Materials

Research

15 pages, 3213 KiB

Open AccessArticle

An Optimized Approach to Multistage Permanent Deformation Testing of Granular Materials

by Erdrick Pérez-González and Jean-Pascal Bilodeau

Materials 2024, 17(14), 3384; https://doi.org/10.3390/ma17143384 - 9 Jul 2024

Viewed by 743

Accurately characterizing permanent deformation in granular materials subjected to cyclic loading is crucial for pavement design. This paper introduces an alternative approach to characterizing permanent deformation in a framework that reduces the number of load cycle repetitions by applying an alternative analytical strategy [...] Read more.

Accurately characterizing permanent deformation in granular materials subjected to cyclic loading is crucial for pavement design. This paper introduces an alternative approach to characterizing permanent deformation in a framework that reduces the number of load cycle repetitions by applying an alternative analytical strategy based on plastic strain rate variation over time. The methodology uses a cycle-hardening approach to establish correlations between short-term (post-compaction) and long-term (shakedown state) plastic strain accumulation. This alternative approach provides an efficient means to accelerate the characterization of permanent deformation, ensuring the integrity and validity of the assessment in a more time-efficient and resource-optimized way. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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22 pages, 3884 KiB

Open AccessArticle

The Use of Ground Coal Bottom Ash/Slag as a Cement Replacement for Sustainable Concrete Infrastructure

by Sandip Poudel, Samrawit Menda, Joe Useldinger-Hoefs, Lidya E. Guteta, Bruce Dockter and Daba S. Gedafa

Materials 2024, 17(10), 2316; https://doi.org/10.3390/ma17102316 - 14 May 2024

Cited by 2 | Viewed by 1222

Abstract

Cement production requires considerable energy and natural resources, severely impacting the environment due to harmful gas emissions. Coal bottom ash (CBA) and coal boiler slag (CBS), byproducts of coal-fired powerplants having pozzolanic properties, can be mechanically ground and replace cement in concrete, which [...] Read more.

Cement production requires considerable energy and natural resources, severely impacting the environment due to harmful gas emissions. Coal bottom ash (CBA) and coal boiler slag (CBS), byproducts of coal-fired powerplants having pozzolanic properties, can be mechanically ground and replace cement in concrete, which reduces waste in landfills, preserves natural resources, and reduces health hazards. This study was performed to determine the optimum cement replacement amount of ground CBA (GCBA) and ground CBS (GCBS) in concrete, which was 10% for GCBA and 5% for GCBS. GCBA-based concrete exhibited superior tensile strength, modulus of elasticity, and durability compared to the control. In the Rapid Chloride Penetration Test, 10% GCBA concrete resulted in 2026 coulombs at 56 days, compared to 3405 coulombs for the control, indicating more resistance to chloride penetration. Incorporating 2.5% nanoclay in GCBA-based concrete increased the optimum GCBA content by 5%, and the compressive strength of 15% GCBA concrete increased by 4 MPa. The mortar consisting of the finest GCBA(L1) having Blaine fineness of 3072 g/cm² yielded the highest compressive strength (32.7 MPa). The study discovered that the compressive strength of GCBA and GCBS-based mortars increases with fineness, and meeting the recommended fineness limit in ASTM C618 enhances concrete or mortar properties. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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21 pages, 6919 KiB

Open AccessArticle

Study of the Properties and Modification Mechanism of SBS-Modified Asphalt by Dry Process

by Ying Wang, Shaohua Guo, Zhongshi Pei, Shizuo Zhan, Senlin Lin, Kezheng Ma, Junwen Lei and Junyan Yi

Materials 2024, 17(7), 1454; https://doi.org/10.3390/ma17071454 - 22 Mar 2024

Cited by 1 | Viewed by 1264

Abstract

SBS (styrene-butadiene-styrene block copolymer) is a thermoplastic elastomer with properties most similar to rubber. SBS asphalt modifier is mainly composed of a styrene-butadiene-styrene block copolymer with a certain amount of additives and stabilizers. SBS-modified asphalt binder has always been the most commonly used [...] Read more.

SBS (styrene-butadiene-styrene block copolymer) is a thermoplastic elastomer with properties most similar to rubber. SBS asphalt modifier is mainly composed of a styrene-butadiene-styrene block copolymer with a certain amount of additives and stabilizers. SBS-modified asphalt binder has always been the most commonly used pavement material both domestically and internationally. However, conventional wet-process SBS-modified asphalt binder requires manufacturers to produce it in advance and transport it to a mixing plant for blending. This has provided an opportunity for unscrupulous businesses to reduce the amount of SBS by adding other substances, allowing inferior asphalt binder to pass inspections undetected. At the same time, conventional wet-process SBS-modified asphalt tends to undergo phase separation and experience a decline in performance as the storage time increases. However, dry-process SBS-modified asphalt can be directly added at the mixing plant, effectively addressing the issues associated with conventional wet-process SBS-modified asphalt. It also helps to reduce environmental pollution to a certain extent. This study investigates the extraction process of dry-process SBS-modified asphalt binder. It clarifies the performance and modification mechanisms of two types of dry-process SBS-modified asphalt binder at different dosages through various testing methods, including basic indicators, rheological properties, infrared spectroscopy, and fluorescence microscopy. The results indicate that due to the incorporation of oil, crosslinker, solubilizer, and other substances into dry-process SBS modifier, there is a small amount of chemical reaction with asphalt in the melting process. The high- and low-temperature properties and fatigue properties of the two dry-process SBS-modified asphalt binders at a 7% dosage are close to wet SBS-modified asphalt binder at a 5% dosage. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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15 pages, 4463 KiB

Open AccessArticle

Study on the Compatibility of SBR and Asphalt Base Based on Molecular Simulation

by Xiaolei Jiao, Dandan Huang, Song Zhao and Jian Ouyang

Materials 2024, 17(5), 1175; https://doi.org/10.3390/ma17051175 - 2 Mar 2024

Cited by 2 | Viewed by 1004

Abstract

In the field of highway construction, the application of styrene–butadiene rubber (SBR)-modified asphalt has gained popularity across different levels of road surfaces. A crucial aspect in ensuring the efficacy of this modification lies in the compatibility between SBR and the matrix asphalt. To [...] Read more.

In the field of highway construction, the application of styrene–butadiene rubber (SBR)-modified asphalt has gained popularity across different levels of road surfaces. A crucial aspect in ensuring the efficacy of this modification lies in the compatibility between SBR and the matrix asphalt. To address this, the current study utilizes molecular dynamics simulation as a technique. By establishing a model for the SBR-modified asphalt mixture, the research quantifies the compatibility level between the SBR modifier and the asphalt. The aim is to uncover the underlying mechanisms of compatibility between the SBR modifier and the base asphalt, ultimately contributing to the improvement of the storage stability of SBR-modified asphalt, which holds significant importance. The investigation began with the creation of models for both the base asphalt and the SBR modifier. A model for the SBR-modified asphalt blending system was then formulated based on these initial models. After undergoing geometry optimization and annealing procedures, the model attained its lowest energy state, providing a reliable basis for examining the performance of SBR-modified asphalt. The study proceeded to calculate solubility parameters and interaction energies of the system to evaluate the compatibility between the SBR modifier and the base asphalt at various temperatures. The analysis of these parameters shed light on the compatibility mechanism between the two components. Notably, it was found that at a temperature of 160 ℃, the compatibility was significantly enhanced. The findings were further corroborated through scanning electron microscope and rheological tests. The outcomes of this research offer theoretical guidance for the application of SBR-modified asphalt. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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22 pages, 9841 KiB

Open AccessArticle

A Multifunctional Cementitious Composite for Pavement Subgrade

by Mohammad Jawed Roshan, Mohammadmahdi Abedi, António Gomes Correia, Raul Fangueiro and Paulo Mateus Mendes

Materials 2024, 17(3), 621; https://doi.org/10.3390/ma17030621 - 27 Jan 2024

Cited by 4 | Viewed by 1681

Abstract

Premature failure and degradation of layers are the main problems for transportation infrastructure. Addressing these issues necessitates implementing structural health monitoring (SHM) for pavement construction layers. To this end, this research investigated the stress/strain and damage detection capabilities of a self-sensing cementitious composite [...] Read more.

Premature failure and degradation of layers are the main problems for transportation infrastructure. Addressing these issues necessitates implementing structural health monitoring (SHM) for pavement construction layers. To this end, this research investigated the stress/strain and damage detection capabilities of a self-sensing cementitious composite developed for potential utilization in the construction of an intelligent subgrade layer. The prepared self-sensing cementitious composite consisted of 10% cement and hybrid conductive fillers, including multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in sand. Initial findings reveal that the electrical resistivity of the composite is significantly affected by the concentration of MWCNTs/GNPs, with a minimum concentration of more than 0.5% needed to achieve a responsive cementitious composite. Moreover, the piezoresistive analysis indicates that an increase in the concentration of MWCNTs/GNPs and stress levels leads to an improvement in the stress/strain-sensing performance. When the self-sensing cementitious composite is subjected to equivalent stress levels, variations in the fractional changes in resistivity (FCR) exhibit an increasing trend with decreasing resilient modulus, stemming from a decrease in stiffness due to the increased concentration of MWCNTs/GNPs. Additionally, the electrochemical impedance spectroscopy (EIS) analysis demonstrates a contraction for the Nyquist plots under compressive ramp loading prior to failure, followed by the expansion of these curves post-failure. Scanning electron microscopy (SEM) images visually showcase the bridging effects of MWCNTs and the filling effects of GNPs within the composite structure. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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17 pages, 10336 KiB

Open AccessArticle

Investigation of Rutting Performance in Geogrid-Reinforced Asphalt by Penetration Test

by Sheng-Lin Wang, Danrong Wang, Susan Tighe, Sam Bhat and Shunde Yin

Materials 2023, 16(22), 7221; https://doi.org/10.3390/ma16227221 - 18 Nov 2023

Cited by 1 | Viewed by 1000

Abstract

Permanent deformation, or rutting, is one of several critical distresses in flexible pavements. This paper introduced a novel experimental method, a penetration test, for asphalt mixtures to quantify the effects of glass fibre geogrids embedded in asphalt under repeated loading. It was found [...] Read more.

Permanent deformation, or rutting, is one of several critical distresses in flexible pavements. This paper introduced a novel experimental method, a penetration test, for asphalt mixtures to quantify the effects of glass fibre geogrids embedded in asphalt under repeated loading. It was found that the evolution of permanent deformation (ε_p) and its strain rate have three clearly identifiable stages. It was also observed that the presence of the geogrid increased the flow number and the number of cycles to failure significantly compared to control samples. Some of the current ε_p fitting models were found to be valid for deformation prediction under penetration. In addition, a new simple FN calculation method was also proposed based on strain rate and it showed consistent results. In particular, geogrid type “Grid10”, which has smaller aperture size (12.7 mm) had slightly better reinforcement performance regarding the rutting resistance due to its larger contact area. Overall, the test and data analysis method presented in this study could be an important reference for future investigations on geosynthetic-reinforced pavement materials. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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15 pages, 5170 KiB

Open AccessArticle

Performance of Bituminous Binder Modified with Recycled Plastic Pellets

by Haithem Soliman, Paul Osei and Ahmed Shalaby

Materials 2023, 16(20), 6730; https://doi.org/10.3390/ma16206730 - 17 Oct 2023

Cited by 3 | Viewed by 1127

Abstract

Finding beneficial uses for waste plastics has been an environmental challenge for municipalities. A limited number of studies have investigated the performance of asphalt mixtures containing plastic waste in cold regions that experience freeze-thaw cycling. The objective of this study is to evaluate [...] Read more.

Finding beneficial uses for waste plastics has been an environmental challenge for municipalities. A limited number of studies have investigated the performance of asphalt mixtures containing plastic waste in cold regions that experience freeze-thaw cycling. The objective of this study is to evaluate the impact of adding two types of recycled plastic pellets on the high- and low-temperature performance of bituminous binders. Nylon-based (NP) and polyester-based (PP) recycled plastic pellets were used in this study. A PG 58-28 bituminous binder was modified by different dosages of NP and PP plastic pellets. The impact of adding Elvaloy copolymer and polyphosphoric acid on the modified binders was also investigated. Results showed that using recycled plastic pellets as a modifier for bituminous binders improved their elastic response and rutting resistance without affecting their low-temperature performance. The PP modifier showed better elastic behavior and rutting resistance than the NP modifier. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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20 pages, 13365 KiB

Open AccessArticle

Characterizing the Effect of Freeze–Thaw Cycling on Pore Structure of Asphalt Concrete Mixtures Using X-ray CT Scanning

by Mai Alawneh, Haithem Soliman and Ania Anthony

Materials 2023, 16(18), 6254; https://doi.org/10.3390/ma16186254 - 18 Sep 2023

Cited by 8 | Viewed by 1420

Abstract

Freeze–thaw (F–T) cycling presents a challenge when building durable pavement structures in cold regions. Understanding the changes within the microstructure of asphalt concrete (AC) due to F–T conditions is crucial for developing a resilient pavement design. This study investigates the impact of F–T [...] Read more.

Freeze–thaw (F–T) cycling presents a challenge when building durable pavement structures in cold regions. Understanding the changes within the microstructure of asphalt concrete (AC) due to F–T conditions is crucial for developing a resilient pavement design. This study investigates the impact of F–T cycles on five AC mixtures using X-ray computed tomography (CT) scanning. Image analysis was completed to evaluate the changes in the microstructure of the AC samples before and after exposure to 30, 60, and 90 F–T cycles. The changes/degradation in the microstructure were evaluated based on analyzing the distribution and properties of air voids within the AC samples. The results showed that an X-ray CT scan can successfully capture the impact of F–T cycles on the structure of air voids in different AC mixtures. The findings of this research provide guidelines for understanding the mechanism of F–T damage within AC, which can assist in optimizing the performance of AC in cold regions. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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14 pages, 2967 KiB

Open AccessArticle

Analysis of Factors Influencing the Modulus of Hot-Recycled Asphalt Mixture with High RAP

by Zining Chen, Boying Liu, Decheng Feng and Gang Li

Materials 2023, 16(15), 5280; https://doi.org/10.3390/ma16155280 - 27 Jul 2023

Cited by 4 | Viewed by 988

Abstract

Generally, the dynamic modulus and bending stiffness modulus are used to evaluate the mechanical properties of asphalt mixture, and they are also used as basic parameters for asphalt mixture design. Therefore, a study was conducted on changes in the dynamic modulus and bending [...] Read more.

Generally, the dynamic modulus and bending stiffness modulus are used to evaluate the mechanical properties of asphalt mixture, and they are also used as basic parameters for asphalt mixture design. Therefore, a study was conducted on changes in the dynamic modulus and bending stiffness modulus of hot-recycled asphalt mixture with high levels of reclaimed asphalt pavement (RAP) under the influence of different factors: dosage of regenerant, curing temperature, and curing time. The performance of reclaimed asphalt pavement (RAP) was first evaluated. Then, the hot-recycled asphalt mixture was adjusted and designed in order to conduct modulus experiments, composed of the dynamic modulus test and three-point bending test. Finally, the influencing factors were not only qualitatively but also quantitatively analyzed to clarify the change laws of the mechanical parameters of hot-recycled asphalt mixture. The results showed that the modulus of the recycled asphalt mixture first decreased, then increased, and then decreased with increasing dosage of regenerant. As the curing time or temperature increased, the modulus first decreased and then increased. In terms of the dynamic modulus of the hot-recycled asphalt mixture, the curing time had the greatest impact, followed by dosage of the regenerant and curing temperature. For bending stiffness modulus, the influence of dosage of the regenerant was the greatest, followed by curing time and curing temperature. For the bending stiffness modulus of hot-recycled asphalt mixture, the curing conditions had a greater influence compared with the dynamic modulus. Full article

(This article belongs to the Special Issue Design, Application and Performance Improvement of Pavement Materials)

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