Search Results (1,198)

Due to the increasing environmental concerns and the growing generation of electronic waste and plastic, sustainable waste management solutions are essential for the construction industry. This study explores the potential of using electronic waste toner powder (WTP) and recycled low-density polyethylene (LDPE), either individually or in combination as modifiers for asphalt binder to enhance pavement performance and reduce environmental impact. The analysis focused on three key components: (1) binder development and testing; (2) performance evaluation through Marshall stability, indirect tensile strength, and Dynamic Shear Rheometer (DSR) testing for rutting resistance; and (3) sustainability assessment in terms of carbon footprint reduction. The results revealed that the formulation of 25% WTP and 8% LDPE processed at 160 °C achieved the best mechanical performance and lowest carbon index, enhancing Marshall stability by 32% and rutting resistance by 41%. Additionally, this formulation reduced the carbon footprint by 27% compared to conventional asphalt. The study demonstrated that the combination of WTP and LDPE significantly improves the sustainability and performance of asphalt pavements, offering mechanical, environmental, and economic benefits. By providing a quantitative assessment of waste-modified asphalt, this study uniquely demonstrates the combined use of WTP and LDPE in asphalt, offering a novel dual-waste valorization approach that enhances pavement performance while promoting circular economy practices. Full article

To prolong the service life of asphalt pavement and reduce its maintenance cost, a fiber Bragg grating (FBG) sensor encapsulated in carboxylated carbon nanotube (CNT-COOH)-modified gel material suitable for strain monitoring of asphalt pavement was developed. Through tensile and bending tests, the effects of carboxylated carbon nanotubes on the mechanical properties of gel materials under different dosages were evaluated and the optimal dosage of carbon nanotubes was determined. Infrared spectrometer and scanning electron microscopy were used to compare and analyze the infrared spectra and microstructure of carbon nanotubes before and after carboxyl functionalization and modified gel materials. The results show that the incorporation of CNTs-COOH increased the tensile strength, elongation at break, and tensile modulus of the gel material by 36.2%, 47%, and 17.2%, respectively, and increased the flexural strength, flexural modulus, and flexural strain by 89.7%, 7.5%, and 63.8%, respectively. Through infrared spectrum analysis, it was determined that carboxyl (COOH) and hydroxyl (OH) were successfully introduced on the surface of carbon nanotubes. By analyzing the microstructure, it can be seen that the carboxyl functionalization of CNTs improved the agglomeration of carbon nanotubes. The tensile section of the modified gel material is rougher than that of the pure epoxy resin, showing obvious plastic deformation, and the toughness is improved. According to the data from the calibration experiment, the strain and temperature sensitivity coefficients of the packaged sensor are 1.9864 pm/μm and 0.0383 nm/°C, respectively, which are 1.63 times and 3.61 times higher than those of the bare fiber grating. The results of an applicability study show that the internal structure strain of asphalt rutting specimen changed linearly with the external static load, and the fitting sensitivity is 0.0286 με/N. Combined with ANSYS finite element analysis, it is verified that the simulation analysis results are close to the measured data, which verifies the effectiveness and monitoring accuracy of the sensor. The dynamic load test results reflect the internal strain change trend of asphalt mixture under external rutting load, confirming that the encapsulated FBG sensor is suitable for the long-term monitoring of asphalt pavement strain. Full article

Quality requirements for mineral aggregate for concrete used to construct pavement for busy highways are high because of the fatigue traffic loads and environmental exposure. The use of local aggregate for infrastructure projects could result in important sustainability improvements, provided that the concrete’s durability is assured. The objective of this study was to identify the potential alkaline reactivity of local greywacke aggregate and select appropriate mitigation measures against the alkali–silica reaction. Experimental tests on concrete specimens were performed using the miniature concrete prism test at 60 °C. Mixtures of coarse greywacke aggregate up to 12.5 mm with natural fine aggregate of different potential reactivity were evaluated in respect to the expansion, compressive strength, and elastic modulus of the concrete. Two preventive measures were studied—the use of metakaolin and slag-blended cement. A moderate reactivity potential of the greywacke aggregate was found, and the influence of reactive quartz sand on the expansion and instability of the mechanical properties of concrete was evaluated. Both crystalline and amorphous alkali–silica reaction products were detected in the cracks of the greywacke aggregate. Efficient expansion mitigation was obtained for the replacement of 15% of Portland cement by metakaolin or the use of CEM III/A cement with the slag content of 52%, even if greywacke aggregate was blended with moderately reactive quartz sand. It resulted in a relative reduction in expansion by 85–96%. The elastic modulus deterioration was less than 10%, confirming an increased stability of the elastic properties of concrete. Full article

Conventional asphalt is prone to cracking in cold climates due to its poor flexibility and limited ability to regulate temperature. This study investigates the use of low-temperature microencapsulated phase-change materials (MPCMs) to improve both the thermal storage and low-temperature performance of asphalt. MPCMs were incorporated into asphalt through physical blending at various concentrations. The physical, thermal, and rheological properties of the asphalt were then systematically evaluated. Tests included penetration, softening point, ductility, thermogravimetric analysis (TGA), and dynamic shear rheometer (DSR). The addition of MPCMs increased penetration and ductility. It slightly reduced the softening point and viscosity. These changes suggest improved flexibility and workability at low temperatures. Rheological tests showed reductions in rutting and fatigue factors. This indicates better resistance to thermal and mechanical stresses. Bending Beam Rheometer (BBR) results further confirmed that MPCMs lowered creep stiffness and increased the m-value. These findings demonstrate improved crack resistance under cold conditions. Thermal cycling tests also showed that MPCMs delayed the cooling process and reduced temperature fluctuations. This highlights their potential to enhance both energy efficiency and the durability of asphalt pavements in cold regions. Full article

Compared to traditional dense asphalt concrete mixtures, stone mastic asphalt (SMA) generally offers superior performance in terms of its mechanical resistance and extended pavement lifespan. Focusing on the Norwegian scenario, this laboratory-based study investigated the durability of SMA considering the influence of the aggregate shape and petrography. The rock aggregates were classified according to three different-shaped refinement stages involving vertical shaft impact crushing. Further, the aggregates were sourced from three distinct locations (Jelsa, Tau and Dirdal) characterized by different petrographic origins: granodiorite, quartz diorite and granite, respectively. Two mixtures with maximum aggregate sizes of 16 mm (SMA 16) and 11 mm (SMA 11) were designed according to Norwegian standards and investigated in terms of their durability performance. In this regard, two main functional tests were performed for the asphalt mixture, namely resistance against permanent deformation and abrasion by studded tyres, and one for the asphalt mortar, namely water sensitivity. Overall, the best test results were related to the aggregates sourced from Jelsa and Tau, thus highlighting that the geological origin exerts a major impact on SMA’s durability performance. On the other hand, the different aggregate shapes related to the crushing refinement treatments seem to play an effective but secondary role. Full article

An electro-hydraulic servo loading system for a pavement mechanical properties test device was designed. The simulation analysis and test results showed that the PID control met the design requirements, but the output’s maximum error did not. Therefore, a fast terminal sliding mode control strategy with an extended state observer (ESO) was proposed. A tracking differentiator was constructed to obtain smooth differential signals from the input signals. The order of the system was reduced by considering the third and higher orders of the system as the total disturbance, and the states and the total disturbance of the system were estimated using the ESO. The fast terminal sliding mode control achieved fast convergence of the system within a limited time. The simulation results showed that the proposed control strategy improved the system accuracy and anti-disturbance ability, and system control performance was optimized. Full article

The construction of concrete pavements has increased due to their better durability, lifespan, and lower maintenance costs. However, this has resulted in the increased consumption of Portland cement, which is one of the major contributors to carbon emissions. Consequently, the research on alternative binders such as geopolymer concrete has increased in recent times. There are several research studies that investigate the feasibility of geopolymer concrete as a construction material, with limited studies exploring its application in concrete pavements. Therefore, this review study explores the material properties of geopolymer concrete pertinent to the performance of concrete pavements. It also discusses the potential of various industrial and agricultural waste as precursor material in geopolymer concrete. The findings of this paper show that most of the studies used fly ash and ground granulated blast furnace slag (GGBFS) as precursor material in geopolymer pavement-quality concrete, and there is a vast scope in the exploration of other industrial and agricultural waste as precursor material. The mechanical and durability properties of geopolymer pavement-quality concrete are superior to conventional pavement concrete. It is also observed that the drying shrinkage and coefficient of thermal expansion of geopolymer pavement-quality concrete are lower than those of conventional pavement concrete, and this will positively benefit the long-term performance of concrete pavements. The results of fatigue analysis and mechanical load test on the geopolymer pavement-quality concrete indicate its improved performance when compared to the conventional pavement concrete. Full article

Asphalt pavement cracking is an important factor affecting its service life. Under certain conditions, the self-healing behavior of asphalt itself can repair pavement cracks. However, the self-healing ability of asphalt itself is limited. In order to strengthen the self-healing ability of asphalt, the microcapsule wrapped with a repair agent is pre-mixed into the asphalt mixture. When the crack occurs and spreads to the surface of the microcapsule, the microcapsule ruptures and the healing agent flows out to realize the self-healing of the crack. Current microcapsules are mostly prepared with healing agents and bio-oil as core materials, and their high-temperature resistance to rutting is poor. While the epoxy resin contains a three-membered cyclic ether, it can undergo ring-opening polymerization to bond and repair the asphalt matrix. In addition, research on microcapsules mainly focuses on the self-healing properties of microcapsule-modified asphalt. In fact, before adding microcapsules to asphalt to improve its self-healing performance, it is necessary to ensure that the asphalt has a good road performance. On this basis, the self-healing performance of asphalt is improved, thereby extending the service life of asphalt pavement. Therefore, two-component epoxy self-healing microcapsules (E-mic and G-mic) were first prepared in this paper. Then, a temperature scanning test, rheological test of bending beams, and linear amplitude scanning test were, respectively, conducted for the microcapsule/asphalt to evaluate its road performance, including the high-temperature performance, low-temperature crack resistance, and fatigue performance. Finally, the self-healing performance of microcapsules/asphalt was tested. The results showed that the self-developed epoxy self-healing microcapsules were well encapsulated and presented as spherical micron-sized particles. The average particle size of the E-mic was approximately 23.582 μm, while the average particle size of the G-mic was approximately 22.440 μm, exhibiting a good normal distribution. In addition, they can remain intact and unbroken under high-temperature conditions. The results of road performance tests indicated that the microcapsule/asphalt mixture exhibits an excellent high-temperature resistance to permanent deformation, low-temperature crack resistance, and fatigue resistance. The self-healing test demonstrated that the microcapsule/asphalt exhibited an excellent self-healing performance. When the microcapsule content was 4%, the self-healing rate reached its optimal level of 67.8%, which was 149.2% higher than that of the base asphalt. Full article

With the deepening of the green and low-carbon concept in the field of road engineering, the cold construction asphalt pavement technology has developed rapidly due to its advantages such as low energy consumption, low pollution, and convenient construction. The adhesion between emulsified asphalt and aggregates, as a core factor affecting the performance of cold-mixed mixtures and the lifespan of the pavement, has attracted much attention in terms of its mechanism of action and evaluation methods. However, at present, there are still many issues that need to be addressed in terms of the stability control of adhesion between emulsified asphalt and aggregates, the explanation of the microscopic mechanism, and the standardization of testing methods in complex environments. These problems restrict the further promotion and application of the cold construction technology. Based on this, this paper systematically analyzes the current development status, application scenarios, and future trends of the theory and testing methods of the adhesion between emulsified asphalt and aggregates by reviewing a large number of relevant studies. The research aims to provide theoretical support and practical references for the improvement of adhesion in the cold construction asphalt pavement technology. Research shows that in terms of the adhesion mechanism, the existing results have deeply analyzed the infiltration and demulsification adhesion process of emulsified asphalt on the surface of aggregates and clarified the key links of physical and chemical interactions, but the understanding of the microscopic interface behavior and molecular-scale mechanism is still insufficient. In terms of testing methods, although objective and subjective evaluation methods such as mechanical tensile tests, surface energy evaluation, and adhesion fatigue tests have been developed, the standardization of testing, data comparability, and practical engineering applicability still need to be optimized. Comprehensive analysis shows that the research on the adhesion between emulsified asphalt and aggregates is showing a trend from macroscopic to microscopic, from static to dynamic. There are challenges in predicting and controlling the adhesion performance under complex environments, as well as important opportunities for developing advanced characterization techniques and multiscale simulation methods. Full article

In this study, the thermal effectiveness of thermally conductive concrete pavements (TCPs) using silicon carbide (SiC) as a fine aggregate replacement was investigated, compared with that of ordinary Portland cement pavements (OPCPs). The most important purpose of this study is to improve the thermal performance of concrete pavement. Additionally, this study utilized improved thermal properties to enhance the efficiency of pavement heating to prevent icing and snow stacking. Both mixtures met the Korean standards for air content (4.5–6%) and slump (80–150 mm), demonstrating adequate workability. TCP exhibited a higher mechanical performance, with average compressive and flexural strengths of 42.88 MPa and 7.35 MPa, respectively, exceeding the required targets of a 30 MPa compressive strength and a 4.5 MPa flexural strength. The improved strength was mainly attributed to the filler effect and partly due to the van der Waals interactions of the SiC particles. Thermal conductivity tests showed a significant improvement in the TCP (3.20 W/mK), which was approximately twice that of OPCP (1.59 W/mK), indicating an enhanced heat transfer efficiency. In winter field tests, TCP effectively maintained high surface temperatures, overcoming heat loss and outperforming the OPCP. In the site experiment, thermal efficiency was clearly shown in the temperature at the center of the TCP, which was 3.5 °C higher than at the center of the OPCP at the coldest time. These improvements suggest that SiC-reinforced concrete pavements can be practically utilized for effective snow removal and ice mitigation in road systems. Full article

In actual service, asphalt pavement is subjected to freeze–thaw cycles and ultraviolet radiation (UV) over the long term, which can easily lead to mixture aging, enhanced brittleness, and structural damage, thereby reducing pavement durability. This study focuses on the influence of freeze–thaw cycles and ultraviolet aging on the performance of recycled asphalt mixtures. Systematic indoor road performance tests were carried out, and a fatigue prediction model was established to explore the comprehensive effects of recycled asphalt pavement (RAP) content, environmental action (ultraviolet radiation + freeze–thaw cycle), and other factors on the performance of recycled asphalt mixtures. The results show that the high-temperature stability of recycled asphalt mixtures decreases with the increase in environmental action days, while higher RAP content contributes to better high-temperature stability. The higher the proportion of old materials, the more significant the environmental impact on the mixture; both the flexural tensile strain and flexural tensile strength decrease with the increase in environmental action time. When the RAP content increased from 30% to 50%, the bending strain continued to decline. With the extension of environmental action days, the decrease in the immersion Marshall residual stability and the freeze–thaw splitting strength became more pronounced. Although the increase in RAP content can improve the forming stability, the residual stability decreases, and the freeze–thaw splitting strength is lower than that before the freeze–thaw. Based on the fatigue test results, a fatigue life prediction model with RAP content and freeze–thaw cycles as independent variables was constructed using the multiple nonlinear regression method. Verification shows that the established prediction model is basically consistent with the change trend of the test data. The research results provide a theoretical basis and optimization strategy for the performance improvement and engineering application of recycled asphalt materials. Full article

The fatigue resistance of cement-stabilized macadam (CSM) plays a vital role in ensuring the long-term durability of pavement structures. However, limited cementitious material (CM) content often leads to high packing voids, which significantly compromise fatigue performance. Existing studies have rarely explored the coupled mechanism between pore structure and fatigue behavior, especially in the context of solid-waste-based CMs. In this study, a cost-effective alkali-activated sludge gasification slag (ASS) was proposed as a sustainable CM substitute for ordinary Portland cement (OPC) in CSM. A dual evaluation approach combining cross-sectional image analysis and fatigue loading tests was employed to reveal the effect pathway of void structure optimization on fatigue resistance. The results showed that ASS exhibited excellent cementitious reactivity, forming highly polymerized C-A-S-H/C-S-H gels that contributed to a denser microstructure and superior mechanical performance. At a 6% binder dosage, the void ratio of ASS–CSM was reduced to 30%, 3% lower than that of OPC–CSM. The 28-day unconfined compressive strength and compressive resilient modulus reached 5.7 MPa and 1183 MPa, representing improvements of 35.7% and 4.1% compared to those of OPC. Under cyclic loading, the ASS system achieved higher energy absorption and more uniform stress distribution, effectively suppressing fatigue crack initiation and propagation. Moreover, the production cost and carbon emissions of ASS were 249.52 CNY/t and 174.51 kg CO₂e/t—reductions of 10.9% and 76.2% relative to those of OPC, respectively. These findings demonstrate that ASS not only improves fatigue performance through pore structure refinement but also offers significant economic and environmental advantages, providing a theoretical foundation for the large-scale application of solid-waste-based binders in pavement engineering. Full article

Asphalt pavement cracking represents a prevalent form of deterioration that significantly compromises road performance and safety under the combined effects of environmental factors and traffic loading. Crack sealing has emerged as a widely adopted and cost-effective preventive maintenance strategy that restores the pavement’s structural integrity and extends service life. This paper presents a systematic review of the development of crack sealing technology, conducts a comparative analysis of conventional sealing materials (including emulsified asphalt, hot-applied asphalt, polymer-modified asphalt, and rubber-modified asphalt), and examines the existing performance evaluation methodologies. Critical failure mechanisms are thoroughly investigated, including interfacial bond failure resulting from construction defects, material aging and degradation, hydrodynamic scouring effects, and thermal cycling impacts. Additionally, this review examines advanced sensing methodologies for detecting premature sealant failure, encompassing both non-destructive testing techniques and active sensing technologies utilizing intelligent crack sealing materials with embedded monitoring capabilities. Based on current research gaps, this paper identifies future research directions to guide the development of intelligent and sustainable asphalt pavement crack repair technologies. The proposed research framework provides valuable insights for researchers and practitioners seeking to improve the long-term effectiveness of pavement maintenance strategies. Full article

With the increasing demand for highway maintenance, enhancing the resource utilization of reclaimed asphalt pavement (RAP) has become an urgent and widely studied issue. Although foam asphalt cold recycling technology offers significant benefits in terms of resource utilization and energy saving, it still faces challenges, particularly the poor stability of foam asphalt mixtures. This study focuses on optimizing the performance of foam asphalt recycled mixtures through interface modification, aiming to promote the widespread application of foam asphalt cold recycling technology. Specifically, the research follows these steps: First, the optimal mix ratio of the recycled mixtures was determined based on the fundamental properties of foam asphalt and RAP. Then, zinc oxide, silane coupling agents, and amine anti-stripping agents were introduced to modify the recycled mixtures. At last, a series of tests were conducted to comprehensively evaluate improvements in road performance. The results indicate that the silane coupling agent enhances the low-temperature performance and fatigue. The fracture energy reached 526.71 J/m². Zinc oxide improves the low-temperature cracking resistance and dry shrinkage performance. Amine anti-stripping agents have minimal impact on the low-temperature performance. The linear shrinkage was reduced by 2.6%. The results of TOPSIS indicated that silane coupling agent modification exhibits superior fatigue resistance and low-temperature performance, achieving the highest comprehensive score of 0.666. Although amine-based anti-stripping agents improve fatigue life, they are not suitable for modifying foamed asphalt mixtures due to their detrimental effects on low-temperature performance and moisture resistance. Full article

This research evaluates the rheological and mechanical properties of polymer- and nanomaterials-modified bitumen by incorporating nanosilica (NSA), nanoclay (NCY), and Acrylonitrile Styrene Acrylate (ASA) at 5% by weight of the bitumen. The samples were prepared at 165 °C for one hour to obtain homogeneous blends. All samples were subjected to short- and long-term aging to simulate the effects of different operating conditions. The research conducted a series of tests, including consistency, frequency sweep, and multiple creep stress and recovery (MSCR) using the dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The results showed that all modified bitumen outperformed the neat bitumen. The frequency sweep showed a higher complex modulus (G*) and lower phase angle (δ), indicating enhanced viscoelastic properties and, thus, higher resistance to permanent deformation. The BBR test revealed that the bitumen modified with NCY5% has a creep stiffness of 47.13 MPa, a 51.5% improvement compared to the neat bitumen, while the NSA5% has the highest m-value, a 28.5% enhancement compared with the neat bitumen. The MSCR showed that the modified blends have better recovery properties and, therefore, better resistance to permanent deformation under repeated loadings. The aging index demonstrated that the modified bitumen is less vulnerable to aging and maintains their good flexibility and resistance to permanent deformations. Finally, these results showed that adding 5% polymer and nanomaterials improved the bitumen’s’ performance before and after aging by reducing permanent deformation and enhancing crack resistance at low temperatures, thus extending the pavement service life and making them an effective alternative for improving pavement performance in various climatic conditions and under high traffic loads. Full article