Temperature Susceptibility Evaluation of Crumb Rubber Modified Asphalt Applied in Alpine Regions

by Youjie Zong, Rui Xiong, Yaogang Tian, Mingfeng Chang, Xiaowen Wang, Jiahao Yu, Yixing Zhang, Baozhu Feng, Haoyu Wang and Chuang Li

Coatings 2022, 12(4), 496; https://doi.org/10.3390/coatings12040496 - 7 Apr 2022

Cited by 8 | Viewed by 2020

Abstract

In alpine regions, the durability of asphalt pavement is worse due to the harsh climate. However, crumb rubber modified asphalt has the potential to improve the durability of pavement. Based on matrix asphalt, crumb rubber, Trans-Polyoctenamer Rubber Reactive Modifier (TOR), and an orthogonal [...] Read more.

In alpine regions, the durability of asphalt pavement is worse due to the harsh climate. However, crumb rubber modified asphalt has the potential to improve the durability of pavement. Based on matrix asphalt, crumb rubber, Trans-Polyoctenamer Rubber Reactive Modifier (TOR), and an orthogonal test, the preparation scheme of crumb rubber modified asphalt suitable for alpine regions was obtained. The crumb rubber was selected 30 mesh, and the content of crumb rubber was 24% of the quality of matrix asphalt. Shearing time was 60 min, and preparation temperature was 205 °C. Shearing rate was 5000 r/min, and optimum TOR content was set as 4.5% of the quality of crumb rubber. The temperature susceptibility of matrix asphalt (JZ), crumb rubber modified asphalt (AR), crumb rubber modified asphalt mixed with TOR (TAR) was investigated. The high temperature performance indexes, including phase angle, the complex modulus index, and rutting factor, and the low temperature performance indexes including creep rate and stiffness modulus, the ratio of creep rate and stiffness modulus, Burgers model parameters, dissipated energy ratio, and the derivative of creep compliance were analyzed in depth with multiple parameters. Meanwhile, the mechanisms of prepared AR and TAR were explored. The results indicate that the PG grading is PG64-22 of JZ, PG70-34 of AR, and PG82-28 of TAR. The deformation resistance of TAR at high temperature is superior to AR. The addition of crumb rubber not only improves the temperature susceptibility, but also enhances its viscoelasticity at low temperatures. After the crumb rubber swell in the asphalt system, the network structures are crosslinked and the physical and chemical effects are produced, such as cracking and repolymerization in the asphalt system. TOR can further enhance the swelling and network crosslinking effects of rubber-asphalt. The TAR has the strongest weather resistance. The study provides guidance for AR and TAR to be used in alpine regions. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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14 pages, 9108 KiB

Open AccessArticle

Investigation of Tri-Axial Stress Sensing and Measuring Technology for Tire-Pavement Contact Surface

by Jiaxi Guan, Xinglin Zhou, Lu Liu, Maoping Ran and Yuan Yan

Coatings 2022, 12(4), 491; https://doi.org/10.3390/coatings12040491 - 6 Apr 2022

Cited by 3 | Viewed by 1874

Abstract

A tri-axial stress sensor was designed to measure contact stresses in the tire–pavement contact patch. The shape and size of the sensor surface were designed considering both the asphalt pavement texture and the tire pattern. The top-down cracking mechanism was also taken into [...] Read more.

A tri-axial stress sensor was designed to measure contact stresses in the tire–pavement contact patch. The shape and size of the sensor surface were designed considering both the asphalt pavement texture and the tire pattern. The top-down cracking mechanism was also taken into account, and the sensor was placed at the vertical crack depth. Temperature drifts and zero drifts were compensated for. The sensor had high structural strength and met the sensing requirements of specialized heavy vehicles. In a preliminary study, three sensors were fabricated and calibrated in three directions. Simulated measurements were performed using a tire–pavement surface contact test bench. Signals from the L-shaped sensor region were obtained for the upper, middle, and lower parts of the tire, and preliminary stress distributions were determined at different positions on the contact surface. This study has laid a foundation for the design and construction of a more precise test system in the future. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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13 pages, 2939 KiB

Open AccessArticle

Utilization of Modified Red Mud Waste from the Bayer Process as Subgrade and Its Performance Assessment in a Large-Sale Application

by Shijie Ma, Zhaoyun Sun, Jincheng Wei, Xiaomeng Zhang and Lei Zhang

Coatings 2022, 12(4), 471; https://doi.org/10.3390/coatings12040471 - 30 Mar 2022

Cited by 9 | Viewed by 2597

Abstract

The utilization of red mud waste discharged from the Bayer production process used for extracting alumina from bauxite presents a pressing demand in the aluminum industry. This study aims to adopt a chemical modifier to solidify the Bayer red mud for its application [...] Read more.

The utilization of red mud waste discharged from the Bayer production process used for extracting alumina from bauxite presents a pressing demand in the aluminum industry. This study aims to adopt a chemical modifier to solidify the Bayer red mud for its application in highway subgrade. The mechanism and properties of the modified red mud using a modifier composed of cement, phosphogypsum and organic polymer, were analyzed and investigated. It was found that the optimal modifier dosage of the solidified modifier was 8%. The three-day unconfined compressive strength of the modified Bayer red mud could reach up to 3 MPa and its strength loss when immersed in water at 7 days and 28 days measured less than 20%. For its real application as subgrade, its road performance could be achieved with good bearing capacity, including a resilient modulus value greater than 90 MPa, a dynamic deformation modulus reaching up to 140 MPa and the Falling Weight Deflectometer (FWD) value measuring less than 100 (0.01 mm). Compared with traditional lime or cement stabilized soil, using locally modified Bayer red mud for subgrade filling can reduce the project cost, minimize the consumption of non-renewable resources and reduce the emission of environmental hazards, thus providing an engineering reference for large-scale and resource-based road applications. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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16 pages, 2083 KiB

Open AccessArticle

Properties of SBS/MCF-Modified Asphalts Mixtures Used for Ultra-Thin Overlays

by Quanman Zhao, Xiaojin Lu, Shuo Jing, Yao Liu, Wenjun Hu, Manman Su, Peng Wang, Jifa Liu, Min Sun and Zhigang Li

Coatings 2022, 12(4), 432; https://doi.org/10.3390/coatings12040432 - 23 Mar 2022

Cited by 7 | Viewed by 1966

Abstract

In order to produce high-viscosity and high-toughness asphalt for ultra-thin overlays, the conventional asphalt cement was modified with high-content SBS and micro carbon fiber (MCF). The performances of the modified asphalt were studied by tests of penetration, softening point, ductility, kinematic viscosity, multiple [...] Read more.

In order to produce high-viscosity and high-toughness asphalt for ultra-thin overlays, the conventional asphalt cement was modified with high-content SBS and micro carbon fiber (MCF). The performances of the modified asphalt were studied by tests of penetration, softening point, ductility, kinematic viscosity, multiple stress creep recovery (MSCR), and by dynamic shear rheometer (DSR) and bending beam rheometer (BBR). Mixture properties were studied by tests of rutting, low-temperature bending, freeze–thaw splitting, four-point bending fatigue and dynamic modulus. The results reflect that the addition of MCF could enormously improve the high- and low-temperature properties, increase the viscosity of asphalt, and improve the toughness of asphalt. When SBS content was 6%, with the increase of MCF content, G*/sin δ and R values first increased and then decreased, and the J_nr value first decreased and then increased. When MCF content was 0.8%, the overall performance was best. Adding MCF into an asphalt mixture or increasing the content of SBS improved the rutting resistance, low-temperature crack resistance, water stability, and fatigue performance of the asphalt mixture. At the same temperature and frequency, there was little difference in phase angle between the 6%SBS + 0.8%MCF and 5%SBS + 0.0%MCF modified asphalt mixtures, and the dynamic modulus was slightly higher over the whole range. It can be concluded that the addition of SBS and MCF can enormously enhance the viscosity and toughness of asphalt. The viscosity of the 6%SBS + 0.8%MCF modified asphalt met the performance requirements of high-viscosity asphalt. When used for ultra-thin overlays, it had great road service performance and met the application requirements. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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18 pages, 5292 KiB

Open AccessArticle

Interlaminar Shear Characteristics, Energy Consumption, and Carbon Emissions of Polyurethane Mixtures

by Yufeng Bi, Min Sun, Shuo Jing, Derui Hou, Wei Zhuang, Sai Chen, Xuwang Jiao and Quanman Zhao

Coatings 2022, 12(3), 400; https://doi.org/10.3390/coatings12030400 - 17 Mar 2022

Cited by 3 | Viewed by 2389

Abstract

The interlaminar shear characteristics of a polyurethane (PU) mixture composite structure, quantitatively calculating its energy consumption and carbon emissions were analyzed in this study. Inclined shear tests were carried out on thirteen structures without interlaminar treatment, and high-temperature water bath accelerated loading tests [...] Read more.

The interlaminar shear characteristics of a polyurethane (PU) mixture composite structure, quantitatively calculating its energy consumption and carbon emissions were analyzed in this study. Inclined shear tests were carried out on thirteen structures without interlaminar treatment, and high-temperature water bath accelerated loading tests were conducted on three composite structures; further, the interlaminar shear strength of the tire trace position after the accelerated loading test was tested to analyze the influence of both the high-temperature water bath environment and loading on the structure. In addition, based on the medium repair project of the Qingdao-Yinchuan expressway, the construction log of PU mixture pavement and asphalt pavement was investigated. Combined with the calculation parameters provided by the United Nations Intergovernmental Panel on Climate Change (IPCC), the consumption and carbon emissions of the two types of mixtures were calculated and compared quantitatively. The results showed that the shear strength between layers of asphalt mixtures, PU mixture and asphalt mixture was less than 2 MPa; however, the shear strength between PU mixture–cement-stabilized macadam and PU mixture–PU mixture was greater than 3 MPa. Therefore, it was recommended to spread a 0.4 L/m² two-component PU adhesive layer as the interlayer treatment scheme for the structure of asphalt mixture-PU mixture and PU mixture-asphalt mixture; the high-temperature water area and accelerated loading had different effects on the interlaminar shear strength of the three structures. The PUM-16 mixture could effectively reduce energy consumption by 88.3 and 87.2%, carbon emissions by 81.1% and 79.1% in comparison to Stone Matrix asphalt with Nominal maximum particle size of 13.2 mm (SMA-13) and Stone Matrix asphalt with Nominal maximum particle size of 19.0 mm (SMA-20). Thus, the PU mixture was confirmed to be an environmentally friendly road pavement material. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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16 pages, 5990 KiB

Open AccessArticle

Research on the Quality of Asphalt Pavement Construction Based on Nondestructive Testing Technology

by Wei Chen, Guiling Hu, Wenyang Han, Xiaomeng Zhang, Jincheng Wei, Xizhong Xu and Xiangpeng Yan

Coatings 2022, 12(3), 379; https://doi.org/10.3390/coatings12030379 - 14 Mar 2022

Cited by 6 | Viewed by 2573

Abstract

In order to better evaluate the construction quality of asphalt pavement, nondestructive testing techniques are used to inspect newly paved asphalt mixture pavement. The proposed system for the evaluation of asphalt pavement construction quality uses three-dimensional ground-penetrating radar (GPR) and a non-nuclear density [...] Read more.

In order to better evaluate the construction quality of asphalt pavement, nondestructive testing techniques are used to inspect newly paved asphalt mixture pavement. The proposed system for the evaluation of asphalt pavement construction quality uses three-dimensional ground-penetrating radar (GPR) and a non-nuclear density gauge. The GPR and the non-nuclear density gauge test results were used to establish a dielectric constant–porosity model by fitting. This approach can more accurately determine the dielectric constant selection scheme of the GPR based on the average value of every 10 dielectric constant data points in the length direction of the radar antenna and every three data channels in the width direction. The GPR collected the dielectric constants of the road surface based on the total reflection method and used the average value of the local dielectric constant to evaluate the construction quality of the road. The non-nuclear density gauge used the local porosity to assess the construction quality of the road. It is recommended that the two testing schemes described above be used to evaluate the quality of asphalt pavement construction. They can provide theoretical guidance for future applications in practical processes. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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17 pages, 72717 KiB

Open AccessArticle

Properties of Different Waterproof Bonding Layer Systems for Cement Concrete Bridge Deck Pavement

by Jiancun Fu, Aiqin Shen and Zhaodi Yuan

Coatings 2022, 12(3), 308; https://doi.org/10.3390/coatings12030308 - 24 Feb 2022

Cited by 6 | Viewed by 2809

Abstract

The performance of waterproof bonding layer systems significantly affects the service life of concrete bridge deck pavement. This article aims to compare the bonding properties and composite structure mechanical properties of different waterproof bonding layer systems in bridge deck pavement to recommend appropriate [...] Read more.

The performance of waterproof bonding layer systems significantly affects the service life of concrete bridge deck pavement. This article aims to compare the bonding properties and composite structure mechanical properties of different waterproof bonding layer systems in bridge deck pavement to recommend appropriate structures based on service conditions. To fulfill this objective, four kinds of waterproof bonding material composite systems were designed, and test samples were fabricated. Then, the waterproof bonding layer properties were studied by penetration resistance tests, scalding resistance tests, and corrosion resistance tests. Pull-off tests were conducted to compare the bonding properties. Then, dynamic modulus tests, Hamburg wheel tracking tests, and static load creep tests of composite structure specimens were implemented to evaluate the dynamic and static mechanical performances and water-temperature stability. The findings showed that the four schemes had good impermeability. The pull-off strengths of scheme III at 25 °C were about 2.5-, 2.5-, and 4-times those of schemes I, II, and IV, respectively, and the pull-off strengths at 50 °C were about 1.6-, 2-, and 1.6-times those of schemes I, II, and IV, respectively, and the bonding performances and dynamic modulus of different schemes were ranked as follows: III > I > II > IV. The results of the Hamburg wheel tracking test were consistent with the static load creep test. The high-temperature stability of scheme IV was the best, while the stabilities of scheme III and I were better than that of scheme II. In conclusion, the scheme of concrete bridge deck pavement can be selected based on the environmental conditions and traffic load, and schemes III and I should be considered first. The findings of this research could provide technical support for the future design of bridge deck waterproof bonding systems. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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16 pages, 3051 KiB

Open AccessArticle

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

by Guodong Zeng, Wenjuan Wu, Juechi Li, Qinsheng Xu, Xianghang Li, Xiangpeng Yan, Ye Han and Jincheng Wei

Coatings 2022, 12(2), 270; https://doi.org/10.3390/coatings12020270 - 17 Feb 2022

Cited by 9 | Viewed by 2067

Abstract

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 [...] Read more.

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. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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15 pages, 3650 KiB

Open AccessArticle

Experimental Study and Performance Characterization of Semi-Flexible Pavements

by Guosheng Li, Huan Xiong, Qi Ren, Xiaoguang Zheng and Libao Wu

Coatings 2022, 12(2), 241; https://doi.org/10.3390/coatings12020241 - 13 Feb 2022

Cited by 7 | Viewed by 2105

Abstract

Semi-flexible pavement (SFP) is made up of a porous skeleton of asphalt mixture and cement grout. This special structure granted SFP superior strength and durability and made it a promising solution for the paving of heavy trafficked area. This paper performed in-depth study [...] Read more.

Semi-flexible pavement (SFP) is made up of a porous skeleton of asphalt mixture and cement grout. This special structure granted SFP superior strength and durability and made it a promising solution for the paving of heavy trafficked area. This paper performed in-depth study on the mechanistic behavior of SFP. Firstly, the volumetric mix design of SFP was introduced, and followed with strength, moisture susceptibility, viscoelastic behavior, fatigue life as well as rutting resistance through a series of laboratory tests. Marshall stability tests and dynamic stability tests suggested that SFP gained fair strength and rutting resistance from the curing of cement grout. Meanwhile, SFP was found not sensitive to freeze–thaw cycles through indirect tensile tests. In dynamic modulus tests, SFP exhibited significant viscoelastic behaviors. In four-point beam fatigue tests, the average fatigue lives of SFP reached 85.4 k loading repetition under 400 µε level. In Hamburg wheel tracking tests, the ultimate rutting depth of SFP was smaller than 2.5 mm. The viscoelastic behavior and rutting propagation of SFP was characterized with master curve and power function by fitting the test results. SFP was also compared with traditional asphalt mixtures in MMLS3 accelerated tests and its performance turned out to be prevailing. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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18 pages, 41082 KiB

Open AccessArticle

Assessment of Modulus Attenuation of Cement and Lime-Fly Ash Semi-Rigid Road Base Materials

by Luchuan Chen, Sixin Yu, Ying Zhu, Xiaomeng Zhang, Wenjuan Wu, Qiang Sun, Tingting Chen, Xiaoyan Wang and Jincheng Wei

Coatings 2022, 12(2), 216; https://doi.org/10.3390/coatings12020216 - 7 Feb 2022

Viewed by 1678

Abstract

For asphalt pavement structures, semi-rigid road base course has to sustain repeated high-axle load during its service life and the performance of semi-rigid road base materials directly influences the durability of pavement structures. The dynamic compressive resilience modulus of two commonly used semi-rigid [...] Read more.

For asphalt pavement structures, semi-rigid road base course has to sustain repeated high-axle load during its service life and the performance of semi-rigid road base materials directly influences the durability of pavement structures. The dynamic compressive resilience modulus of two commonly used semi-rigid road base materials, cement stabilized aggregates (CSG) and lime-fly ash stabilized aggregates (LFSG) were evaluated at different frequencies using a Universal Testing Machine (UTM). The results showed that LFSG had higher dynamic modulus than that of CSG and the load frequency had less influence on the dynamic modulus of these two semi-rigid road base materials. The four-point bending test was applied to measure the flexural-bending strength and the fatigue life of these two semi-rigid materials. A higher flexural-bending strength of LFSG indicated its better bearing capacity than that of CSG. The fatigue life of LFSG and CSG decreased with the increase of stress–strength ratio and the LFSG performed better in terms of fatigue resistance. The fatigue damage models of CSG and LFSG based on Stress-Life (S-N) curve are established. As per incremental-recursive mechanics, a general modulus degradation model was established and verified by the results of full-scale accelerate loading test. This model cannot only be used to predict the fatigue deterioration of semi-rigid road base materials under different stress levels, but is also able to calculate the current bending elastic modulus based on its initial modulus value. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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16 pages, 4763 KiB

Open AccessArticle

Study on Performance Optimization of Composite Natural Asphalt Modified Gussasphalt Mix

by Huadong Sun, Peng Jiang, Yongling Ding, Laixue Pang, Yinbin Liu, Yafei Wang and Xuhe Shang

Coatings 2022, 12(1), 78; https://doi.org/10.3390/coatings12010078 - 11 Jan 2022

Cited by 5 | Viewed by 2066

Abstract

In order to systematically study and develop a type of gussasphalt (GA) mix with superior performance, namely GA-10; the effect of Qingchuan Rock Asphalt (QRA) and Trinidad Lake asphalt (TLA) on the GA-10 mix was assessed based on the study of composite natural [...] Read more.

In order to systematically study and develop a type of gussasphalt (GA) mix with superior performance, namely GA-10; the effect of Qingchuan Rock Asphalt (QRA) and Trinidad Lake asphalt (TLA) on the GA-10 mix was assessed based on the study of composite natural asphalt modified gussasphalt (CNAMGA) binder. Various analytical tests were used to evaluate the engineering properties, thermal stability and microstructure of CNAMGA mix. The results indicate that the stability of QRA modified binder and TLA modified binder in the normal temperature range and the high temperature range have been improved, and the temperature susceptibility is reduced. The optimal asphalt–aggregate ratio of the GA mix is determined to be 9.7%, which has good high-temperature stability, low-temperature crack resistance and construction workability. The QRA mix has better high-temperature stability than the TLA mix, whereas the low-temperature cracking resistance of the TLA mix is better than that of the QRA mix. The two kinds of GA-10 mix have similar construction workability. The fact that the abundant fine aggregates wrapped in binder fill the coarse aggregates surface contributes to the better adhesion of the GA asphalt concrete. The distribution of aggregate and binder is relatively uniform with fewer pores, and the overall proportion of the binder is greater than that of aggregate. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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17 pages, 1535 KiB

Open AccessArticle

Sustainability Evaluation of Cold In-Place Recycling and Hot Mix Asphalt Pavements: A Case of Qassim, Saudi Arabia

by Fawaz Alharbi, Fahad Alshubrumi, Meshal Almoshaogeh, Husnain Haider, Ahmed Elragi and Sherif Elkholy

Coatings 2022, 12(1), 50; https://doi.org/10.3390/coatings12010050 - 1 Jan 2022

Cited by 7 | Viewed by 2890

Abstract

The construction of conventional hot mix asphalt (HMA) pavements results in a number of economic and environmental issues, such as the cost of new overlays and associated impacts on natural resources. Although the cold recycling with an emulsified asphalt-recycling agent holds certain benefits [...] Read more.

The construction of conventional hot mix asphalt (HMA) pavements results in a number of economic and environmental issues, such as the cost of new overlays and associated impacts on natural resources. Although the cold recycling with an emulsified asphalt-recycling agent holds certain benefits over the HMA, its implementation on different road types, ranging from farm-to-market roads to expressways, is yet contentious due to the need for sophisticated equipment and trained workforce. The present research developed a methodology to evaluate all the three dimensions of sustainability, including economic (construction cost), environmental (natural resource depletion), and social (need for advanced equipment and skilled labor) of various scenarios of RAP and conventional asphalt pavements. The present study evaluated an equivalent thickness of the Cold In-place Recycling (CIR) pavement, which behaves similar to HMA pavement under the influence of different traffic loads. Fifty CIR and HMA scenarios for different traffic volumes and pavement layers thicknesses were developed. Finally, the sustainability of all the scenarios was evaluated for traffic designation in Saudi Arabia using fuzzy-based multicriteria analysis. Ranking of scenarios found CIR as a more sustainable overlay option for the feeders, collectors, main urban streets, expressways, and heavily trafficked highways in industrial areas where ESALs (Equivalent Single Axle Loads) range between 2,000,000 and >31,000,000. Considering the limited availability of advanced equipment and skilled labor for CIR pavements, HMA was found be a more sustainable option for farm-to-market roads with the “very light” traffic class. The methodology will help the pavement managers in decision making regarding the selection of sustainable pavement technologies for different road types in Saudi Arabia and the rest of the world. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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11 pages, 3269 KiB

Open AccessArticle

Development of a Mechanistic Method to Obtain Load Position Strain in Instrumented Pavement

by Guiling Hu, Wenyang Han, Jincheng Wei, Deqing Wang, Xiaomeng Zhang, Wenjun Hu and Wei Chen

Coatings 2022, 12(1), 14; https://doi.org/10.3390/coatings12010014 - 23 Dec 2021

Viewed by 2261

Abstract

To study the in-situ response and performance of asphalt pavement, instrumenting pavement with a variety of sensors has become one of the most important tools in the field or accelerated load facilities. In the dynamic response collection process, engineers are more concerned with [...] Read more.

To study the in-situ response and performance of asphalt pavement, instrumenting pavement with a variety of sensors has become one of the most important tools in the field or accelerated load facilities. In the dynamic response collection process, engineers are more concerned with the load position strain of the pavement structure due to wheel wander. This paper proposes a method to obtain the load position and the strain at the load position when there is no lateral-axis positioning system based on multilayer elastic theory. The test section was paved in the field with installed strain sensors to verify and apply the proposed method. The verification results showed that both the calculated load position and load position strain matched the measured values with an absolute difference range of 5–60 mm, 0.5–2.5 με, respectively. The application results showed that the strain at the load position calculated by the proposed method had a good correlation with the temperature, as expected. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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17 pages, 3883 KiB

Open AccessArticle

Comparative Study on Complex Modulus and Dynamic Modulus of High-Modulus Asphalt Mixture

by Licheng Guo, Qinsheng Xu, Guodong Zeng, Wenjuan Wu, Min Zhou, Xiangpeng Yan, Xiaomeng Zhang and Jincheng Wei

Coatings 2021, 11(12), 1502; https://doi.org/10.3390/coatings11121502 - 6 Dec 2021

Cited by 11 | Viewed by 3051

Abstract

In the French high-modulus asphalt mixture design system, the complex modulus of the mixture under the conditions of 15 °C and 10 Hz is taken as the design index. However, in China, the dynamic modulus under the conditions of 15 °C, 10 Hz, [...] Read more.

In the French high-modulus asphalt mixture design system, the complex modulus of the mixture under the conditions of 15 °C and 10 Hz is taken as the design index. However, in China, the dynamic modulus under the conditions of 15 °C, 10 Hz, 20 °C, 10 Hz and 45 °C, 10 Hz was taken as the stiffness modulus index of high-modulus asphalt mixture. The difference in modulus values between the two systems caused the pavement structure layer to be thicker and the construction cost to be higher in China. In order to find out the appropriate modulus value of high-modulus asphalt mixture suitable for China’s modulus parameter conditions to better carry out the reasonable design and evaluation of high-modulus asphalt mixture in China, the modulus of four types of high-modulus asphalt mixtures under the two systems through the two-point bending complex modulus test of the CRT-2PT trapezoidal beam and the SPT uniaxial compression dynamic modulus test were analyzed in this paper. Under the premise of meeting the stiffness modulus index of the French high-modulus asphalt mixture, the relationship conversion models between the dynamic modulus and complex modulus of high-modulus asphalt mixture under different temperatures were established. According to the conversion models, the design evaluation value range of dynamic modulus suitable for China’s condition was recommended. It is recommended that the dynamic modulus of China’s high-modulus asphalt mixture at 15 °C and 10 Hz is not less than 16,000 MPa, the dynamic modulus at 20 °C and 10 Hz is not less than 14,000 MPa, and the dynamic modulus at 45 °C and 10 Hz is not less than 2500 MPa. Five kinds of high-modulus asphalt mixtures used in actual road engineering were tested to verify the reliability of the recommended dynamic modulus values based on the modulus conversion model, and the results are consistent with the recommended value range of the model. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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16 pages, 3359 KiB

Open AccessArticle

Mechanism of Polyurethane Binder Curing Reaction and Evaluation of Polyurethane Mixture Properties

by Min Sun, Yufeng Bi, Wei Zhuang, Sai Chen, Pinhui Zhao, Dezheng Pang and Wensheng Zhang

Coatings 2021, 11(12), 1454; https://doi.org/10.3390/coatings11121454 - 26 Nov 2021

Cited by 11 | Viewed by 4130

Abstract

This study focuses on analyzing the curing reaction mechanism of polyurethane (PU) binders and comprehensively evaluating the PU mixture’s properties. The former was investigated by conducting a Fourier transform infrared spectroscopy (FTIR) test on PU binders with different curing times. The volume change [...] Read more.

This study focuses on analyzing the curing reaction mechanism of polyurethane (PU) binders and comprehensively evaluating the PU mixture’s properties. The former was investigated by conducting a Fourier transform infrared spectroscopy (FTIR) test on PU binders with different curing times. The volume change characteristics, construction operation time, and strength formation law were clarified through the splitting tensile test of PU mixtures under different environmental conditions. The optimal PU mixture stacking time and curing time under different environmental conditions were determined. The properties of the PU mixture and asphalt mixture were evaluated and compared through a rutting test, low-temperature bending test, freeze–thaw splitting test, and four-point bending fatigue test. The results show that the physical and chemical curing of the PU binder occurred within the first 24 h of curing, and the reaction speed gradually accelerated to form a polyurea structure 24 h later. It is recommended to stack the PU mixture for 4 h before compaction and to cure it for 2 days before opening under the conditions of 50% humidity and 15–40 °C surrounding temperature. The PU mixture shows better temperature stability and fatigue resistance than the asphalt mixture, and the splitting tensile strength of the PU mixture before and after the freeze–thaw splitting test is also higher. It is clear that the PU mixture is a green road building material with good performance. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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16 pages, 1762 KiB

Open AccessArticle

Study on the Optimum Steel Slag Content of SMA-13 Asphalt Mixes Based on Road Performance

by Wei Chen, Jincheng Wei, Xizhong Xu, Xiaomeng Zhang, Wenyang Han, Xiangpeng Yan, Guiling Hu and Zizhao Lu

Coatings 2021, 11(12), 1436; https://doi.org/10.3390/coatings11121436 - 23 Nov 2021

Cited by 10 | Viewed by 2297

Abstract

To reduce the use of aggregates such as limestone and basalt, this paper used steel slag to replace some of the limestone aggregates in the production of SMA-13 asphalt mixes. The optimum content of steel slag in the SMA-13 asphalt mixes was investigated, [...] Read more.

To reduce the use of aggregates such as limestone and basalt, this paper used steel slag to replace some of the limestone aggregates in the production of SMA-13 asphalt mixes. The optimum content of steel slag in the SMA-13 asphalt mixes was investigated, and the performance of these mixes was evaluated. Five SMA-13 asphalt mixes with varying steel slag content (0%, 25%, 50%, 75%, and 100%) were designed and prepared experimentally. The high-temperature stability, low-temperature crack resistance, water stability, dynamic modulus, shear resistance, and volumetric stability of the mixes were investigated using the wheel tracking, Hamburg wheel tracking, three-point bending, freeze–thaw splitting, dynamic modulus, uniaxial penetration, and asphalt mix expansion tests. The results showed that compared to normal SMA-13 asphalt mixes, the high-temperature stability, water stability, and shear resistance of the SMA-13 asphalt mixes increased and then decreased as the steel slag content increased. All three performance indicators peaked at 75% steel slag content, and the dynamic stability, freeze–thaw splitting ratio, and uniaxial penetration strength increased by 90.48%, 7.39%, and 88.08%, respectively; however, the maximum bending tensile strain, which represents the low-temperature crack resistance of the asphalt mix, decreased by 5.98%. The dynamic modulus of the SMA-13 asphalt mixes increased with increasing steel slag content, but the volume expansion at a 75% steel slag content was 0.446% higher than at a 0% steel slag content. Based on the experimental results, the optimum content of steel slag for SMA-13 asphalt mixes was determined to be 75%. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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15 pages, 3434 KiB

Open AccessArticle

Homogeneity Assessment of Asphalt Concrete Base in Terms of a Three-Dimensional Air-Launched Ground Penetrating Radar

by Xiaomeng Zhang, Wenyang Han, Luchuan Chen, Zhengchao Zhang, Zhichao Xue, Jincheng Wei, Xiangpeng Yan and Guiling Hu

Coatings 2021, 11(11), 1398; https://doi.org/10.3390/coatings11111398 - 17 Nov 2021

Cited by 3 | Viewed by 1812

Abstract

Obtaining the required homogeneity, including uniform thickness and density, is very crucial for controlling the quality of flexible asphalt layers. Although non-destructive testing (NDT) methods are time-saving and less labor-intensive, they only provide indirect measurement data under testing area conditions and strongly depend [...] Read more.

Obtaining the required homogeneity, including uniform thickness and density, is very crucial for controlling the quality of flexible asphalt layers. Although non-destructive testing (NDT) methods are time-saving and less labor-intensive, they only provide indirect measurement data under testing area conditions and strongly depend on the explanations by prediction models. In this study, in terms of the three-dimensional air-launched Ground Penetrating Radar (GPR) technique, the dielectric constant of asphalt concrete base with dry conditions in pavements was detected and calculated by different methods (the Coring Method, Reflection Amplitudes Method and Common Mid-Point Method). According to the calculated dielectric constant, the thickness and density of asphalt concrete base were further calculated and assessed. Comparing with the Coring Method, the Common Mid-Point Method was recommended to calculate dielectric constants in order to obtain reliable thickness of asphalt pavement base. Among the Birefringence, Boettcher, Linearity indicator, and Rayleigh models, the Rayleigh model was suggested to predict the density, and the predicted density exhibited a good correlation coefficient with the measured one. Furthermore, by choosing these proper calculation methods, an assessment was successfully conducted to evaluate homogeneity of a constructed field pavement in practice. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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13 pages, 4764 KiB

Open AccessArticle

Evaluation of Properties and Mechanisms of Waste Plastic/Rubber-Modified Asphalt

by Xiaorui Zhang, Chao Han, Frédéric Otto and Fan Zhang

Coatings 2021, 11(11), 1365; https://doi.org/10.3390/coatings11111365 - 7 Nov 2021

Cited by 8 | Viewed by 2624

Abstract

Waste plastic, such as polyethylene (PE), and waste rubber tires, are pollutants that adversely affect the environment. Thus, the ways these materials are used are important in realizing the goals of reduced CO₂ emissions and carbon neutrality. This paper investigates the fundamental [...] Read more.

Waste plastic, such as polyethylene (PE), and waste rubber tires, are pollutants that adversely affect the environment. Thus, the ways these materials are used are important in realizing the goals of reduced CO₂ emissions and carbon neutrality. This paper investigates the fundamental properties, compatibility, and interaction mechanism of waste plastic/rubber-modified asphalt (WPRMA). Dynamic shear rheology, fluorescence microscopy, a differential scanning calorimeter, and molecular dynamic simulation software were used to evaluate the properties and mechanisms of WPRMA. The results show that the anti-rutting temperature of WPRMA with different waste plastic contents is higher than 60 °C and the optimal dosage of waste PE in WPRMA is 8%, which can enhance the high-temperature properties and compatibility of rubber-modified asphalt. The temperature can directly promote the melting and decomposition of the functional groups in WPRMA and thus must be strictly controlled during the mix production process. The interaction mechanism suggests that waste plastic can form networks and package the rubber particles in rubber-modified asphalt. The main force between waste plastic and rubber is Van der Waals force, which rarely occurs in chemical reactions. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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19 pages, 5287 KiB

Open AccessArticle

Research on the Mechanism of Surfactant Warm Mix Asphalt Additive-Based on Molecular Dynamics Simulation

by Pinhui Zhao, Mingliang Dong, Yansheng Yang, Jingtao Shi, Junjie Wang, Wenxin Wu, Xingchi Zhao, Xu Zhou and Chenlong Wang

Coatings 2021, 11(11), 1303; https://doi.org/10.3390/coatings11111303 - 27 Oct 2021

Cited by 5 | Viewed by 2585

Abstract

Warm mix asphalt (WMA) technology can bring certain environmental and technical benefits through reducing the temperature of production, paving, and compaction of mixture asphalt. Recent studies have shown that some WMA additives are able to reduce the temperature by increasing the lubricating properties [...] Read more.

Warm mix asphalt (WMA) technology can bring certain environmental and technical benefits through reducing the temperature of production, paving, and compaction of mixture asphalt. Recent studies have shown that some WMA additives are able to reduce the temperature by increasing the lubricating properties of asphalt binder-based on the tribological theory, this paper studied the mechanism of adsorbing and lubricating film of base asphalt and WMA on the surface of stone by molecular dynamics (MD) simulation method, and the effect of surfactant WMA additive on the lubrication performance of the shear friction system of “stone–asphalt–stone”. The model of base asphalt lubricating film, including saturates, aromatics, resin and asphaltene, as well as the model of warm mix asphalt lubricating film containing imidazoline-type surfactant WMA (IMDL WMA) additive molecule, were established. The shear friction system of “stone–asphalt–stone” of base asphalt and warm mix asphalt was built on the basis of an asphalt lubrication film model and representative calcite model. The results show that the addition of IMDL WMA additive can effectively improve the lubricity of asphalt, reduce the shear stress of asphalt lubricating film, and increase the stability of asphalt film. The temperature in the WMA lubricating film rises, while the adsorption energy on the stone surface decreases with the increase of shear rate, indicating that the higher the shear rate is, the more unfavorable it is for the WMA lubricating film to wrap on the stone surface. In addition, the shear stress of the WMA lubricating film decreased with increasing temperature, while the shear stress of the base asphalt lubricating film increased first and then decreased, demonstrating that the compactability of the asphalt mixture did not improve linearly with the increase of temperature. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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Review

Jump to: Research

23 pages, 4920 KiB

Open AccessReview

Utilization of Steel Slag in Road Semi-Rigid Base: A Review

by Haibin Li, Canyang Cui, Jun Cai, Mingming Zhang and Yanping Sheng

Coatings 2022, 12(7), 994; https://doi.org/10.3390/coatings12070994 - 15 Jul 2022

Cited by 11 | Viewed by 2607

Abstract

Steel slag (SS) is industrial waste, and there is a large amount of SS to be treated in China. Its disposal generates severe environmental pollution. One of the best ways to use SS is as a road base material. This paper reviews the [...] Read more.

Steel slag (SS) is industrial waste, and there is a large amount of SS to be treated in China. Its disposal generates severe environmental pollution. One of the best ways to use SS is as a road base material. This paper reviews the possibility of using SS in semi-rigid base and evaluates the performance of SS base course. The interaction between three stabilizers (cement, lime–fly ash, and cement–fly ash) and SS is analyzed, and the influence of modifier content on the performance of base course is evaluated. The potential laws between SS, curing time, and unconfined compressive strength, as well as drying shrinkage and temperature shrinkage, are discussed and their effects on the performance of the base course are revealed. The finite element method, discrete element method, and molecular dynamics can be used to analyze the freeze-thaw, rutting resistance, and crack development of SS base. In addition, compared with traditional macadam base, the CO₂ emissions for the use of SS base are slightly more, one of the disadvantages of its use in production, transportation, and compaction. However, considering the overall mechanical, economic, and environmental benefits, it is recommended to use SS in semi-rigid base course. The future research scope of SS as base material is suggested. Full article

(This article belongs to the Special Issue Asphalt Pavement Materials and Surface)

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