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3 pages, 167 KiB

Open AccessEditorial

Special Issue: Road Materials and Sustainable Pavement Design

by Jiaqi Chen, Kezhen Yan and Jun Xie

Appl. Sci. 2024, 14(5), 2054; https://doi.org/10.3390/app14052054 - 29 Feb 2024

Viewed by 2252

Abstract

The study of pavement sustainability encompasses the environmental, economic, and societal impacts of pavements throughout their life cycle [...] Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

Research

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15 pages, 3521 KiB

Open AccessArticle

Microwave Sensitivity Enhanced Asphalt Mastic with Magnetite Powder and Its Performance after Microwave Heating

by Weixiao Yu, Letao Zhang, Yinghao Miao, Zhenlong Gong and Sudi Wang

Appl. Sci. 2023, 13(14), 8276; https://doi.org/10.3390/app13148276 - 17 Jul 2023

Cited by 2 | Viewed by 1139

Abstract

Microwave heating technology is a promising method for asphalt pavement maintenance and de-icing; however, it requires the material to have a good microwave-absorbing ability and can also result in asphalt aging. It is therefore important to develop microwave-sensitive materials used for asphalt pavement [...] Read more.

Microwave heating technology is a promising method for asphalt pavement maintenance and de-icing; however, it requires the material to have a good microwave-absorbing ability and can also result in asphalt aging. It is therefore important to develop microwave-sensitive materials used for asphalt pavement maintenance and study the effects of microwave heating on asphalt aging. This study evaluates the electromagnetic characteristics of limestone powder and magnetite powder and explores the influence of microwave heating on the high-temperature rheological and fatigue properties of microwave sensitivity enhanced asphalt mastic with magnetite powder. A vector network analyzer was used to measure the electromagnetic characteristics of limestone powder and magnetite powder. The magnetite filler asphalt mastics were prepared and subjected to microwave heating for 1 h, 2 h, 3 h, and 4 h. Temperature sweep tests, frequency sweep tests, and linear amplitude sweep (LAS) tests were conducted for magnetite filler asphalt mastics before and after microwave heating. LAS experimental results were analyzed based on viscoelastic continuum damage (VECD) theory. The results show that magnetite powders have better electric field energy storage ability, higher dielectric loss and magnetic loss, and better microwave heating efficiency. The complex shear modulus (G*) and rutting factor (G* × (sin δ)⁻¹) rapidly decrease with the increase in temperature, indicating that the mastics’ ability to resist deformation decreases sharply. The longer the microwave heating time for magnetite filler asphalt mastics, the faster the high-temperature rheological properties decreased as the temperature rose. The fatigue life of magnetite filler asphalt mastics significantly decreases with the increase in strain and microwave heating time. It is suggested to add anti-aging agents into asphalt materials to reduce the aging effect in the process of microwave heating. This study provides a reference for the application of microwave heating technology in asphalt pavement maintenance. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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22 pages, 4719 KiB

Open AccessArticle

Evaluation of Anti-Skid Performance of Asphalt Mixture Based on Accelerated Loading Test

by Houzhi Wang, Yixuan Liu, Jun Yang, Xudong Shi, Xinquan Xu, Sang Luo and Wei Huang

Appl. Sci. 2023, 13(8), 4796; https://doi.org/10.3390/app13084796 - 11 Apr 2023

Cited by 3 | Viewed by 1621

Abstract

Anti-skid performance is the most critical indicator that reflects the safety performance of the road surface. A good anti-skid performance of the road surface guarantees the safe and fast driving of vehicles. However, the asphalt pavement of highways has gradually exposed the anti-skid [...] Read more.

Anti-skid performance is the most critical indicator that reflects the safety performance of the road surface. A good anti-skid performance of the road surface guarantees the safe and fast driving of vehicles. However, the asphalt pavement of highways has gradually exposed the anti-skid performance attenuation, which affects driving safety. Therefore, this study aims to accurately evaluate the anti-skid durability of asphalt mixtures based on a 1/3-size accelerated loading test with different anti-skid surfaces as the research object and explores the key factors affecting the long-term anti-skid performance of asphalt mixtures. The texture depth test and the pendulum value test show that the anti-skid durability of the SMA asphalt mixture is better than that of the AC asphalt mixture. The attenuation prediction equation of the British Pendulum Number (BPN), an anti-skid performance index based on an indoor accelerated loading test, was constructed. After the accelerated loading test stabilized, the BPN and BPN attenuation rate b were used as an index to evaluate the anti-skid durability of the asphalt mixture. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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15 pages, 2255 KiB

Open AccessArticle

Physical and Mechanical Properties of Reclaimed Asphalt Pavement (RAP) Incorporated into Unbound Pavement Layers

by Christina Plati, Maria Tsakoumaki and Konstantinos Gkyrtis

Appl. Sci. 2023, 13(1), 362; https://doi.org/10.3390/app13010362 - 27 Dec 2022

Cited by 5 | Viewed by 2934

Abstract

Against the backdrop of global warming and depletion of natural resources, new techniques and alternative materials need to be explored and integrated into road construction. Reclaimed Asphalt Pavement (RAP) is one of the waste materials that can be reused in new road projects [...] Read more.

Against the backdrop of global warming and depletion of natural resources, new techniques and alternative materials need to be explored and integrated into road construction. Reclaimed Asphalt Pavement (RAP) is one of the waste materials that can be reused in new road projects if its behavior is better understood. Numerous researchers have studied the use of RAP in both bound and unbound pavement layers. However, the mechanical behavior and deformation characteristics of RAP in unbound pavement layers are not fully understood due to its unique properties. For this reason, this paper aims to investigate the performance of RAP in the construction of unbound pavement layers (base and subbase). The methodology used consists of two phases: (i) laboratory tests in terms of physical properties, bearing capacity and permanent deformations generated and (ii) a comparative analysis of the test results. For the laboratory tests, the RAP material was taken from the milling operation of a pavement section to be rehabilitated and blended with virgin aggregates (VA) in different proportions. In addition, a sample consisting of pure VA was used as a reference sample for the comparative analysis of the results. Overall, it is concluded that the use of RAP for admixture in unbound layers is feasible and meets the sustainability requirements of pavement materials and structures without compromising pavement strength. A highlight of the research findings is that RAP with percentages up to 40% is a rational approach for the development of RAP-VA mixes to be incorporated into unbound pavement layers. Nevertheless, the results of the present study support the statement that testing is required each time to define the capabilities of RAP considering local effects and material conditions. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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18 pages, 7133 KiB

Open AccessArticle

Numerical Investigation of Asphalt Concrete Fracture Based on Heterogeneous Structure and Cohesive Zone Model

by Jiaqi Chen, Xu Ouyang and Xiao Sun

Appl. Sci. 2022, 12(21), 11150; https://doi.org/10.3390/app122111150 - 3 Nov 2022

Cited by 9 | Viewed by 2412

Abstract

The fracture behavior of asphalt concrete is closely related to its internal structure. A deep understanding of the relationship between the internal structure and fracture behavior of asphalt concrete is very important for sustainable and durable pavement design. In this paper, a CZM-based [...] Read more.

The fracture behavior of asphalt concrete is closely related to its internal structure. A deep understanding of the relationship between the internal structure and fracture behavior of asphalt concrete is very important for sustainable and durable pavement design. In this paper, a CZM-based FE model was developed to investigate the fracture behavior of asphalt concrete. An image-aided approach was used to generate the 3-D internal heterogeneous structure of asphalt concrete. A series of 2-D cross sections were extracted from the 3-D structure for finite element modeling. Then numerical simulations of SCB tests were conducted and validated with experimental results. With the validated CZM-based FE model, the effects of some critical factors, including temperature, loading rate, aggregate geometry, fracture strength, and fracture energy, on the fracture behavior of asphalt concrete were investigated. The analysis results showed that the average damage of the adhesive elements was higher than that of the cohesive elements at the peak load. At lower temperatures, asphalt concrete tends to crack earlier, and the cracking path tends to be marginally closer to the aggregates. A higher loading rate may induce more, but minor, element damage since the CZM elements in asphalt mortar cannot bear much more stress through deformation. Angular aggregates may induce a higher percentage of damaged elements, especially adhesive-damaged elements. On average, each 10% increase in fracture energy allows the specimen to bear 2.31% more load and 2.82% more displacement. Sufficient fracture energy could improve the ability of asphalt concrete to resist fracture. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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19 pages, 5658 KiB

Open AccessArticle

Research on the Sound Absorption Performance of Porous Asphalt Concrete with Different Air Voids Based on the Finite Element Models

by Jianguang Xie, Yiwei Zhu and Zhanqi Wang

Appl. Sci. 2022, 12(21), 11050; https://doi.org/10.3390/app122111050 - 31 Oct 2022

Cited by 5 | Viewed by 1901

Abstract

This paper aims to investigate the effect of the void structure of porous asphalt concrete (PAC) on the sound absorption performance. The sound absorption coefficient (SAC) spectra of PAC with various voids were measured using the transfer function method and the air void [...] Read more.

This paper aims to investigate the effect of the void structure of porous asphalt concrete (PAC) on the sound absorption performance. The sound absorption coefficient (SAC) spectra of PAC with various voids were measured using the transfer function method and the air void structure was identified from Computed Tomography (CT) scanning images. The finite element model (FEM) of the void structure was established via CT cross-sectional images to research the noise reduction mechanism of PAC. At different frequencies, the sound pressure level distribution and SAC were calculated. The following are the main conclusions: (1) As the void content of PAC increases, the SAC spectrum curve becomes higher, more rightward and wider, while the peak values, their corresponding frequencies and mean values increase. (2) The SAC decreases with the average number of voids within each image and increases with the void equivalent diameter and fractal dimension; there exist linear relationships between these three parameters and the SAC. (3) The sound absorption capacity of the void with larger size and fractal dimension is higher than the smaller one and the voids connected to the upper and lower surfaces provide more noise reduction. (4) The FEMs of PAC can predict the SAC of PAC. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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11 pages, 5050 KiB

Open AccessArticle

The Effect of Ultraviolet Aging Duration on the Rheological Properties of Sasobit/SBS/Nano-TiO₂-Modified Asphalt Binder

by Shengfeng Yang, Kezhen Yan and Wenyao Liu

Appl. Sci. 2022, 12(20), 10600; https://doi.org/10.3390/app122010600 - 20 Oct 2022

Cited by 8 | Viewed by 1616

Abstract

In recent years, nanoparticles have been introduced into warm-mix-modified asphalt to improve asphalt performance after sustaining ultraviolet (UV) aging, yet the evaluation of aging performance is often a descriptive characterization of rheological properties. This study extends rheological characterization with viscoelastic mechanical modeling to [...] Read more.

In recent years, nanoparticles have been introduced into warm-mix-modified asphalt to improve asphalt performance after sustaining ultraviolet (UV) aging, yet the evaluation of aging performance is often a descriptive characterization of rheological properties. This study extends rheological characterization with viscoelastic mechanical modeling to evaluate resistance to UV aging using Sasobit and SBS compound-modified binder blended with nano-titanium dioxide (TiO₂). The extended method comprises characterizations using several rheological properties and a viscoelastic mechanical model, named the 2S2P1D model, on modified asphalt after 3 days, 6 days and 9 days of ultraviolet (UV) aging. The rheological properties of the UV-aged binders were tested at high and medium temperatures in terms of viscosity, complex modulus, phase angle and fatigue factor. Rheological test results showed that nanoparticles generally had no apparent effect on the complex modulus of aged binders regardless of UV aging times. However, the aged binder with nanoparticles showed better fatigue resistance than aged binders without nanoparticles after 3 days of UV aging. As an extension, the black space diagram and 2S2P1D model were used to investigate the viscoelastic properties of these aged binders. The k and h values, as important model parameters, were almost the same and less than one for all UV-aged binders. All investigated aged asphalt binders showed characteristics of a viscoelastic solid in terms of the master curves of the complex modulus and phase angle, and the master curves of the phase angle for all UV-aged binders did not meet the time–temperature equivalence. Moreover, these observations from the 2S2P1D model revealed that aging durations did not affect the viscoelastic mechanical characteristics of warm mix asphalt in this study. The method adopted in this study may promote a comprehensive evaluation of asphalt properties after UV aging, especially considering the viscoelastic mechanical performance. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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16 pages, 3946 KiB

Open AccessArticle

Optimization of Bituminous Road Surfacing Rehabilitations Based on Optimization of Road Asset Value

by Ján Mikolaj, Ľuboš Remek and Matúš Kozel

Appl. Sci. 2022, 12(20), 10466; https://doi.org/10.3390/app122010466 - 17 Oct 2022

Cited by 5 | Viewed by 1653

Abstract

The article presents a complex pavement management system method that utilizes a novel optimization method of rehabilitation plans for individual road sections based on asset value optimization. This method is being implemented and tested by the Slovak Road Administration. The performance-based asset value [...] Read more.

The article presents a complex pavement management system method that utilizes a novel optimization method of rehabilitation plans for individual road sections based on asset value optimization. This method is being implemented and tested by the Slovak Road Administration. The performance-based asset value optimization objectives are Socio-Economic Value and Technical Value of Assets, which breaks down into the Value of Structural Condition and Operational Capacity Value. Life cycle cost analysis is used to find the optimal rehabilitation year of individual road sections to optimize the asset value and minimize financial and economic costs while considering the life cycle extension provided by the rehabilitation in a given year. For the method to be reliable, two main preconditions need to be met. First, the residual bearing capacity calculation method needs to be based on rheological parameters of surfacing materials. This is significant because the residual bearing capacity is used for both choosing the correct rehabilitation technology and calculating the life cycle extension by the rehabilitation action. The second precondition is a reliable pavement performance model. This is significant because pavement deterioration is used to calculate road user costs, which serve as a key input to calculate assets’ Socio-Economic and Operational Capacity value. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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13 pages, 2092 KiB

Open AccessArticle

Unsaturated Hydraulic Conductivity in Composite Porous Media

by Jhan Piero Rojas, Juan Carlos Ruge and Gustavo Adolfo Carrillo

Appl. Sci. 2022, 12(18), 9058; https://doi.org/10.3390/app12189058 - 9 Sep 2022

Cited by 1 | Viewed by 1907

Abstract

Determining the constitutive properties that describe the incipient hydraulic behavior of the materials, including the matrix domains and the distribution of macro and micropores, is crucial to analyzing the preferential water flow in saturated soils, k_s, and unsaturated, k_u. [...] Read more.

Determining the constitutive properties that describe the incipient hydraulic behavior of the materials, including the matrix domains and the distribution of macro and micropores, is crucial to analyzing the preferential water flow in saturated soils, k_s, and unsaturated, k_u. This study focused on determining the hydraulic conductivity in porous media under total and partial saturation conditions. The infiltration characteristics of three reconstituted soils were evaluated using five suction ranges employing conventional permeameters, an automated dual system, and mini-disk infiltrometers. The experimental cycles were carried out in granular soils with mixtures of diatomaceous soils, iron oxide (Fe₂O₃), and calcium carbonate (CaCO₃) in 5–40% proportions. The differences between the granular microstructures of each material and the different hydraulic interaction mechanisms (suctione levels) significantly affected the values of k_s and k_u and the coupling between the pore domains and the defined water regime. Additionally, a lower impact was observed in the data set exposed to higher percentages of Fe₂O₃ and CaCO₃ in different suction ranges, mainly due to a tension effect (meniscus) generated by suction in the granular skeleton. Since both parameters are mutually correlated and have a similar impact between methods and soil cores, k_s and k_u must be optimized simultaneously in each mechanism analyzed. The main findings of this work result in the confirmation that the unsaturated permeability decreases as suction is imposed on the sample. As well as the addition of different materials with Particle Size Distribution finer than the base sample, it also reveals a reduction in hydraulic conductivity, both saturated and unsaturated. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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20 pages, 66297 KiB

Open AccessArticle

Numerical and Experimental Investigation of Recycled Brick Coarse Aggregate Concrete

by Yongcheng Ji, Dayang Wang and Lifeng Wang

Appl. Sci. 2022, 12(18), 9035; https://doi.org/10.3390/app12189035 - 8 Sep 2022

Cited by 7 | Viewed by 1845

Abstract

This paper investigates the mechanical and micro-interfacial properties of recycled concrete. Concrete specimens with recycled brick coarse aggregate (RBCA) admixtures of 0%, 25%, 50%, 75%, and 100% were prepared. Apparent density, slump, and mechanical tests were carried out to evaluate the properties and [...] Read more.

This paper investigates the mechanical and micro-interfacial properties of recycled concrete. Concrete specimens with recycled brick coarse aggregate (RBCA) admixtures of 0%, 25%, 50%, 75%, and 100% were prepared. Apparent density, slump, and mechanical tests were carried out to evaluate the properties and behavior of the recycled concrete. The evolution laws of parameters such as compressive strength, peak strain, and elastic modulus of the recycled concrete specimens were tested and analyzed. Combined with numerical analysis, the stress distribution and damage propagation process of recycled concrete specimens with different RBCA contents were revealed. Furthermore, the RBCA content parameters and the thickness of the interface transition zone were analyzed to predict the mechanical behavior of RBCA concrete. The results show that the slump of fresh recycled concrete is less than 50 mm when the content of RBCA exceeds 50%. The apparent density of concrete is 15.55% lower than that of ordinary concrete when the content of RBCA is 100%. The cube compressive strength of RBCA concrete decreases with increased RBCA content. With increasing RBCA substitution rate, the internal cracks change from discrete to concentrated. The substitution rate of RBCA and thickness of the interfacial transition zone are negatively correlated with compressive strength and positively correlated with elastic modulus and peak stress. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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18 pages, 2785 KiB

Open AccessArticle

Mechanical-Empirical Pavement Design Guide Applied to Portuguese Pavement Structures

by Rita Justo-Silva, Fábio Simões and Adelino Ferreira

Appl. Sci. 2022, 12(11), 5656; https://doi.org/10.3390/app12115656 - 2 Jun 2022

Cited by 2 | Viewed by 2633

Abstract

This paper describes the characteristics of the new pavement design method developed by the American Association of State Highway and Transportation Officials (AASHTO), known as AASHTOWare Pavement-ME^®, and presents the results of its application to the flexible pavement structures presented in [...] Read more.

This paper describes the characteristics of the new pavement design method developed by the American Association of State Highway and Transportation Officials (AASHTO), known as AASHTOWare Pavement-ME^®, and presents the results of its application to the flexible pavement structures presented in the Portuguese Manual of Pavement Structures for the national road network. The results obtained clearly show that it is a very useful tool for road engineers not only for designing new pavement structures but also for the analysis of their performance and for efficiently planning maintenance and rehabilitation interventions. According to the characteristics of the case study that was considered, rutting is the most critical distress, since it presents values close to its threshold value of 20.0 mm, a value that is defined in Portuguese Quality Control Plans. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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20 pages, 12497 KiB

Open AccessArticle

Study on Mechanical Properties of Modified Polyurethane Concrete at Different Temperatures

by Jianhua Lei, Fan Feng, Shu Xu, Weibin Wen and Xuhui He

Appl. Sci. 2022, 12(6), 3184; https://doi.org/10.3390/app12063184 - 21 Mar 2022

Cited by 16 | Viewed by 2975

Abstract

The objective of the present research was to study the effect of temperature on the mechanical properties, failure mode and uniaxial compression constitutive relationship of a modified polyurethane concrete. A total of 24 cube and 27 prism specimens were fabricated, and the uniformity [...] Read more.

The objective of the present research was to study the effect of temperature on the mechanical properties, failure mode and uniaxial compression constitutive relationship of a modified polyurethane concrete. A total of 24 cube and 27 prism specimens were fabricated, and the uniformity of the polyurethane concrete was checked. The compressive test, splitting tensile test and static uniaxial compression test were carried out at 0, 15, 40 and 60 °C. The failure mode, cube compressive strength, splitting tensile strength, axial compressive strength, elastic modulus and the compressive stress–strain curves of the modified polyurethane concrete were obtained. Based on the experimental results, a uniaxial compression constitutive model of the modified polyurethane concrete considering temperature characteristics was proposed. The results show that the elastic modulus, cubic compressive strength, splitting tensile strength and axial compressive strength of the modified polyurethane concrete decrease with the increase of temperature, and the peak strain and ultimate strain increase significantly. When the temperature rises from 0 to 60 °C, the cubic compressive strength, splitting tensile strength and axial compressive strength are decreased by 67.1%, 66.4% and 73.3%, respectively. The calculation results of the proposed constitutive model are in good agreement with the test results. The results are expected to guide the application of the modified polyurethane concrete in bridge deck pavement. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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22 pages, 17745 KiB

Open AccessArticle

Mechanistic–Empirical Analysis of Pavement Performance Considering Dynamic Axle Load Spectra Due to Longitudinal Unevenness

by Jingnan Zhao, Hao Wang, Pan Lu and Jiaqi Chen

Appl. Sci. 2022, 12(5), 2600; https://doi.org/10.3390/app12052600 - 2 Mar 2022

Cited by 4 | Viewed by 3586

Abstract

Pavement distresses are induced by mechanistic responses in pavement structure subjected to dynamic loads of moving vehicles. Pavement surface evenness deteriorates as pavement distresses propagate, which results in dynamic axle loads and faster pavement deterioration. It is vital to consider the dynamic axle [...] Read more.

Pavement distresses are induced by mechanistic responses in pavement structure subjected to dynamic loads of moving vehicles. Pavement surface evenness deteriorates as pavement distresses propagate, which results in dynamic axle loads and faster pavement deterioration. It is vital to consider the dynamic axle load spectra to predict pavement deterioration using traffic-monitoring data. This study aimed to evaluate the effect of dynamic loads and overweight traffic on asphalt pavement overlay performance using mechanistic–empirical (M–E) pavement analysis. The relationship between dynamic load coefficients (DLCs), axle loads, and international roughness index (IRI) was obtained for accurate quantification of dynamic axle loads. Then the dynamic axle load spectra were derived by shifting the static axle load spectra in weigh-in-motion (WIM) data, given the DLC value. AASHTOWare Pavement ME software was used to analyze pavement performance with static and dynamic axle load spectra, and the impact of overweight traffic on asphalt pavement overlay performance. The impact of dynamic loads on reflective fatigue cracking was distinguished at an early stage of the service period and eliminated after the 10-year analysis period, when the propagation of reflective cracking reached a specific level. On the other hand, the consideration of dynamic axle loads increased the impact of overweight truck traffic on pavement distresses, and pavement structures of major highways tend to be more sensitive to overweight traffic because of greater DLC excitement at higher operational speeds. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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24 pages, 4582 KiB

Open AccessArticle

Simulation of Static Tyre–Pavement Interaction Using Two FE Models of Different Complexity

by Tamás Király, Péter Primusz and Csaba Tóth

Appl. Sci. 2022, 12(5), 2388; https://doi.org/10.3390/app12052388 - 25 Feb 2022

Cited by 13 | Viewed by 3220

Abstract

The aim of this research study was to analyse the approaches for establishing a spatial model of a radial truck tyre, based on the finite element method, in order to perform a realistic analysis of static as well as dynamic tyre–pavement interactions. A [...] Read more.

The aim of this research study was to analyse the approaches for establishing a spatial model of a radial truck tyre, based on the finite element method, in order to perform a realistic analysis of static as well as dynamic tyre–pavement interactions. A complex rubber tyre model having a large number of elements was formulated combining current state-of-the-art modelling techniques and, from that model, a simplified model having a smaller number of elements was derived. The complex model proved to be useful only for static loading, because of its high computational demand, while the simplified model proved to be also suitable for dynamic modelling. The two tyre models having different numbers of elements were compared by analysing the contact areas and stresses. Our results indicate that the basic idea of not changing material characteristics while simplifying the model, rebuilding only the carcass using composite shell elements, did not prove to be a satisfactory direction. The results given by the simplified model do not describe the behaviour of the radial tyre well but, rather, describe the behaviour of the diagonal tyre, regarding contact areas and stresses. On the contrary, when analysing stresses and strains in the road pavement structure, the two finite element models provided similar results in practice. Based on our comparison calculations, applying the average contact pressure

q

at analysis points at a 5–8 cm depth, the contact behaviour of the finite element tyre model can be used in any elastic-layer theory-based software. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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21 pages, 6604 KiB

Open AccessArticle

Glass Beads for Road Markings: Surface Damage and Retroreflection Decay Study

by Kevin M. Wenzel, Tomasz E. Burghardt, Anton Pashkevich and Wilhelm A. Buckermann

Appl. Sci. 2022, 12(4), 2258; https://doi.org/10.3390/app12042258 - 21 Feb 2022

Cited by 18 | Viewed by 4935

Abstract

Road markings must be reflectorised with glass beads to be visible to drivers at night, retro-reflecting light from vehicle’s headlights, which is critical for road safety. Four commonly used types of glass beads were evaluated in a laboratory setting for retroreflectivity and their [...] Read more.

Road markings must be reflectorised with glass beads to be visible to drivers at night, retro-reflecting light from vehicle’s headlights, which is critical for road safety. Four commonly used types of glass beads were evaluated in a laboratory setting for retroreflectivity and their surfaces were analysed using optical and scanning electron microscopy. The glass beads were subjected to abrasion and a visual correlation was sought between the measured retroreflectivity and the surface damage. Scratching the glass bead surface with corundum in a rotary drum resulted in major differences in the rates of damage development, depending on the type of the glass beads, and it could be correlated with the rate of retroreflectivity decay. The relative results from abrasion testing were confirmed under tyre action during a turntable evaluation. Based on the outcomes of these tests, service lives, defined as maintaining appropriately high retroreflectivity, were predicted and used to calculate the consumption of raw materials—the basic sustainability parameter. It was shown that the use of ‘premium’ glass beads, enhanced with TiO₂ and made in a proprietary process, provided the road marking system characterised by the lowest long-term consumption of resources. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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15 pages, 5687 KiB

Open AccessArticle

Combined Prediction Method for Thermal Conductivity of Asphalt Concrete Based on Meso-Structure and Renormalization Technology

by Jiaqi Chen, Xingzao Chen, Hancheng Dan and Lanchun Zhang

Appl. Sci. 2022, 12(2), 857; https://doi.org/10.3390/app12020857 - 14 Jan 2022

Cited by 6 | Viewed by 2517

Abstract

Pavement temperature field affects pavement service life and the thermal environment the near road surface; thus, is important for sustainable pavement design. This paper developed a combined prediction method for the thermal conductivity of asphalt concrete based on meso-structure and renormalization technology, which [...] Read more.

Pavement temperature field affects pavement service life and the thermal environment the near road surface; thus, is important for sustainable pavement design. This paper developed a combined prediction method for the thermal conductivity of asphalt concrete based on meso-structure and renormalization technology, which is critical for determining the pavement temperature field. The accuracy of the combined prediction method was verified by laboratory experiments. Using the tested and proven model, the effect of coarse aggregate type, shape, content, spatial orientation, air void of asphalt concrete, and steel fiber on the effective thermal conductivity was analyzed. The analysis results show that the orientation angle and aspect ratio of the aggregate have a combined effect on thermal conductivity. In general, when the aggregate orientation is parallel with the heat conduction direction, the effective thermal conductivity of asphalt concrete in that direction tends to be greater. The effective thermal conductivity of asphalt concrete decreases with the decrease of coarse aggregate content or steel fiber content or with the increase of porosity, and it increases with the increase of the effective thermal conductivity of coarse aggregate. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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14 pages, 2989 KiB

Open AccessArticle

Evaluation of NOx Reduction Effect and Impact on Asphalt Pavement of Surface Treatment Technology including TiO₂ and Asphalt Rejuvenator

by Jong-Won Lee and Cheolmin Baek

Appl. Sci. 2021, 11(23), 11571; https://doi.org/10.3390/app112311571 - 6 Dec 2021

Cited by 7 | Viewed by 2829

Abstract

Nitrogen oxide (NOx), emitted at the highest rate among automobile exhaust gases, is the main cause of air pollution, and various construction technologies are being developed to reduce NOx emissions. In this study, the NOx reduction effect of surface treatment technology for road [...] Read more.

Nitrogen oxide (NOx), emitted at the highest rate among automobile exhaust gases, is the main cause of air pollution, and various construction technologies are being developed to reduce NOx emissions. In this study, the NOx reduction effect of surface treatment technology for road pavements, and the effect of the photocatalytic reaction on asphalt pavements, were evaluated using a photocatalyst. Three types of titanium dioxide (TiO₂) were used as photocatalysts, and an asphalt rejuvenator used to recover aged asphalt was applied as a surface treatment agent. To evaluate the NOx reduction effect, a test device capable of testing large-sized specimens was manufactured and compared with the ISO method, which only allowed the testing of small specimens. In addition, the effect of TiO₂ and the asphalt rejuvenator on the asphalt mixture was analyzed through chemical analysis. The test results of the newly manufactured mixed-tank photo reactor showed the same trend as the ISO test results concerning the evaluation of its NOx removal performance. As a result of the performance evaluation of the surface treatment using TiO₂, the NO removal rate was up to 7.83% when Anatase-type TiO₂ with excellent light efficiency was applied. In addition, when the rejuvenator was used, the oxidation of asphalt, caused by the photoreaction of TiO₂, was reduced. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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21 pages, 5808 KiB

Open AccessArticle

Durability and Safety Performance of Pavements with Added Photocatalysts

by Eva Jimenez-Relinque, Maria Grande, Francisco Rubiano and Marta Castellote

Appl. Sci. 2021, 11(23), 11277; https://doi.org/10.3390/app112311277 - 29 Nov 2021

Cited by 3 | Viewed by 2142

Abstract

The use of photocatalysts to enhance the performance of construction materials with large surfaces exposed to sunlight has become an increasingly common practice in recent decades. Although construction material durability is of crucial importance and is extensively studied when incorporating new additions, very [...] Read more.

The use of photocatalysts to enhance the performance of construction materials with large surfaces exposed to sunlight has become an increasingly common practice in recent decades. Although construction material durability is of crucial importance and is extensively studied when incorporating new additions, very few studies have specifically addressed the effects when adding photocatalysts. This paper discusses the effect of TiO₂-based photocatalysts on pavement durability (porosity, time of transmission of ultrasonic pulses, freeze-thaw resistance and capillary water absorption) and safety (slip resistance and roughness) by comparison of commercial photocatalytic materials of different families and twin materials without the photocatalyst added. The analysis covers concrete tile pavements and porous asphalt treated with photocatalysts in the form of sprayed emulsions, slurry admixtures or built-in during casting. The findings show that changes in the properties of a construction material induced by photocatalytic functionality depend primarily on the porous structure of the matrix and the properties of the resulting photocatalytic surface. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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20 pages, 7839 KiB

Open AccessArticle

Long-Term Monitored Road Degradation Functions as a Tool to Increase Quality of Pavement Design

by Stefan Sedivy, Lenka Mikulova, Peter Danisovic, Juraj Sramek, Lubos Remek and Matus Kozel

Appl. Sci. 2021, 11(21), 9839; https://doi.org/10.3390/app11219839 - 21 Oct 2021

Cited by 5 | Viewed by 2233

Abstract

Ensuring the sustainability of road infrastructure cannot be achieved without the continuous application of new knowledge and approaches within individual management steps. A particularly risky stage in the life cycle of existing roads is the operation phase. High attention is paid to the [...] Read more.

Ensuring the sustainability of road infrastructure cannot be achieved without the continuous application of new knowledge and approaches within individual management steps. A particularly risky stage in the life cycle of existing roads is the operation phase. High attention is paid to the environmental, financial and social impacts and benefits of individual processes applied by road managers. These processes meet in pavement management systems (PMS), which, however, cannot work reliably without the necessary input data. Information on the development of the technical condition of the road can also be included among the most important data. The paper brings the first outputs from several years of research of measurements on the Slovak 1st class road. Its aim is to gradually determine the degradation functions for the needs of Slovak geographical, climatic and transport conditions. The secondary objective is to verify the reliability of non-destructive measurement procedures of the technical condition of the road. Emphasis is placed on the application of such mathematical procedures that can not only reliably bring about the determination of past developments in the roadway, but can also present the expected picture of future developments. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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16 pages, 11440 KiB

Open AccessArticle

Strains Comparisons of Unbound Base/Subbase Layer Using Three Elasto-Plastic Models under Repeated Loads

by Ning Li, Biao Ma and Hao Wang

Appl. Sci. 2021, 11(19), 9251; https://doi.org/10.3390/app11199251 - 5 Oct 2021

Cited by 1 | Viewed by 2044

Abstract

The constitutive model is the crucial part for the finite element analyses. To study the elasto-plastic properties of unbound granular materials (UGMs) under repeated vehicular loads, an elasto-plastic constitutive model called revised spatially mobilized plane (SMP) was proposed and validated. In this study, [...] Read more.

The constitutive model is the crucial part for the finite element analyses. To study the elasto-plastic properties of unbound granular materials (UGMs) under repeated vehicular loads, an elasto-plastic constitutive model called revised spatially mobilized plane (SMP) was proposed and validated. In this study, the revised SMP model was used for the plastic strain analyses of a typical three-layer pavement structure. To make comparisons, the Mohr-Coulomb and Druck-Prager models were employed for the numerical computation. The results show that plastic tensile and compressive strains in the horizontal and vertical directions appear on the top surface of UGM using the revised SMP model, but no plastic strains are produced by the Mohr-Coulomb and Druck-Prager models. The distribution of plastic strains in the revised SMP model had a good relationship with the actual loading areas under the vehicular loading, which related to the rutting. With the Mohr-Coulomb and Druck-Prage models, a great plastic strain was produced during the first several loading cycles and hardly increased in the following loading cycles, while the plastic strain in the revised SMP model presented an obvious increasing tendency with increased loading cycles. The predicted permanent deformations of the revised SMP, Mohr-Coulomb and Druck-Prage models were 0.557 mm, 0.78 mm and 0.155 mm, respectively. Our work reveals that the Mohr-Coulomb model may over-predict and Druck-Prage model may under-predict the rutting of pavement in early loading stage and the results proved that the revised SMP model had advantages in the description of the plastic strain of UMG under repeated loads. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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Review

Jump to: Editorial, Research

39 pages, 7995 KiB

Open AccessReview

Review of Visualization Technique and Its Application of Road Aggregates Based on Morphological Features

by Lei Wang, Yongsheng Yao, Jue Li, Yiyang Tao and Kefei Liu

Appl. Sci. 2022, 12(20), 10571; https://doi.org/10.3390/app122010571 - 19 Oct 2022

Cited by 12 | Viewed by 2749

Abstract

The sustainable performance of asphalt pavement depends on the quality and mix design of road aggregates. Identifying aggregate morphology and size is a prerequisite step for material design and numerical modeling of asphalt mixtures. The paper aims to review the morphometric measurement, characteristic [...] Read more.

The sustainable performance of asphalt pavement depends on the quality and mix design of road aggregates. Identifying aggregate morphology and size is a prerequisite step for material design and numerical modeling of asphalt mixtures. The paper aims to review the morphometric measurement, characteristic parameters and visualization technique of road aggregates. Types, calculation methods and advantages of aggregate morphological characteristics are highlighted. The applications of aggregate morphological features on the volumetric design, compaction processes, mechanical properties and size effect of asphalt mixtures are summarized. Although digital image processing technology has been studied for years, aggregates in the complex accumulation are still difficult to measure accurately. In the current research, the morphological parameters of aggregates remain diverse without a standard protocol. Compared to theoretical models, numerical models have more difficulties establishing irregular morphology features in the simulated specimens but provide a volume parameter closer to the real value. The future investigation of road performance under dynamic loading should account for the microscopic evolution of shape, orientation and distribution of aggregates over time. Full article

(This article belongs to the Special Issue Road Materials and Sustainable Pavement Design)

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