Search Results (739)

Asphalt pavements are frequently subjected to fatigue cracking, rutting, and surface wear, which accelerate maintenance needs and shorten service life. This study evaluates the performance enhancement of NHA Class B dense-graded asphalt mixtures (12.5 mm NMAS) prepared with a 60/70 penetration grade binder through carbon fiber (CF) reinforcement. Chopped fibers (~12.7 mm) were incorporated via the dry mixing process at dosages of 0.5%, 1.0%, and 1.5% by binder weight. The results indicate that the 1.0% CF mixture delivered optimal performance, with ITS increasing by 51.9%, Marshall stability improving by 38.4%, resilient modulus rising by 42.6%, and rut depth decreasing by 69.2% compared to the unmodified control. Dynamic stability reached 33,750 passes/mm, demonstrating substantial resistance to permanent deformation. Statistical analysis using one-way ANOVA confirmed that all improvements were significant (p < 0.05). Despite a ~6.7% increase in initial cost, the CF-modified mix exhibited strong economic viability, achieving a benefit–cost ratio of 4.79 and significant life-cycle savings over 20 years. These findings underscore carbon fiber as an effective modifier for developing durable, high-performance asphalt composites with reduced maintenance requirements. This work contributes to the advancement of smart and sustainable pavement technologies for resilient transportation infrastructure. Full article

This paper proposes an innovative contact sponge–fluorescent tracer technique for the rapid, non-destructive detection of 1–100 μm microcracks in cementitious materials. The technique combines a porous sponge carrier with a moisture-sensitive fluorescent tracer: after the sponge adsorbs the aqueous dye solution, capillary action drives fluorescent molecules into microcracks upon contact with the wall, ensuring stable luminescence during a 30-day continuous observation period. This technique was applied to cement paste specimens with three different water-to-cement ratios, dried at 105 °C for varying durations to induce drying–shrinkage microcracks. Results demonstrate that the technique clearly characterizes microcrack networks with high resolution and excellent stability. Under the same drying duration, the average microcrack width decreases with an increasing water-to-cement ratio, while the total crack length and fractal dimension increase. Regression analysis reveals that the average crack width is the primary factor controlling capillary water absorption. This method enables the early detection of microcracks in critical infrastructure such as tunnels and bridges, facilitating timely maintenance and reducing deterioration risk. Full article

This study investigates the effect of microstructure on water-induced embrittlement of dual-phase austempered ductile iron (ADI). Dual-phase ADI materials were produced by austenitization at 780, 800, 820, and 840 °C followed by austempering at 400 °C/1 h, resulting in microstructures composed of varying fractions of free ferrite and ausferrite. Tensile properties were evaluated under dry conditions and in distilled water. The embrittlement zones were observed in all samples investigated; however, they were not critical in all cases. The results indicate that free ferrite is less sensitive to water-induced embrittlement, whereas increasing ausferrite content promotes the formation and growth of the embrittlement zone. Elongation was identified as the most sensitive mechanical parameter, showing statistically significant reductions of up to ~80% for microstructures containing more than ~65% ausferrite, while proof strength remained largely unaffected. Fracture surface analysis revealed fatigue-like striation features within the embrittlement zone, indicating cyclic crack initiation and propagation. Based on correlations between tensile behavior, fracture morphology, and microstructural features, a water-induced embrittlement mechanism involving cyclic local chemisorption and surface-initiated crack growth is proposed. These findings highlight the critical roles of phase type, volume fraction, and spatial distribution in controlling the resistance of dual-phase ADI to embrittlement in aqueous environments. Full article

Archaeological bone artifacts frequently exhibit diminished mechanical integrity as a result of organic matrix degradation. Under adverse environmental conditions, such artifacts are particularly susceptible to surface cracking and disintegration into powder. It is urgently necessary to develop protective materials that possess high permeability, strong reinforcing power and good compatibility. This study evaluated the protective performance of a novel Acrylate Metal Complex (AMC) and two conventional commercial consolidants (acrylic resin Paraloid B72 and ethyl silicate-based material Remmers 300) on fragile bone artifacts. Using simulated samples resembling bone artefacts, a systematic evaluation was conducted to assess the penetration, mechanical reinforcement efficacy, microstructural modifications, chromatic impact, and aging resistance of three consolidants. The results indicate that AMC demonstrates optimal permeation capability and can significantly enhance the surface hardness of bone specimens, achieving an increase of 7.7%. The colorimetric changes observed in all three reinforced materials following treatment remained within acceptable limits (ΔE* < 1.5). Accelerated aging tests—including 300 h of UV irradiation and 30 cycles of alternating dry-wet conditions—demonstrated that bone-mimetic composites reinforced with AMC exhibited significantly superior aging resistance relative to those treated with B72 and Remmers 300. In the actual application verification of the archaeological bone relics, the surface hardness of the reinforced AMC increased by 10%, the wave velocity increased by 14.8%, and there was no glare or crust on the surface. Comprehensive comparison shows that AMC outperforms traditional commercial materials in key performance indicators, demonstrating great potential as a next-generation bone relic conservation material. Full article

Ultrasonic testing is a prevalent method for non-destructive evaluation of railway rails; however, conventional Time-of-Flight (ToF) approaches applied in practical dry-coupled inspections often rely on simplified assumptions regarding wave propagation velocity and neglect complex waveform characteristics. This paper presents a robust depth estimation framework for surface-breaking cracks that enhances sizing accuracy through effective velocity calibration and Hilbert envelope extraction. Unlike standard methods that assume the free-space speed of sound in air (343 m/s) for wave propagation within the air-filled gap of a surface-breaking crack, we propose an effective velocity model derived from in situ calibration to account for the boundary layer viscosity and thermal conduction effects within narrow crack geometries. The signal processing chain incorporates spectral analysis, band-pass filtering, and Hilbert Transform-based envelope detection to mitigate noise and resolve phase ambiguities. Experimental validation on steel specimens with controlled defects (0.2–10.0 mm) demonstrates that the proposed method achieves an exceptional linear correlation (R² ≈ 0.9976). The calibrated effective velocity was determined to be 289.3 m/s, approximately 15.6% lower than the speed of sound in air, confirming the significant influence of confinement effects. Furthermore, excitation parameters were optimized, identifying that high-voltage excitation (≥110 V) and a tuned pulse width (≈150 ns) are critical for maximizing the signal-to-noise ratio. The results confirm that combining physical model calibration with advanced signal analysis significantly reduces systematic errors, paving the way for portable, high-precision rail inspection systems. Full article

This study investigates the durability performance of bamboo fiber recycled aggregate concrete (BFRAC) in a sulfate attack environment by simulating harsh conditions through dry–wet cyclic tests. It compares the sulfate attack resistance of steel fiber recycled aggregate concrete (SFRAC) and BFRAC, analyzing their durability performance. The experiments were designed with bamboo fiber admixtures (by volume) of 1%, 1.5%, and 2%, using a 5% Na₂SO₄ solution for dry–wet cycling. The tests evaluated the mass loss rate, microstructure evolution, compressive strength corrosion resistance coefficient, split tensile strength, and dynamic modulus at cycles 0, 30, 60, 90, and 120. A damage model was established to predict the concrete’s damage life. The results showed that as the number of wet and dry cycles increased, the specimens developed cracks, mortar detachment, and fiber rusting on the surface. The mass loss initially increased and then decreased, while the relative dynamic modulus of elasticity and compressive strength exhibited a trend of increasing followed by a decrease. Bamboo fiber concrete demonstrated better durability in terms of compressive strength and splitting tensile strength. Among the BFRAC specimens, those with a 1.5% bamboo fiber admixture had the longest predicted service life, as determined by the Weibull distribution model. Full article

Expansive or soft soils cause significant geotechnical issues for foundations and subgrades because they show swell–shrink behaviour under wet and dry conditions. These volume changes can result in cracking, heaving, uneven settlement, and structural or pavement damage, ultimately increasing maintenance and repair costs. While traditional Portland cement and lime stabilisers effectively enhance soil strength and reduce swell–shrink behaviour, the cement production process is responsible for only approximately 7%–8% of global CO₂ emissions, prompting a transition toward sustainable alternatives. This comprehensive review consolidates recent advancements in soil stabilisation using industrial by-products, such as fly ash, ground granulated blast furnace slag (GGBS), steel slag, cement kiln dust, silica fume, bottom ash, red mud, waste foundry sand, brick dust, calcium carbide residue, water treatment sludge, etc. These materials leverage pozzolanic and latent hydraulic properties to form C-A-H, C-S-H, and N-A-S-H gels, thereby densifying the soil microstructure, improving CBR (%), UCS, and reducing plasticity and swelling potential. Optimisation studies indicate that industrial waste stabilisers often match or exceed conventional binder performance, GGBS-steel slag combinations yielding 105% higher UCS than ordinary Portland cement, and silica fume enhances cement-stabilised soils by 22% at reduced dosages. However, inherent compositional variability, long-term durability concerns including sulfate attack and freeze–thaw degradation, and the absence of standardised design guidelines restrict large-scale implementation. This review integrates mechanistic, microstructural, and sustainability insights, highlighting the need for durability research, standardised methods, and large-scale field validation to advance industrial waste-based stabilisation within circular construction practices in geotechnical engineering. Full article

A low-temperature tempering staged drying process was proposed in this study to minimize quality degradation and improve drying efficiency during waxy corn drying. Experiments of continuous drying, low-temperature tempering drying, and low-temperature tempering staged drying were conducted to investigate the drying characteristics and quality of waxy corn. The results showed that the low-temperature tempering drying process could shorten the effective drying time and increase the drying rate during the latter stage of the drying process. Under the same hot air temperature, increasing the tempering temperature from 30 °C to 40 °C reduced the effective drying time by 20 min. The Modified Henderson and Pabis model exhibited the best fit to the experimental drying data (R² ≥ 0.9864). The microstructural images of the waxy corn flour showed no significant changes among the experimental groups. The color difference (ΔE) of the continuous drying group was higher than that of the other experimental groups. Both the low-temperature tempering drying process and the low-temperature tempering staged drying process caused less damage to the waxy corn with a relatively lower crack ratio, thereby leading to a reduced electrical conductivity value. The starch content of the 80 °C–60 °C–40 °C group was higher than that of the other experimental groups. Based on comprehensive evaluation of the drying characteristics, the color parameters, and the quality of the dried waxy corn, the 80 °C–60 °C–40 °C group represents a favorable alternative. Full article

Fiber-reinforced polymer (FRP)-reinforced concrete beams are increasingly used in infrastructure, yet their flexural behavior under fatigue and harsh environmental conditions remains insufficiently studied. This study investigates the fatigue response and structural behavior of 12 glass-FRP (GFRP)-reinforced concrete beams under four environmental regimes: indoor control, continuous alkaline immersion, cyclic wet–dry alkaline immersion, and outdoor exposure in Montreal. Four pre-cracked beams were subjected to up to one million load cycles, while deflection and crack mouth opening displacement (CMOD) were monitored. Structural behavior was evaluated in terms of flexural capacity, load–deflection response, crack development (CMOD), stiffness degradation, and serviceability limit state (SLS) performance before and after fatigue loading. Results show that W&D and Immersion beams exhibited the largest deflections (δ_exp/δc_ode = 158% and 92%, respectively), whereas Outdoor and Control beams maintained robust load capacity with minimal fatigue effect. Flexural toughness indices varied from 8.61 to 18.45 across specimens, highlighting environmental influence on energy absorption. Serviceability limit state criteria were reached between 400,000 and 850,000 cycles, depending on conditioning. Overall, GFRP-RC beams demonstrated strong residual strength and predictable degradation patterns, providing quantitative insight into fatigue performance under combined environmental and cyclic loading. Full article

Synthetic microfibres released during textile drying are considered an emerging source of microplastic pollution, yet this waste stream is generally discarded without treatment. This study investigates a valorisation route by incorporating waste dryer-filter microfibres into a potassium-based/metakaolin geopolymeric coating for architectural applications, with the dual objective of preventing environmental release and enhancing material performance. Geopolymer pastes containing 0.1–0.3 wt.% of synthetic microfibres were characterised in terms of physical, mechanical and microstructural behaviour. Microfibre addition produced a marked toughening effect, with flexural strength increasing from about 3 MPa for the unreinforced matrix to 7.5 MPa for the composite containing 0.3 wt.% fibres, while compressive strength decreased moderately due to the presence of a compliant fibrous phase. Microstructural observations confirmed fibre dispersion and fibre–matrix bonding, supporting crack-bridging mechanisms. Density, porosity and water absorption measurements indicated a stable geopolymer gel structure with a connected pore network. Thin-layer applications onto clay brick exhibited satisfactory workability and adhesion, confirmed by pull-off testing (~0.12 MPa) and interfacial microscopy. The results demonstrate that textile-derived microfibres can be effectively immobilised within a potassium geopolymer matrix while improving flexural performance, offering a feasible circular strategy for microfibre waste reuse in mineral coatings. Full article

This study investigates the tribological properties of 17-4PH martensitic stainless steel modified by plasma-based low-energy nitrogen ion implantation to enhance its surface hardness and wear resistance. The steel was nitrided at temperatures of 350 °C, 450 °C, and 550 °C for 4 h, and the resultant layers were characterized with respect to microstructure, hardness, and composition. Tribological tests were performed using a ball-on-disk tribometer under dry sliding conditions against an Si₃N₄ ceramic ball, with normal loads of 2–8 N and sliding speeds of 0.15–0.60 m/s. The results demonstrate that the nitrided layer thickness increased from 11 μm to 27 μm and the surface nitrogen concentration rose from 29.7 at.% to 33.1 at.% with increasing temperature, accompanied by an increase in nanocrystallite size from 2 nm to 15 nm and enhanced hardness from 13.51 GPa to 15.66 GPa. All nitrided layers exhibited significantly improved wear resistance relative to the unmodified steel. The layer nitrided at 450 °C demonstrated optimal performance due to a refined nanostructure and minor CrN that enhance plastic deformation resistance and facilitate oxide film formation. While, the 350 °C treated layer exhibits diminished thickness and reduced hardness, and the 550 °C treatment induces excessive CrN precipitation and micro-cracking, consequently compromising both toughness and wear resistance. Full article

Understanding the changes in physical and mechanical properties of lignite during dehydration is crucial for its sustainability in coal mining, exploitation of coalbed methane, and carbon dioxide sequestration. Through SEM and Computed Tomography (CT) scanning, combined with fractal theory, this study investigates dynamic dehydration characteristics of macerals in lignite during normal temperature drying (NTD), and their effects on pore–fracture development and physic–mechanical property evolution. The results show that the hard layers of lignite are mainly composed of ulminite (Ul), while the soft layers are primarily composed of fusinite (Fu), densinite (De), and Ul. Ul exhibits low dehydration efficiency but is prone to shrinkage and cracking heavily, whereas Fu has high dehydration efficiency and excellent thermal stability. The layered enrichment of macerals controls the development of the three-dimensional (3D) pore–fracture structures of lignite during NTD and leads to distinct cracking characteristics of fracture structures between hard and soft layers. Unlike soft layers, hard layers tend to form long, straight fracture structures with large apertures and exhibit extremely high fracture connectivity and fractal dimension (FD). In addition, the differential drying behavior of macerals causes the physical parameters of lignite such as moisture ratio (MR), drying rate (DR), and density (ρ) to show a dynamic evolution characteristic of “initial rapid decline (or increase) in the early stage–subsequent gradual decline (or increase) and stabilization in the later stage” during NTD. The unique pore–fracture structure controlled by macerals significantly alters the deformation resistance and failure mode of dehydrated lignite under uniaxial compression but has limited effect on its uniaxial compressive strength. Full article

Climate-driven extremes in temperature and precipitation are increasingly threatening the stability and serviceability of slopes, embankments, levees, transportation corridors, and other earthen infrastructures founded on expansive and problematic soils. Conventional stabilization strategies, which often treat reinforcement and drainage as separate design elements, struggle to cope with cyclic wetting-drying, freeze-thaw, and prolonged rainfall events that drive desiccation cracking, loss of matric suction, elevated pore-water pressures, and progressive strength degradation. This paper presents a state-of-the-art review of geosynthetic-reinforced slopes with particular emphasis on geogrid geotextile composite systems and their performance under high-temperature, high-rainfall, and low-temperature environments. We first summarize the fundamentals of geosynthetic types, functions, and material properties, then examine how thermal and hydrological processes such as creep, oxidation, frost heave, infiltration, suction loss, and pore-pressure build-up govern the performance of geosynthetic-reinforced soil (GRS) systems. Next, we synthesize recent advances in composite geosynthetics that integrate reinforcement, filtration, separation, and drainage, highlighting laboratory studies, centrifuge modeling, numerical analyses, and field case histories for mechanically stabilized earth walls, pavements, railway embankments, levee systems, and rainfall-induced and expansive soil slopes. Across these applications, geogrid geotextile composites consistently improve hydraulic control, maintain effective stress, and enhance factors of safety under extreme climatic loading. The review concludes by identifying critical research gaps, including coupled thermo-hydro-mechanical characterization, performance-based design approaches, and climate-resilient guidelines for geosynthetic selection and detailing. These findings underscore the potential of composite geosynthetics to enable more sustainable and resilient slope and earthwork infrastructure in a changing climate. Full article

Degraded non-cracking soils (locally known as Naga’a) are widespread in semi-arid regions of Sudan and are characterized by severe compaction, low organic matter, poor water retention, and limited crop productivity. Sustainable rehabilitation strategies for these soils remain underexplored. This study evaluated the potential of farmyard manure compost (FYM) as a soil amendment to improve physicochemical properties, soil water retention, and sorghum (Sorghum bicolor L.) performance in degraded Naga’a soil. Aerobic composting of FYM was conducted for two months under controlled moisture and C/N ratio conditions, producing a mature compost with enhanced organic carbon, nitrogen, and water-holding capacity. A pot experiment was conducted using five rates (0, 5, 10, 15, and 20 t ha⁻¹) of the produced compost alongside a mineral NPK treatment, assigned in a randomized complete block design. Compost application significantly (p ≤ 0.05) increased soil organic carbon, total nitrogen, total phosphorus, saturation percentage, and water-holding capacity compared with the control and NPK treatments. The highest compost rate (20 t ha⁻¹) improved soil water-holding capacity by approximately 20% and organic carbon by over 90% relative to the control. Sorghum dry matter production and plant nutrient uptake (N, P, K, and Ca) increased significantly with compost rate, while total seasonal irrigation water requirements declined. Water productivity improved progressively with compost addition, reaching a maximum increase of 60.5% at 20 t ha⁻¹ compared to the control. Overall, FYM proved effective in restoring soil functional properties, enhancing water-use efficiency, and improving sorghum growth. The results highlight the valorization of FYM as a sustainable, low-cost strategy for rehabilitating degraded non-cracking soils in arid and semi-arid environments. Full article

This study investigated the effects of varying water–binder (w/b) ratios and internal curing materials—superabsorbent polymer (SAP) and ceramsite—on the shrinkage behavior and crack resistance of ultra-high-performance concrete (UHPC). Although internal curing has been extensively studied, the comparative effectiveness of different internal curing materials on early-age shrinkage and restrained cracking behavior of UHPC under consistent mixture proportions remains unclear. To address this gap, a systematic experimental comparison of SAP and ceramsite was conducted. The influences of w/b ratio and different amounts and addition methods (dry and pre-absorbed addition) of SAP and ceramsite on the flowability, mechanical properties, early autogenous shrinkage, drying shrinkage, and early crack resistance of UHPC were discussed. Findings indicate that increasing the w/b ratio reduces autogenous shrinkage but compromises mechanical properties, altering the cracking mode from primary microcracks to a few wider cracks. Pre-saturated ceramsite (less than 10% volume) and SAP effectively mitigate autogenous and drying shrinkage, enhancing crack resistance without significantly reducing mechanical properties. However, exceeding a ceramsite volume dosage of 10% or using the dry addition method increased the flowability of UHPC, while decreasing crack resistance. Microstructural analysis reveals that internal curing materials facilitate hydration and enhance structural density through the formation of ettringite and calcium silicate hydrate. To optimize shrinkage reduction while maintaining mechanical properties, SAP should be incorporated in a dry state, with a dosage limited to 0.4% of the mass of the cementitious material; ceramsite needs to be pre-saturated and limited to 5% of the total volume. Full article