Materials

Research

17 pages, 4183 KiB

Open AccessArticle

Physical, Mechanical, and Durability Performance of Olive Pomace Ash in Eco-Friendly Mortars

by Besma Belaidi, Abderraouf Messai, Cherif Belebchouche, Mourad Boutlikht, Kamel Hebbache, Abdellah Douadi and Laura Moretti

Materials 2025, 18(11), 2667; https://doi.org/10.3390/ma18112667 - 5 Jun 2025

Viewed by 233

Abstract

The cement industry is a major contributor to global CO₂ emissions, driving the research for sustainable alternatives. Olive biomass ash (OBA), a byproduct from burning all types of biomass from the olive tree, has emerged as a potential supplementary cementitious material (SCM). [...] Read more.

The cement industry is a major contributor to global CO₂ emissions, driving the research for sustainable alternatives. Olive biomass ash (OBA), a byproduct from burning all types of biomass from the olive tree, has emerged as a potential supplementary cementitious material (SCM). This study investigates the effects of incorporating olive pomace ash (OPA) as a partial cement substitute (0% to 50% by weight) on mortar properties over extended curing periods. Workability, compressive and flexural strengths, water absorption, and freeze–thaw resistance were evaluated. Up to 20% OPA replacement improved workability while maintaining acceptable strength and durability. Beyond this level, mechanical properties and frost resistance decreased significantly. Correlation analyses revealed strong relationships between flow time and wet bulk density (R² = 0.93), an exponential relationship between 28-day compressive strength and water absorption (R² = 0.87), and linear correlations between pre- and post-freeze–thaw mechanical properties (R² ≥ 0.99 for both compressive and flexural strengths). The results demonstrate that optimal OPA incorporation enhances mortar performance without compromising structural integrity and provides a viable strategy for valorizing agricultural waste. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

18 pages, 5037 KiB

Open AccessArticle

Micromodification Mechanism and High-Temperature Rheological Properties of Activated Rubber/Styrene–Butadiene–Styrene Compound-Modified Asphalt

by Kai Zhang, Xuwen Zhong, Xukun Huang, Weihua Wan, Hai Zhou and Bin Liu

Materials 2025, 18(11), 2643; https://doi.org/10.3390/ma18112643 - 4 Jun 2025

Viewed by 293

Abstract

Currently, research on the modification mechanisms of activated rubber/SBS (styrene–butadiene–styrene) composites and the microscopic processes involved remains limited. To investigate the impact of the rubber activation treatment combined with SBS modifier on asphalt modification, this study employs composite-modified asphalt formulations using either a [...] Read more.

Currently, research on the modification mechanisms of activated rubber/SBS (styrene–butadiene–styrene) composites and the microscopic processes involved remains limited. To investigate the impact of the rubber activation treatment combined with SBS modifier on asphalt modification, this study employs composite-modified asphalt formulations using either a conventional mix or activated rubber in conjunction with SBS. Infrared spectroscopy (IR) and scanning electron microscopy (SEM) were utilized to analyze the chemical components and microscopic morphology of the composite-modified asphalt following activation treatment. Microscopic analysis revealed that the asphalt stirred for 20 min has a characteristic peak with a wave number of 966 cm⁻¹, while the characteristic peak with a wave number of 700 cm⁻¹ is not obvious. That is, the asphalt sample contains the polybutadiene component and a reduced amount of the polystyrene component. Therefore, it can be inferred that the asphalt sample only contains activated rubber, along with less SBS modifier content. Traditional rubber undergoes significant expansion reactions during the mixing stage, but there are difficulties in degradation, which leave large particles and reduce the proportions of the lightweight asphalt components. However, active rubber and SBS mainly expand and degrade more completely during the shear stage, forming many micro-volume particles in asphalt. Additionally, frequency scanning and multiple creep recovery tests were conducted to evaluate the high-temperature rheological properties of the asphalt. The results indicate that activated rubber, doped at 20%, and SBS, doped at 2%, significantly enhance the high-temperature rheological properties of the composite-modified asphalt compared to base asphalt, exhibiting a 417.16% increase in the complex modulus at 64 °C and 1 Hz. Furthermore, these modifiers interact synergistically to improve modification efficiency. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

21 pages, 4462 KiB

Open AccessArticle

Study on the Self-Healing Performance of Polyurethane/Graphene Oxide-Modified Asphalt Based on Dynamic Disulfide Bonds

by Guokai Li, Min Wang, Kezhen Yan and Xiaojin Song

Materials 2025, 18(11), 2549; https://doi.org/10.3390/ma18112549 - 29 May 2025

Viewed by 310

Abstract

In this study, an investigation on using polyurethane/graphene oxide (PU/GO) containing disulfide bonds as a modifier to improve the self-healing ability of asphalt was conducted. PU/GO with different GO contents were synthesized and modified asphalt with different PU/GO dosages (2%, 4%, 6%, 8%) [...] Read more.

In this study, an investigation on using polyurethane/graphene oxide (PU/GO) containing disulfide bonds as a modifier to improve the self-healing ability of asphalt was conducted. PU/GO with different GO contents were synthesized and modified asphalt with different PU/GO dosages (2%, 4%, 6%, 8%) were also prepared. The effect of GO contents on the mechanical and self-healing properties of PU/GO was explored and the impacts of PU/GO contents on the basic properties and self-healing properties of asphalt were also investigated. The results indicated that GO could significantly improve the mechanical properties of PU, as the tensile strength of PU/GO with 1.6% GO increased by more than 100% compared with pure PU. Moreover, GO also had a positive impact on the early-stage self-healing properties of PU/GO. PU/GO could be well dispersed in asphalt and clearly improve the low-temperature performance of base asphalt. When the PU/GO content is 8%, the ductility of modified asphalt was almost 6 times that of base asphalt. The results of both ductility and BBR self-healing tests revealed that the addition of PU/GO improved the self-healing properties of asphalt under room temperature and infrared light conditions. Especially under infrared light conditions, the ductility self-healing coefficient of 8% PU/GO-modified asphalt could reach 100% after healing for 15 min. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

27 pages, 9275 KiB

Open AccessArticle

Characterization of Force Distribution and Force Chain Topology in Asphalt Mixtures Using the Discrete Element Method

by Sudi Wang, Jianxia Wang, Jie Wang, Jian Xu, Yinghao Miao, Qing Ma, Linbing Wang and Tao Liu

Materials 2025, 18(10), 2347; https://doi.org/10.3390/ma18102347 - 18 May 2025

Viewed by 251

Abstract

The force chain network within asphalt mixtures serves as the primary load-bearing structure to resist external forces. The objective of this study is to quantitatively characterize the contact force distribution and force chain topology structure. The discrete element method (DEM) was employed to [...] Read more.

The force chain network within asphalt mixtures serves as the primary load-bearing structure to resist external forces. The objective of this study is to quantitatively characterize the contact force distribution and force chain topology structure. The discrete element method (DEM) was employed to construct simulation models for two stone matrix asphalt (SMA) and two open-graded friction course (OGFC) mixtures. Load distribution characteristics, including average contact force, load bearing contribution and contact force angle, and force chain topological network parameters, clustering coefficient, edge betweenness and average path length, were analyzed to elucidate the load transfer mechanisms. The findings of the present study demonstrate that the average contact force between aggregate–aggregate contact types in specific particle sizes significantly exceeds the average contact force of the same particle size aggregates. For SMA16 and OGFC16 asphalt mixtures, the load-bearing contribution of aggregates initially increases and then decreases with decreasing particle size, peaking at 13.2 mm. SMA13 and OGFC13 mixtures demonstrate a consistent decline in load bearing contribution with decreasing aggregate size. The analysis of the force chain network topology of the asphalt mixture reveals that SMA mixtures exhibited higher average clustering coefficients in force chain topological features in comparison to OGFC mixtures. It indicates that SMA gradations have superior skeletal load-bearing structures. While the maximum nominal aggregate size minimally influences the average path length with a relative change rate of 3%, the gradation type exerts a more substantial impact, exhibiting a relative change rate of 7% to 9%. These findings confirm that SMA mixtures have more stable load-bearing structures than OGFC mixtures. The proposed topological parameters effectively capture structural distinctions in force chain networks, offering insights for optimizing gradation design and enhancing mechanical performance. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

16 pages, 4962 KiB

Open AccessArticle

Seismic Response Mitigation of Reinforced-Concrete High-Speed Railway Bridges with Hierarchical Curved Steel Dampers

by Mingshi Liang, Liqiang Jiang and Jianguang He

Materials 2025, 18(9), 2120; https://doi.org/10.3390/ma18092120 - 5 May 2025

Viewed by 373

Abstract

To address the seismic vulnerability of high-speed railway bridges (HSRBs) in seismically active regions, this study proposes a hierarchical curved steel damper (CSD) designed to mitigate excessive girder displacements induced by conventional isolation devices. The CSD integrates U-shaped and hollow diamond-shaped steel plates [...] Read more.

To address the seismic vulnerability of high-speed railway bridges (HSRBs) in seismically active regions, this study proposes a hierarchical curved steel damper (CSD) designed to mitigate excessive girder displacements induced by conventional isolation devices. The CSD integrates U-shaped and hollow diamond-shaped steel plates to achieve stable energy dissipation through coupled bending deformation. A finite element model is developed, and its hysteretic behavior is confirmed, with an energy dissipation coefficient of 1.82 and an equivalent damping ratio of 12.7%. An integrated high-speed railway track–bridge-CSD spatial coupling model is developed in OpenSees, which incorporates nonlinear springs for interlayer track interactions. Nonlinear time–history analyses under 40 spectrum-matched ground motions reveal that the CSD reduces transverse girder displacements by 73.7–79.2% and attenuates track slab acceleration peaks by 52.4% compared with uncontrolled cases. However, it increases the maximum bending moment at pier bases by up to 18.3%, necessitating supplemental energy-dissipating components for balanced force redistribution. This work provides a theoretical foundation and practical methodology for seismic response control and retrofitting of the HSRB in high-intensity seismic regions. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

18 pages, 8668 KiB

Open AccessArticle

The Preparation and Properties of Ultra-High-Performance Concrete with Aeolian Sand: A Lab Study on the Effect of the Curing Method

by Yang Lv, Boyu Zhao, Jie Zhu, Chenhao He, Yunlu Ge, Yuanshuai Wu, Yanchao Zhu, Jianming Dan, Yang Zhou and Xiangguo Li

Materials 2025, 18(9), 2031; https://doi.org/10.3390/ma18092031 - 29 Apr 2025

Viewed by 263

Abstract

The utilization of aeolian sand (AS) as a substitute for river sand (RS) in ultra-high-performance concrete (UHPC) offers a sustainable solution to address natural sand resource shortages while enhancing AS utilization. This study systematically evaluates the influence of AS content (0–100% RS replacement [...] Read more.

The utilization of aeolian sand (AS) as a substitute for river sand (RS) in ultra-high-performance concrete (UHPC) offers a sustainable solution to address natural sand resource shortages while enhancing AS utilization. This study systematically evaluates the influence of AS content (0–100% RS replacement by mass) on the workability, mechanical properties, and microstructure of UHPC under different curing regimes. All mixtures incorporate 0.65% by volume of straight steel fibers to ensure adequate fiber reinforcement. The results reveal that the spherical morphology, smooth surface nature, and fine particle size of AS enhance the matrix fluidity and reduce the early autogenous shrinkage of UHPC. By employing steam curing at 90 °C for 2 d followed by standard curing for 7 d (M3), UHPC samples with a 60% and 80% AS substitution achieve a compressive strength of 132.4 MPa and 130.8 MPa, respectively; a flexural strength exceeding 18 MPa; a porosity below 10%; and a gel pore content exceeding 60%. The steel fiber reinforcement contributes significantly to the flexural performance, with the fiber–matrix interface quality maintained even at high AS replacement levels. These findings highlight the feasibility of AS as an alternative fine aggregate in UHPC. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Graphical abstract

16 pages, 4717 KiB

Open AccessArticle

Laboratory Investigation of Packing Characteristics and Mechanical Performance of Aggregate Blend

by Weixiao Yu, Yun Li, Zhipeng Liang, Jiaxi Wu, Sudi Wang and Yinghao Miao

Materials 2025, 18(9), 1953; https://doi.org/10.3390/ma18091953 - 25 Apr 2025

Viewed by 232

Abstract

Aggregates are the main material forming the skeleton structure of asphalt mixtures and are of great importance to resist external load for asphalt pavement. This study analyzed the packing characteristics and mechanical performance of aggregate blend to provide a reference for improving the [...] Read more.

Aggregates are the main material forming the skeleton structure of asphalt mixtures and are of great importance to resist external load for asphalt pavement. This study analyzed the packing characteristics and mechanical performance of aggregate blend to provide a reference for improving the bearing capacity of asphalt mixtures. The single-size, two-size, and multi-size aggregate blends were chosen to conduct the laboratory packing and California bearing ratio (CBR) tests. Six particle sizes were selected to design the single-size aggregate blends. Six size combinations were included and various mass ratios were considered for each size combination in the two-size aggregate blends. The multi-size aggregate blends were designed through the gradually filling method according to stone matrix asphalt with a nominal maximum particle size (NMPS) of 16 mm (SMA16) and dense asphalt concrete with an NMPS of 26.5 mm (AC25). The packing characteristics of the blends were quantified by the air voids and the percentage of contribution to the packing volume (PCPV). The mechanical performance of the blends was analyzed by the CBR value. The relationship between packing characteristics and mechanical performance was explored by data fitting. The results showed that the particle size and the size ratio have an effect on the packing characteristics and mechanical performance of aggregate blend. The smaller the particle size, the larger the air void of the blend. The blends composed of larger particles have better load bearing capacity than those composed of smaller particles. The larger the particle size ratio, the greater the air void of the blend and the weaker the load bearing capacity. The particles smaller than 1.18 mm and those smaller than 0.3 mm in AC25 mainly play a role in filling the voids and have little contribution to the load bearing. There is a certain correlation between the packing characteristics and mechanical performance of aggregate blend. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

18 pages, 3404 KiB

Open AccessArticle

Study on Non-Destructive Testing Method of Existing Asphalt Pavement Based on the Principle of Geostatistics

by Duanyi Wang, Chuanxi Luo, Meng Fu, Wenting Zhang and Wenjie Xie

Materials 2025, 18(8), 1848; https://doi.org/10.3390/ma18081848 - 17 Apr 2025

Viewed by 304

Abstract

In the context of the rapid advancement of reconstruction and expansion projects, there has been a significant increase in the demand for the inspection and evaluation of existing asphalt pavements. In order to enhance the efficiency and effectiveness of joint detection using 3D [...] Read more.

In the context of the rapid advancement of reconstruction and expansion projects, there has been a significant increase in the demand for the inspection and evaluation of existing asphalt pavements. In order to enhance the efficiency and effectiveness of joint detection using 3D ground-penetrating radar and falling weight deflectometers, this study investigates non-destructive testing methods for existing asphalt pavements based on geostatistical correlation principles. The relationship between crack rate and deflection is analyzed using group average values. The characteristic sections division method based on the crack rate guideline was realized. Research on the prediction method for deflection using Kriging interpolation has been conducted. Research has revealed that there is a positive correlation between the crack rate and the deflection index. The principle of the singularity index can be employed to divide characteristic sections. The falling weight deflectometer is capable of conducting targeted testing in accordance with characteristic sections. Furthermore, the superior performance of Kriging interpolation in predicting deflection compared with linear interpolation has been demonstrated. According to the Kriging interpolation principle, the detection interval of slow lane deflection should not be more than 100 m. Kriging interpolation on one way lane of matrix data has the best effect, and it can predict deflection using a limited amount of slow lane and hard shoulder data. This facilitates analysis of the changing trend of the deflection index in cases where detection conditions are constrained. This method is of great significance for grasping the true performance status of the existing asphalt pavement structure. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

18 pages, 8797 KiB

Open AccessArticle

Comparison of Microwave Sensitivity and Performance of Asphalt Mastic with Various Steel Slag Powders

by Zeyu Geng, Weixiao Yu, Min Jiang and Yinghao Miao

Materials 2025, 18(6), 1348; https://doi.org/10.3390/ma18061348 - 19 Mar 2025

Viewed by 295

Abstract

Steel slag is a common solid waste, but it has good microwave absorbing ability. The poor microwave sensitivity of asphalt mixture limits the development of microwave maintenance for asphalt pavement. Therefore, it is significant to apply steel slag to asphalt pavement. This study [...] Read more.

Steel slag is a common solid waste, but it has good microwave absorbing ability. The poor microwave sensitivity of asphalt mixture limits the development of microwave maintenance for asphalt pavement. Therefore, it is significant to apply steel slag to asphalt pavement. This study analyzes the difference in the microwave sensitivity and performance between the asphalt mastics with blast furnace slag powder (BFSP), converter slag powder (CSP), refined slag powder (RSP), and limestone powder (LP). First, the chemical composition of BFSP, CSP, RSP, and LP is analyzed by X-ray diffractometer (XRD) and X-ray fluorescence (XRF) tests. Then, the micromorphology characteristics of the asphalt mastic with BFSP, that with CSP, that with RSP, and that with LP are studied using atomic force microscope (AFM) tests. Finally, the rheological properties of the four asphalt mastics are investigated through dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The results show that steel slag powder can effectively improve the microwave sensitivity of asphalt mastic. RSP and CSP can improve the anti-deformation ability of asphalt mastic. In addition, steel slag powders have an adverse effect on the low-temperature cracking resistance of asphalt mastic, but the creep strength and creep rate of asphalt mastic with steel slag powder are within a reasonable range. In general, steel slag powder as filler has great application potential in road engineering. However, it has a certain influence on the performance of asphalt mastic. It is necessary to carry out targeted selection in practical engineering. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

17 pages, 9486 KiB

Open AccessArticle

Study on the Mechanical Properties of Modified Sludge Soil Based on an SM-C Modifier

by Jun Nie, Kai Zhang, Xiangyang Fan, Yixuan Zhang, Guoxu Wei, Xiangyong Yu and Wen Xu

Materials 2025, 18(3), 483; https://doi.org/10.3390/ma18030483 - 21 Jan 2025

Viewed by 636

Abstract

The purpose of this study is to solve the problem of the harmless treatment of dredged silt and soil extraction during road construction in lake areas. The silt in the project area is used as the research material to evaluate its engineering applicability [...] Read more.

The purpose of this study is to solve the problem of the harmless treatment of dredged silt and soil extraction during road construction in lake areas. The silt in the project area is used as the research material to evaluate its engineering applicability as an improved filling material for the roadbed of the lake’s surrounding road. Through indoor pretreatment and a series of mechanical performance tests, including compaction tests, unconfined compressive strength tests (UCS), bearing ratio tests (CBR), triaxial compression tests (CU consolidated undrained), and consolidation tests, we obtained key mechanical parameters of modified sludge soil, such as maximum dry density, optimal moisture content, unconfined compressive strength, bearing ratio, shear strength, and compression characteristics. The research results show that with the increase in modifier dosage, the optimal moisture content of modified sludge soil increases, the maximum dry density decreases, and its compressive strength and shear strength significantly improve. The CBR value also meets the technical requirements of each layer of the roadbed. Specifically, after 7 days of curing, the compaction degree of 10% modified sludge soil can exceed 96%, the unconfined compressive strength reaches 0.819 MPa, the CBR value reaches 17.5, the cohesion measured by triaxial tests is 78 kPa, the internal friction angle is 27°, and it exhibits low compressibility. These findings provide new solutions for environmentally friendly treatment, resource utilization, and road engineering in river and lake sediments. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

26 pages, 8502 KiB

Open AccessArticle

Enhancement of Microwave Heating Technology for Emulsified Asphalt Mixtures Using SiC-Fe₃O₄ Composite Material

by Sheng Xu, Wen Xu, Yixing Chen, Jiaqi Li and Yueguang Li

Materials 2024, 17(18), 4572; https://doi.org/10.3390/ma17184572 - 18 Sep 2024

Cited by 2 | Viewed by 1284

Abstract

The application of microwave heating technology can significantly enhance the water evaporation rate of emulsified asphalt mixtures post paving. To improve the microwave absorption and curing performance of these mixtures, SiC-Fe₃O₄ composite material (SF) was incorporated. This addition aims to [...] Read more.

The application of microwave heating technology can significantly enhance the water evaporation rate of emulsified asphalt mixtures post paving. To improve the microwave absorption and curing performance of these mixtures, SiC-Fe₃O₄ composite material (SF) was incorporated. This addition aims to enhance the microwave absorption efficiency and accelerate the curing process of emulsified asphalt mixtures under microwave heating. This study begins with an analysis of the microwave absorption principles pertinent to emulsified asphalt mixtures. Subsequently, the microwave heating temperature fields of ordinary emulsified asphalt mixture (EAM), SiC emulsified asphalt mixture (S-EAM), Fe₃O₄ emulsified asphalt mixture (F-EAM), and SiC-Fe₃O₄ emulsified asphalt mixture (SF-EAM) were simulated using COMSOL Multiphysics finite element software (COMSOL 6.2). The early strength variations in SF-EAM under different microwave heating durations were then examined through adhesion tests, leading to the proposal of a microwave heat curing process for SF-EAM. Finally, the wear resistance, water damage resistance, rutting resistance, and skid resistance of SF-EAM post-microwave curing were evaluated through wet wheel wear tests, wheel track deformation tests, and road friction coefficient tests. The results indicate that the optimal microwave heating time is 90 s, with the microwave absorption performance of the materials ranked as follows: EAM, S-EAM, F-EAM, and SF-EAM, from lowest to highest. The road performance of SF-EAM complies with specification requirements, and its wear resistance, water damage resistance, and rutting resistance are notably improved after microwave heating. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

33 pages, 12647 KiB

Open AccessArticle

Design and Microwave Absorption Performance Study of SiC-Fe₃O₄ Emulsified Asphalt Mixture

by Xiangyu Jiang, Wen Xu, Yixing Chen and Jiaqi Li

Materials 2024, 17(16), 3935; https://doi.org/10.3390/ma17163935 - 8 Aug 2024

Cited by 1 | Viewed by 1322

Abstract

To address the challenges of slow curing speed and suboptimal microwave absorption during the paving of cold-mixed and cold-laid asphalt mixtures, this study introduces SiC-Fe₃O₄ composite material (SF) into emulsified asphalt mixtures to enhance microwave absorption and accelerate curing via [...] Read more.

To address the challenges of slow curing speed and suboptimal microwave absorption during the paving of cold-mixed and cold-laid asphalt mixtures, this study introduces SiC-Fe₃O₄ composite material (SF) into emulsified asphalt mixtures to enhance microwave absorption and accelerate curing via microwave heating. Initially, based on the maximum density curve theory, an appropriate mineral aggregate gradation was designed, and the optimal ratio of emulsified asphalt mixture was determined through mixing tests, cohesion tests, wet wheel wear tests, and load wheel sand adhesion tests. Subsequently, the influence of SF content on the mixing performance of emulsified asphalt mixtures was analyzed through mixing and consistency tests. Finally, the microwave absorption performance of the mixture was evaluated by designing microwave heating tests under different conditions, using temperature indicators and quality indicators. The experimental results indicate that when SF content ranges from 0% to 4%, the mixing performance of the emulsified asphalt mixture meets specification requirements. The dosage of SF, SF composite ratio, and microwave power significantly impact microwave absorption performance, whereas environmental temperature has a relatively minor effect. The optimal mix ratio for the emulsified asphalt mixture is mineral aggregate:modified emulsified asphalt:water:cement = 100:12.8:6:1. The ideal SF dosage is 4%, with an optimal SiC to Fe₃O₄ composite ratio of 1:1, and a suitable microwave power range of 600–1000 W. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures

Figure 1

14 pages, 4677 KiB

Open AccessArticle

Experimental Investigation of Water Vapor Concentration on Fracture Properties of Asphalt Concrete

by Yu Chen, Tingting Huang, Xuqing Wen, Kai Zhang and Zhengang Li

Materials 2024, 17(13), 3289; https://doi.org/10.3390/ma17133289 - 3 Jul 2024

Viewed by 1317

Abstract

The effect of moisture on the fracture resistance of asphalt concrete is a significant concern in pavement engineering. To investigate the effect of the water vapor concentration on the fracture properties of asphalt concrete, this study first designed a humidity conditioning program at [...] Read more.

The effect of moisture on the fracture resistance of asphalt concrete is a significant concern in pavement engineering. To investigate the effect of the water vapor concentration on the fracture properties of asphalt concrete, this study first designed a humidity conditioning program at the relative humidity (RH) levels of 2%, 50%, 80%, and 100% for the three types of asphalt concrete mixtures (AC-13C, AC-20C, and AC-25C).The finite element model was developed to simulate the water vapor diffusion and determine the duration of the conditioning period. The semi-circular bending (SCB) test was then performed at varying temperatures of 5 °C, 15 °C, and 25 °C to evaluate the fracture energy and tensile strength of the humidity-conditioned specimens. The test results showed that the increasing temperature and the RH levels resulted in a lower peak load but greater displacement of the mixtures. Both the fracture energy and tensile strength tended to diminish with the rising temperature. It was also found that moisture had a significant effect on the tensile strength and fracture energy of asphalt concrete. Specifically, as the RH level increased from 2% to 100% (i.e., the water vapor concentration rose from 0.35 g/m³ to 17.27 g/m³), the tensile strength of the three types of mixtures was reduced by 34.84% on average, which revealed that the water vapor led to the loss of adhesion and cohesion within the mixture. The genetic expression programming (GEP) model was developed to quantify the effect of water vapor concentrations and temperature on the fracture indices. Full article

(This article belongs to the Special Issue Sustainability in Asphalt, Concrete and Pavement Materials: Design, Performance, and Characterization)

► Show Figures