Search Results (156)

This study evaluates the mechanical performance and sustainability potential of fiber-reinforced concrete incorporating mine tailings as the fine aggregate and waste tire wire as the reinforcing fiber. The concrete mixtures contained 0.2%, 0.4%, and 0.6% waste tire wire with the natural fine aggregate replaced entirely with Pb-Zn-Cu tailings. The mixtures were tested for porosity, water absorption, compressive strength, splitting tensile strength, flexural strength, toughness, fracture energy, and ductility to assess their mechanical performance and durability. The mine tailings improved the microstructure and reduced water absorption, particularly with tire wire. Using waste tire wire improved the compressive, tensile, and flexural performance; in particular, W-6 showed a 18.2% rise in compressive strength and a more than twofold increase in flexural strength relative to the control mix. The flexural toughness and fracture energy rose by up to 161%, while the ductility peaked at a fiber content of 0.2%. These gains were attributed to fiber crack-bridging and post-cracking energy absorption. The dual-waste system also reduced porosity, improved durability, and demonstrated strong potential for rigid pavement applications such as highways, industrial yards, and airport runways that require high fatigue resistance and a long service life. Beyond technical performance, this approach offers a sustainable solution that lowers maintenance, reduces life-cycle costs, and aligns with circular economy principles. Full article

This in vitro study aimed to evaluate the fatigue behavior of occlusal veneers (OVs) made of lithium disilicate and composition-gradient multilayered zirconia at different thicknesses, incorporating both experimental and theoretical analyses to predict long-term performance. Seventy-two OVs with ceramic layer thicknesses of 0.5 mm, 1.0 mm, and 1.5 mm were fabricated and adhesively bonded to dentin analog composite abutments. All specimens underwent thermomechanical fatigue testing, involving cyclic loading (49 N, 1.6 Hz, 1.2 million cycles) and thermocycling (5–55 °C), simulating five years of clinical function. Fracture patterns were analyzed using light microscopy and scanning electron microscopy. A fatigue lifetime model based on plate-on-foundation theory and slow crack growth was applied to estimate cycles to radial failure. No complete fractures or debonding occurred. However, 50% of 0.5 mm zirconia OVs developed flexural radial cracks from the intaglio surface, while all lithium disilicate and zirconia veneers ≥1.0 mm remained intact. Theoretical predictions closely matched the experimental outcomes, indicating that 0.5 mm zirconia performance aligned with the lower-bound fatigue estimates for 5Y-PSZ. Results suggest that lithium disilicate offers superior fatigue resistance at minimal thickness, while thin zirconia is prone to subsurface cracking. A minimum thickness of 0.7 mm is recommended for zirconia-based OVs. Full article

Objectives: This study aimed to compare the clinical durability, mechanical performance, and stress behavior of three NiTi rotary systems—BlueShaper (Blue), BlueShaper Pro (Dual Wire), and BlueShaper Gold (fully gold-treated NiTi)—through a multimodal evaluation that included simulated instrumentation in 3D-printed replicas, mechanical testing, and finite element analysis (FEA). Methods: Sixty instruments (n = 20 per group) were tested. Simulated canal preparation was conducted in standardized 3D-printed mandibular molars with a 40° mesial root curvature until fracture occurred. Mechanical tests included torsional and flexural loading using a universal testing machine and stainless steel blocks with a standardized 40° curvature. FEA simulations evaluated von Mises stress, shear stress, total deformation, cyclic fatigue behavior, and contact pressure between the instrument and canal wall. Results: BlueShaper Gold prepared an average of 7.5 canals before fracture, followed by BlueShaper Pro (5.67 canals) and Blue (5.00 canals) (p < 0.001). Gold exhibited the highest torsional resistance (6.08 ± 3.08 N) and the longest fatigue life (325 ± 55.7 cycles), with the lowest von Mises stress and damage factor in FEA. BlueShaper Pro showed the longest time to fracture in mechanical testing (73.85 ± 7.10 s) and balanced mechanical behavior. Blue demonstrated the lowest performance across most parameters, including the shortest fatigue life and highest stress concentration. Conclusions: BlueShaper Gold exhibited the highest mechanical strength and fatigue resistance. BlueShaper Pro demonstrated the longest fatigue life and balanced mechanical behavior. Blue showed the lowest performance across most parameters. The strong correlation among clinical, mechanical, and FEA data reinforces the critical role of alloy composition in determining instrument durability, even when design remains constant. Full article

The aim of translucency-enhancing liquids (TEL) is to locally influence the phase composition of zirconia in order to increase its translucency. This study aimed to determine the influence of TEL on 3Y- and 4Y-TZP zirconia concerning roughness, hardness, wear, flexural strength, dynamic stability and fracture force of fixed dental prostheses after thermal cycling and mechanical loading. Two zirconia materials (4Y-TZP; 3Y-TZP-LA, n = 8 per material and test) were investigated with and without prior application of TEL. Two-body wear tests were performed in a pneumatic pin-on-block design (50 N, 120,000 cycles, 1.6 Hz) with steatite balls (r = 1.5 mm) as antagonists. Mean and maximum vertical loss as well as roughness (Ra, Rz) were measured with a 3D laser-scanning microscope (KJ 3D, Keyence, J). Antagonist wear was determined as percent area of the projected antagonist area. Martens hardness (HM; ISO 14577-1) and biaxial flexural strength (BFS; ISO 6872) were investigated. The flexural fatigue limit BFSdyn was determined under cyclic loading in a staircase approach with a piston-on-three-ball-test. Thermal cycling and mechanical loading (TCML: 2 × 3000 × 5 °C/55 °C, 2 min/cycle, H₂O dist., 1.2 × 10⁶ force á 50 N) was performed on four-unit fixed dental prostheses (FDPs) (n = 8 per group) and the fracture force after TCML was determined. Statistics: ANOVA, Bonferroni test, Kaplan–Meier survival, Pearson correlation; α = 0.05. TEL application significantly influences roughness, hardness, biaxial flexural strength, dynamic performance, as well as fracture force after TCML in 3Y-TZP. For 4Y-TZP, a distinct influence of TEL was only identified for BFS. The application of TEL on 3Y- or 4Y-TZP did not affect wear. TEL application has a strong effect on the mechanical properties of 3Y-TZP and minor effects on 4Y-TZP. All effects of the TEL application are of a magnitude that is unlikely to restrict clinical application. 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

Three-dimensional (3D) printing has emerged as a transformative technology in dental splint fabrication, offering significant advancements in customization, production speed, material efficiency, and patient comfort. This comprehensive review synthesizes the current literature on the clinical use, benefits, limitations, and future directions of 3D-printed dental splints across various disciplines, including prosthodontics, orthodontics, oral surgery, and restorative dentistry. Key 3D printing technologies such as stereolithography (SLA), digital light processing (DLP), and material jetting are discussed, along with the properties of contemporary photopolymer resins used in splint fabrication. Evidence indicates that while 3D-printed splints generally meet ISO standards for flexural strength and wear resistance, their mechanical properties are often 15–30% lower than those of heat-cured PMMA in head-to-head tests (flexural strength range 50–100 MPa vs. PMMA 100–130 MPa), and study-to-study variability is high. Some reports even show significantly reduced hardness and fatigue resistance in certain resins, underscoring material-specific heterogeneity. Clinical applications reviewed include occlusal stabilization for bruxism and temporomandibular disorders, surgical wafers for orthognathic procedures, orthodontic retainers, and endodontic guides. While current limitations include material aging, post-processing complexity, and variability in long-term outcomes, ongoing innovations—such as flexible resins, multi-material printing, and AI-driven design—hold promise for broader adoption. The review concludes with evidence-based clinical recommendations and identifies critical research gaps, particularly regarding long-term durability, pediatric applications, and quality control standards. This review supports the growing role of 3D printing as an efficient and versatile tool for delivering high-quality splint therapy in modern dental practice. Full article

This paper reviews the applications and performance advantages of ultra-high-performance concrete (UHPC), engineered cementitious composite (ECC), and recycled aggregate concrete (RAC) in composite flexural members. UHPC is characterized by its ultra-high strength, high toughness, excellent durability, and microcrack self-healing capability, albeit with high costs and complex production processes. ECC demonstrates superior tensile, flexural, and compressive strength and durability, yet it exhibits a lower elastic modulus and greater drying shrinkage strain. RAC, as an eco-friendly concrete, offers cost-effectiveness and environmental benefits, although it poses certain performance challenges. The focus of this review is on how to enhance the load-bearing capacity of composite beams or slabs by modifying the interface roughness, adjusting the thickness of the ECC or UHPC layer, and altering the cross-sectional form. The integration of diverse concrete materials improves the performance of beam and slab elements while managing costs. For instance, increasing the thickness of the UHPC or ECC layer typically enhances the load-bearing capacity of composite beams or plates by approximately 10% to 40%. Increasing the roughness of the interface can significantly improve the interfacial bond strength and further augment the ultimate load-bearing capacity of composite components. Moreover, the optimized design of material mix proportions and cross-sectional shapes can also contribute to enhancing the load-bearing capacity, crack resistance, and ductility of composite components. Nevertheless, challenges persist in engineering applications, such as the scarcity of long-term monitoring data on durability, fatigue performance, and creep effects. Additionally, existing design codes inadequately address the nonlinear behavior of multi-material composite structures, necessitating further refinement of design theories. Full article

Marine risers are essential for offshore resource extraction, yet traditional metal risers encounter limitations in deep-sea applications due to their substantial weight. Fiber-reinforced polymer (FRP) composites offer a promising alternative with advantages including low density and enhanced corrosion/fatigue resistance. However, FRP risers remain susceptible to fatigue damage from vortex-induced vibration (VIV). Therefore, this study investigated VIV behavior of FRP composite risers considering the coupled effect of tensile-flexural moduli, top tensions, slenderness ratios, and flow velocities. Through an orthogonal experimental design, eighteen cases were analyzed using multivariate nonlinear fitting. Results indicated that FRP composite risers exhibited larger vibration amplitudes than metal counterparts, with amplitudes increasing to both riser length and flow velocity. It was also found that the optimized FRP configuration demonstrated enhanced fiber strength utilization. Parameter coupling analysis revealed that the multivariate nonlinear fitting model achieved sufficient accuracy when incorporating two coupled parameters, with the most significant interaction occurring between flexural modulus and top tension. Full article

Using coal gangue in highway base construction provides a sustainable and high-value solid waste recycling approach. This research focused on the mechanical and durability properties of coal gangue from tunneling operations. Six experimental tests, such as unconfined compressive strength (UCS), flexural–tensile strength (FTS), etc., were carried out. The impact of aggregate gradation on coal gangue mixtures’ performance was systematically evaluated. XRD and SEM were used to explore the microstructural mechanisms in cement-stabilized coal gangue–gravel mixtures (CGM). An improved evaluation model, the Delphi–entropy weight–TOPSIS (DET) method, integrating Delphi and entropy weighting, was proposed. Together with an advanced radar chart, it evaluates eight performance criteria, including mechanical, durability, economic, and environmental aspects. The results show that increasing the coal gangue content in mixtures decreases UCS, dynamic compressive rebound modulus (DCRM), FTS, fatigue life, and drying shrinkage performance. Coarse aggregates relieve drying shrinkage, while fine ones improve long-term mechanical properties. Gradation T1~3 promotes the formation of C–S–H gel and AFt crystals, enhancing compactness. Based on the DET model’s quantitative evaluation, T1~3 was determined as the optimal mix for expressway bases, achieving a balance between mechanical performance, durability, and sustainability. Full article

Orthotropic Steel Bridge Decks (OSBDs) are often used in long-span bridges due to their high performance and ease of installation. However, issues such as fatigue cracking and the deterioration of asphalt overlays due to their local stiffness inefficiency necessitate innovative solutions. Orthotropic Steel–Ultra-High-Performance Concrete Composite Bridge Decks (OS-UHPC-CBDs) have enhanced OSBD performance; however, they have disadvantages such as a heavier weight and high initial cost requirements. In this study, an Orthotropic Steel–Lightweight Ultra-High-Performance Concrete Composite Bridge Deck (OS-LUHPC-CBD) is proposed as a solution that integrates a novel Lightweight Ultra-High-Performance Concrete (LUHPC) with a high-strength Q425 steel deck and trapezoidal ribs. A comprehensive experimental investigation, including full-scale four-point bending tests, was undertaken to evaluate the flexural behavior of the proposed OS-LUHPC-CBD compared to the OS-UHPC-CBD. The experimental results show that the proposed OS-LUHPC-CBD has equivalent flexural capacity and improved ductility compared to the OS-UHPC-CBD. This study found the proposed OS-LUHPC-CBD to be a promising solution for application in long-span bridges with an 8.4% lighter weight and a 6.8% lower cost, and with the same ease of construction as OS-UHPC-CBDs. A finite element model with a strong correlation was developed and validated through the experimental results. Based on this, a parametric study was undertaken on the effect of the key geometric design parameters on the flexural capacity of the OS-LUHPC-CBD. Full article

The incorporation of basalt fiber into asphalt mixtures offers potential improvements in their viscoelastic properties. This study explores the addition of basalt fiber to Styrene Butadiene Styrene (SBS)-modified asphalt mixtures with varying SBS contents. Specifically, 0.3% basalt fiber was added to an asphalt mixture containing 3% SBS, and its performance, measured in terms of dynamic stability and flexural strength, was compared with a mixture with 7% SBS content. Additionally, finite element analysis using the Modified Burger’s Logit model was conducted to assess rutting and fatigue behavior. Given the high cost associated with increasing the SBS content, basalt fiber presents a cost-effective alternative without sacrificing performance. Laboratory tests, including the Marshall stability test, dynamic stability, flexural strength, and fatigue tests, were conducted to evaluate both mixtures. Results indicate that the mixture with 0.3% basalt fiber and 3% SBS outperforms the 7% SBS mixture, showing a 47% improvement in dynamic stability and rutting resistance and a 16% increase in flexural strength. Full article

U-shaped flexural plates (UFPs) are promising components for seismic energy dissipation due to their ability to undergo stable plastic deformation under cyclic loading. This study investigates their cyclic behavior through a combination of experimental testing and finite element simulations, focusing on their application in multidirectional damping systems. Key response parameters such as hysteretic behavior, energy dissipation, stiffness degradation, fatigue life, and the effect of loading direction were analyzed. The results demonstrate that UFPs provide reliable hysteretic behavior and maintain mechanical integrity over repeated cycles. The cyclic response was found to be strongly influenced by plate thickness, aspect ratio, and material yield strength. Based on these findings, this work proposes predictive equations for estimating strength, stiffness, fatigue life, and hysteretic damping of UFPs. Additionally, a simplified design procedure is presented for evaluating the strength and stiffness of multidirectional damping systems incorporating UFPs, with potential applications in bridges, buildings, and other structures exposed to complex seismic loading conditions. Full article

Polyurethane grouting technology is widely employed to maintain critical transportation infrastructure, including pavements, airports, and railways. After injection, foamed polyurethane bonds with surrounding aggregates to form a polyurethane–aggregate composite material (PACM). The gradation of aggregates in PACM, stress levels, and loading frequencies significantly influence fatigue performance under cyclic traffic loading. This study investigates the fatigue behavior of three distinct PACM gradation types through three-point bending fatigue tests under varying stress levels and loading frequencies. Results reveal that the finer gradations of PACM tend to exhibit higher flexural stiffness and longer fatigue life but also greater sensitivity to stress levels. Conversely, coarser gradations show lower stiffness but improved energy dissipation characteristics. Additionally, the flexural stiffness modulus, fatigue life, and cumulative dissipated energy decrease with increasing stress levels, while they grow with higher loading frequencies. In contrast, the dissipated angle follows an opposite trend. Additionally, mathematical models were developed to describe the evolution of dissipated energy, uncovering a three-stage pattern dominated by a prolonged plateau phase accounting for over 80% of the fatigue process. Based on this characteristic plateau, fatigue life prediction models were established for each gradation type, achieving high prediction accuracy with relative errors below 10%. These findings not only highlight the significant impact of aggregate gradation on PACM fatigue performance but also provide practical tools for optimizing material design in pavement maintenance. Full article

This review paper investigates the comprehensive impact of various nanomaterials on the mechanical properties and durability of pavement-quality concrete (PQC) with a specific focus on compressive strength, flexural strength, split tensile strength, permeability, abrasion resistance, fatigue performance, and crack relief performance. Despite significant advancements in the use of nanomaterials in concrete, existing research lacks a comprehensive evaluation of their comparative effectiveness, optimal dosages, and long-term durability in PQC. While conventional PQC faces challenges such as low fatigue resistance, high permeability, and susceptibility to abrasion, studies on nanomaterials have largely focused on individual properties rather than a holistic assessment of their impact. Nano SiO₂ and graphene oxide (GO) emerged as the most effective, with optimal dosages of 2% and 0.03%, respectively, leading to substantial improvements in compressive strength (up to 48.88%), flexural strength (up to 60.7%), and split tensile strength (up to 78.6%) through improved particle packing, reduced permeability, and refined microstructure. Nano TiO₂, particularly at a 1% dosage, significantly enhanced multiple properties, including a 36.30% increase in compressive strength, over 100% improvement in abrasion resistance, and a 475% increase in fatigue performance. However, a critical research gap exists in understanding the combined effects of multiple nanomaterials, their interaction mechanisms within cementitious systems, and their real-world performance under prolonged environmental and loading conditions. Most studies have been limited to laboratory-scale investigations, with minimal large-scale validation for pavement applications. The findings indicate that nanomaterials like nano TiO₂, nano CaCO₃, nano Al₂O₃, nano clay, and carbon nanomaterials play crucial roles in improving characteristics like permeability, abrasion resistance, and fatigue performance, with notable gains observed in many cases. This review systematically analyzes the influence of these nanomaterials on PQC, identifies key research gaps, and emphasizes the need for large-scale field validation to enhance their practical applicability. Full article

The smart capsule bubble tile (SCBT) is an innovative flooring solution that combines acupressure-based reflexology with electromagnetic wave stimulation to enhance well-being. Designed for smart buildings and healthcare applications, SCBT integrates traditional construction techniques with advanced healing technologies to create a health-conscious, eco-friendly flooring system. For durability and thermal performance, SCBT tiles are manufactured using conventional concrete methods, enhanced with aluminum oxide (Al₂O₃). Each tile contains multiple pressure point capsules featuring a copper cap that emits electromagnetic waves when exposed to sunlight. This dual-function mechanism stimulates acupressure points on the feet, promoting better blood circulation, reducing stress, and enhancing relaxation. The heat release from the copper caps further improves thermal comfort and energy flow in the body, reinforcing the benefits of reflexology. The performance of SCBT tiles was extensively tested, demonstrating impressive physical and functional properties. They exhibit a flexural strength of 4.6 N/mm², a thermal emissivity of 0.878, a solar reflectance of 0.842, and a water absorption rate of 8.12%. In biomechanical assessments, SCBT showed significant benefits for balance and posture correction. Users experienced a 70.8% reduction in lateral stance ellipse area with eyes open and a 50.5% reduction with eyes closed, indicating improved stability and proprioception. By integrating acupressure and electromagnetic stimulation into flooring design, SCBT promotes a holistic approach to health. This technology supports energy efficiency in smart buildings and contributes to preventive healthcare by enhancing musculoskeletal health and reducing fatigue. SCBT represents a significant step in creating built environments supporting human well-being, merging traditional healing principles with modern material science. Full article