Search Results (111)

The long-term durability of repair systems combining normal concrete (NC) and ultra-high-performance concrete (UHPC) in marine environments depends on the response of the near-interface composite region to sequential carbonation and seawater exposure. However, the effects of seawater immersion following pre-carbonation remain insufficiently understood. This study compared an unexposed reference (REF), specimens carbonated for 28 d (C28), and specimens carbonated for 28 d and then immersed in simplified artificial seawater for 60 d (C28-SW60) using X-ray diffraction, thermogravimetry, backscattered electron imaging with energy-dispersive X-ray spectroscopy, and mercury intrusion porosimetry. Pre-carbonation promoted portlandite consumption, carbonate formation, and pore refinement. Subsequent seawater immersion further enhanced calcite-related diffraction and carbonate decomposition signals, while no typical crystalline salt-attack product was detected as dominant. The initial Ca-rich-to-Si-rich gradient from the NC side through the overlay transition zone to the UHPC side was accompanied by marked Cl accumulation and further S and Mg enrichment and redistribution. After seawater immersion, the measured total intrusion volume increased from 0.026 to 0.043 mL/g, the volume-based median pore-entry diameter increased from 27.49 to 58.42 nm, and the >1000 nm pore-volume fraction reached 39.82%, a change consistent with a shift toward coarser mercury-accessible pore entries. Together, the results link the initial heterogeneity of the NC–Overlay transition zone (OTZ)–UHPC region to a sequence-dependent response in which carbonate enrichment coexisted with multi-ion redistribution and transport-relevant defects, distinguishing carbonate accumulation from sustained near-interface refinement. Full article

Urban coastal cities face compounded flood hazards driven by sea-level rise, intense precipitation, and dense impervious surfaces. This study develops and demonstrates a cloud-native Python 3.12 GIS framework for flood susceptibility screening and critical facility exposure analysis in Miami, Florida, one of the most flood-exposed coastal cities in the United States. Defined here as a geospatial workflow that retrieves data dynamically from cloud-hosted APIs and executes entirely within a hosted computing environment, the framework integrates three open-source spatial indicators: terrain elevation from the USGS 3D Elevation Programme via py3dep; Euclidean distance to water bodies from OpenStreetMap via OSMnx; and building footprint density as an impervious surface proxy, also from OpenStreetMap. Indicators were standardised and combined using literature-informed MCDA weights (water proximity: 0.40; elevation: 0.35; building density: 0.25) into a continuous flood susceptibility index, classified at the 33rd- and 66th-percentile thresholds. In this proof-of-concept application, high-susceptibility zones cover 48.66 km² (34.0%) of the city, concentrated along coastal waterfronts and inland canal corridors. Overlaying critical facility locations on the classified surface indicates that 9 of 16 hospitals (56.2%), 61 of 244 schools (25.0%), and 5 of 17 fire stations (29.4%) fall within high-susceptibility zones; because this overlay uses centroid-based facility points that have not been cross-checked against official municipal or state facility registries, these counts should be read as indicative rather than definitive. Exact binomial testing shows that the school exposure deficit is statistically significant (p = 0.00), while elevated hospital exposure, although substantively notable, does not reach significance at the current sample size (p = 0.07). The susceptibility surface itself has not been quantitatively validated against external benchmarks such as FEMA flood maps or historical inundation records, the MCDA weights have not been sensitivity-tested, and spatial autocorrelation in the index has not been assessed; concrete protocols for each of these steps are specified as subsequent calibration work rather than as prerequisites for the architecture demonstrated here. The contribution of this paper is the reproducible, cloud-native workflow architecture and its proof-of-concept application, not a validated operational assessment tool; we present it explicitly as a methodological protocol and workflow demonstration, not as an evaluation of flood risk. The framework is fully reproducible, low-cost, and transferable to other US coastal cities. Full article

Asphalt bridge deck pavements are highly susceptible to rutting, shoving, and interlayer slippage under high-temperature traffic conditions, where interlayer shear stress plays a decisive role. To clarify the coupled effects of thermal gradients and moving loads, this study developed a sequential three-dimensional thermo-mechanical finite element model for a double-layer pavement in Zhongshan, China. Field-recorded air temperature, solar radiation, sunshine duration, and wind speed were used to define transient thermal boundaries. The calculated temperature field was then transferred to a fully bonded moving-load model with dual rectangular contact areas and braking-induced longitudinal traction. Axle load, roadway slope, braking coefficient, and the thicknesses of the SMA-13 and AC-20 layers were varied. The predicted temperature fluctuation attenuated and the peak time was delayed with depth. The pavement surface reached 58.95 °C at 13:00, whereas the bottom of the asphalt overlay reached 46.99 °C at 17:00. Under the adopted 14:00 near-peak summer condition, increasing axle load amplified the overall response and raised the maximum asphalt-layer shear response from 0.172 to 0.223 Mpa. Roadway slope mainly affected traffic-direction stress transfer. Increasing the braking coefficient from 0 to 0.7 increased longitudinal shear response from 57.9 to 161.2 kPa in the asphalt layers and from 56.4 to 112.6 kPa near the AC-20/concrete interface. Increasing SMA-13 thickness reduced thermal and mechanical demand in the underlying layers, whereas increasing AC-20 thickness reduced the response near the concrete deck but shifted part of the tensile and shear demand toward the upper asphalt layer. Full article

Single-story unreinforced masonry rural houses along the Tanlu Earthquake Belt in Anhui Province are generally constructed without ring beams and tie columns, resulting in poor structural integrity and low seismic performance. This paper proposes a convenient single-sided High-Ductility Concrete Strip (HDCS) retrofitting method. Two 1:2 scaled test specimens, namely the unretrofitted model M1 and HDCS single-side retrofitted model M2, were fabricated for shaking table tests. Systematic analyses were carried out based on white noise sweep tests, failure modes, acceleration responses and inter-story displacement responses. The test results show that HDCS possesses excellent tensile capacity, which forms continuous confinement at wall joints and openings to boost structural stiffness and greatly restrain post-seismic stiffness degradation, as well as achieve more uniform structural deformation distribution. Under strong seismic excitations, the unretrofitted model suffers severe damage, including penetrating diagonal shear cracks and separation between gable walls and lower walls. In contrast, damage of the retrofitted model is concentrated within the HDCS overlay, realizing damage redistribution and preventing brittle failure of the main masonry. HDCS stabilizes the distribution of acceleration amplification factors and restrains wall rocking and stress concentration around openings. Although single-sided strengthening induces slight out-of-plane effects, its adverse influence is acceptable. Full article

A comprehensive bibliometric analysis of zeolite in concrete was conducted using VOSviewer software (version 1.6.21). The database was obtained from Scopus by searching for zeolite in concrete. A filter for the years 2000 to 2025 was applied. A total of 1001 documents related to zeolite concrete fulfilled the criteria and were downloaded. The co-occurrence networks and overlay technique were utilized to illustrate relationships. The publication trends, publication area, document types, and country-wise publications were considered for analysis. Also, the top universities/institutions and funding sources that supported zeolite in concrete-related research were considered. Furthermore, keyword analysis was used to find the past, current, and future research trends. The findings highlight the increasing importance of zeolite-based concrete, particularly from 2015 to 2024. Engineering accounted for the largest publication base, with 614 articles. Research articles represented the predominant document type, with a total of 664 publications. In contrast, only 40 of the 1001 articles are full-length review papers. The country-wise analysis indicates that Iran (163) and China (146) are at the top in scientific contributions. The keyword analysis indicates that most researchers focus on “Zeolite,” “Concrete,” “Compressive Strength,” and “Durability”. The bibliometric analysis further reveals a clear shift in zeolite-concrete research toward sustainability applications focused on durability, geopolymer, and self-compacting concrete. In addition, the study identifies several underexplored research themes, including shrinkage, creep, life-cycle assessment, and artificial intelligence-based mix optimization. The findings provide a research roadmap for advancing the next generation of sustainable zeolite-based concrete. Full article

This study presents a laboratory-scale assessment of heat-assisted fly ash-based geopolymer concrete as a potential thin protective layer in one asphalt–geopolymer pavement configuration. The programme comprised water penetration under pressure, abrasion, initial skid resistance, wheel tracking, four-point-bending fatigue, mechanical strength, freeze–thaw response, de-icing-salt scaling, thermal characterization, and qualitative scanning electron microscopy. The selected geopolymer reached mean flexural, compressive, and splitting tensile strengths of 10.756, 61.058, and 3.797 MPa, respectively. Final rut depths were 1.57 mm after 7 days and 0.72 mm after 28 days, with corresponding WTSAIR values of 0.020296 and 0.014238 mm per 10³ cycles. After 10⁶ cycles at 10 Hz, 72–85% of the initial stiffness modulus remained across the tested strain levels. Mean de-icing-salt scaling was 0.500 kg/m² after 28 days and 0.995 kg/m² after 56 days. Standalone geopolymer specimens underwent full-depth water penetration, whereas no leakage through the asphalt layer was observed in the intact layered specimen during the 5 bar, 72 h test. This system-level observation supports functional tightness only under the tested intact condition and does not establish intrinsic material impermeability or long-term interface durability. Interpretation is limited to this laboratory-scale configuration: the 90 °C heat-assisted curing protocol limits transfer to conventional in situ paving; no ambient- or standard-cured control and no same-condition conventional overlay control were included; and only one composite geometry was evaluated. The findings therefore define application boundaries for further validation rather than a field-ready specification or proof of comparative superiority. Full article

[¹⁸F]-PSMA PET/CT is a high-impact modality for the staging and restaging of prostate cancer, but its wide anatomic coverage and tracer biology generate frequent incidental findings on both PET and the accompanying low-dose CT (LDCT). This narrative review is restricted in scope to fluorine-18 PSMA tracers because tracer-specific biodistribution and pitfall profiles shape what is perceived as incidentaloma: how confidently lesions can be categorized, and how often borderline findings trigger downstream testing, particularly for skeletal foci with [¹⁸F]-PSMA-1007. Specifically, [¹⁸F]-PSMA-1007 shows substantially higher rates of focal unspecific bone uptake than [⁶⁸Ga]-PSMA-11—reported in multicenter studies as affecting up to 40–50% of patients—which directly inflates the pool of potential incidentalomas and creates a tracer-specific false-positive problem with no parallel in gallium-68 practice. Additionally, [¹⁸F]-DCFPyL has different urinary clearance kinetics that affect bladder and ureteral uptake patterns, altering what qualifies as physiologic versus incidental in the pelvis. These differences mean that the threshold for Category B versus C classification—and the appropriate cascade-resistant language—must be tuned to the specific tracer in use. A framework built on [⁶⁸Ga]-PSMA-11 data would systematically underestimate bone pitfall frequency in [¹⁸F]-PSMA-1007 practice and could therefore paradoxically increase rather than reduce cascades if applied uncritically across tracers. These biodistribution differences have direct and concrete consequences for reporting behaviour and downstream management. In [¹⁸F]-PSMA-1007 practice, a focal bone uptake without a CT correlate in a mechanically plausible location—such as an anterior rib or vertebral endplate—should trigger Category B language in the report conclusion: the finding is documented in the body with explicit safety netting (“most consistent with unspecific uptake; no routine workup unless interval growth, new pain, or aggressive CT morphology”), and no referral to bone scintigraphy or MRI is generated. Without tracer-specific awareness, the same finding would typically prompt a reflex bone scan or whole-body MRI referral, delaying definitive prostate cancer management by weeks and adding imaging costs without diagnostic gain. By contrast, in [⁶⁸Ga]-PSMA-11 practice, an equivalent focal bone uptake without a CT correlate carries a higher prior probability of true metastatic disease given the lower background rate of unspecific uptake and should more often be reported at Category B with a lower threshold for escalation or more cautious language. For [¹⁸F]-DCFPyL, the higher urinary activity in the pelvis means that ureteral segments can mimic lymph node disease; recognizing this as a physiologic variant (Category C) rather than an equivocal nodal finding (Category B) avoids unnecessary pelvic MRI referrals that would otherwise be triggered by an uncontextualized report. In practical terms, the tracer-specific calibration of the overlay therefore changes not only the category assigned but also the specific safety-netting language and the escalation trigger, which directly modifies the downstream management pathway for each affected finding type. The scanned population—predominantly older men with a high prevalence of degenerative, inflammatory, and vascular abnormalities—creates substantial background noise that can drive low-value diagnostic cascades if incidental findings are communicated without actionability context. We integrate society-endorsed frameworks (EANM/SNMMI procedure guideline 2.0; E-PSMA; PSMA-RADS; and PROMISE/miTNM with miPSMA score) and propose a cascade-aware overlay for incidental findings that can be appended to existing PSMA reporting standards rather than replacing them. The A/B/C actionability overlay is a structured expert-consensus framework informed by existing evidence-based guidelines for specific finding types and by tracer-specific cohort data; it has not yet been prospectively validated as a standalone tool, and its current level of evidence is therefore analogous to a structured expert recommendation rather than an evidence-based clinical guideline. We operationalize a three-tier actionability scheme across PET- and CT-dominant findings, provide cascade-resistant language for conclusions, and clarify why SUVmax-only “probability scales” for lymph nodes are not recommended in routine reports. Three practical tables summarize PET incidental findings, lymph node reporting frameworks, and LDCT incidental findings, and two structured report templates are provided (concise and extended), with the extended version explicitly labelling actionability tiers and escalation triggers. Finally, we outline concrete AI use cases for standardization and triage while emphasizing governance to avoid the amplification of false positives and paradoxical growth of cascades. Full article

Against the backdrop of rural revitalization, traditional ethnic minority villages in Guizhou face the dual challenges of conservation and development. Existing research has largely focused on macro-scale morphological descriptions, lacking an operational spatial classification method that can directly guide planning and management. To address this gap, this paper takes Fengxi Village in Dejiang County as a case study, integrates Conzenian urban morphology with the concept of “management units”, and proposes a spatial unit classification method for traditional villages based on the overlay analysis of “morphological region + building unit”. First, using Conzenian plan analysis, the study systematically deconstructs land use, road systems, plot combinations, and building types of Fengxi Village to delineate morphological regions. Second, it introduces three evaluation factors—building value, building quality, and building style—and, through quantitative assessment, classifies all 702 buildings in the village into five categories, protection units, repair and improvement units, comprehensive renovation units, demolition and renewal units, and new construction units, with the number and proportion of each category calculated. On this basis, differentiated control guidelines and development strategies are proposed for each unit category. The research shows that this method represents a preliminary attempt to translate “morphological description” into “operational control”, breaking down the relatively macro goal of “integral conservation” into concrete “unit-based control” actions, thereby providing a technical workflow that can be referenced for similar studies on the fine-grained planning and management of traditional villages. The main contribution of this paper is the construction of a systematic technical framework of “morphological analysis–factor evaluation–unit-based control”, and the demonstration of its application at the micro-operational level through the Fengxi Village case study, offering a meaningful complement to the existing research in terms of operationalization. Full article

Nano-silica (nano-SiO₂) has emerged as a powerful designer tool for engineering the microstructure of geopolymer composites, enabling precise control over porosity, interfacial transition zone (ITZ) characteristics, and resultant mechanical performance. The main aim of this review is to evaluate the role of nano-silica as a reinforcement and pozzolanic accelerator. The paper delivers a critical literature overview. It is based on a comprehensive critical review of the existing literature and illustrative case studies demonstrating practical applications in geopolymer composites. The article presents the key mechanisms connected with the application of nano-additives, including accelerated geopolymerization kinetics and heterogeneous nucleation on nano-silica surfaces. Comprehensive characterization methods are critically assessed, including SEM/EDS for gel morphology, MIP for porosity profiles, XRD/FTIR for reaction products, micro-CT for 3D void networks, and nanoindentation for ITZ mechanical gradients. The article also shows the main applications span high-performance concretes, 3D-printed geopolymer elements (improved buildability and interlayer adhesion), and durable overlays. The article is a closed presentation of challenges such as long-term stability, alongside future directions. The main findings show that nano-silica offers a pathway to tailored, low-carbon geopolymers with superior microstructure–performance relationships aligned with sustainable construction goals. Full article

The application of ultra-high performance concrete (UHPC) in the hogging moment region significantly enhances the crack resistance of concrete slabs of composite girders with integrated piers, while also providing economic benefits. To investigate the crack resistance performance and develop a calculation method for crack width in hogging moment region of steel–UHPC–normal concrete (NC) composite girders, a full-scale bending test was conducted. Based on the test results, the post-cracking residual tensile strength of UHPC was determined according to the energy equivalence principle. A calculation method for reinforcement stress incorporating the tensile contribution of UHPC at a cracked section was proposed and then the applicability for current design codes for crack width calculation was evaluated. For the UHPC–NC interface, a corresponding crack width calculation method was developed. The results indicate that cracks initiated on the surface of the NC layer beneath the UHPC overlay at the cantilever root. Then cracks developed in sequence at the top surface of the UHPC layer cantilever root, the UHPC–NC interface, and the mid-plane of the girder-to-pier joint. Ultimately, UHPC cracks exhibited a “numerous and closely spaced” distribution, whereas NC cracks were “few and widely spaced.” When the residual tensile strength of UHPC at cracked section was considered, the mean value and average coefficient of variation in the ratios of calculated to measured reinforcement stresses for different sections were 1.07 and 0.10, respectively, which can be further used for crack width calculation. The mean ratios of code-predicted to measured UHPC crack widths for different sections using the Chinese code, French code, and European code were 1.10, 0.98, and 1.13, respectively, with corresponding average coefficients of variation of 0.25, 0.33, and 0.28; the Chinese code is recommended for UHPC crack width prediction. For the UHPC–NC interface, an expression for crack width calculation was derived using the comprehensive theory, and the mean ratio of calculated to measured values and the coefficient of variation were 1.08 and 0.18, respectively, demonstrating good predictive accuracy. Full article

This study proposes a lightweight crack-segmentation model optimized for industrial and edge-computing environments, where both high accuracy and real-time inference are required. Conventional convolution-based and U-Net-based crack segmentation models offer relatively simple architectural designs, but often suffer from limited boundary precision or an unfavorable accuracy–efficiency trade-off. Swin Transformer-based approaches can model broader contextual information but may still show poor segmentation quality relative to their computational cost in fine crack analysis. To address these limitations, we propose the Stabilized Crack Network++ (SCN++), a U-Net backbone crack segmentation network that integrates edge fusion, hybrid loss with deep supervision, exponential moving average (EMA)-based stabilization, and lightweight post-processing. The model was trained and evaluated on 40,000 concrete surface images, including 20,000 crack images and 20,000 non-crack images, using quantitative metrics such as intersection over union (IoU), Dice coefficient, frames per second (FPS), giga floating-point operations (GFLOPs), and the number of parameters, together with overlay-based qualitative analysis. Compared with the CNN, U-Net, and Swin Transformer baselines, SCN++ achieved the best overall balance between segmentation accuracy and computational efficiency, with an IoU of 0.7346, a Dice coefficient of 0.8457, 35.09 FPS, 8.45 GFLOPs, and only 2.22 M parameters. These results demonstrate that SCN++ effectively mitigates the conventional accuracy–efficiency trade-off and is a strong candidate for practical structural crack segmentation in edge-computing environments. Full article

The preventive maintenance (PM) of asphalt pavements reduces life-cycle costs and minimizes resource consumption compared with reactive rehabilitation, yet its cost-effectiveness is highly sensitive to application timing. This study develops a data-driven framework for determining optimal PM timing on Korean expressways by integrating network-level pavement management system (PMS) deterioration modeling with life-cycle cost analysis (LCCA). Using 10-year PMS time-series data from approximately 2200 asphalt pavement sections (2012–2021), a nonlinear regression of the Highway Pavement Condition Index (HPCI) yielded an exponential deterioration model with exponent β = 1.87 (R² = 0.996), confirming accelerating deterioration beyond a critical service age. The HPCI inflection coincides with the Grade-2 boundary (3.5–4.0), where surface distress growth—dominated by linear cracking (91.3% of total SD)—also peaks. A LCCA across 44 scenarios demonstrated that PM applied immediately before this acceleration onset minimizes the 40-year net present value (NPV; discount rate 4.5%). The optimal first PM application time was estimated at 10.8 years (≈56% of the 19.3-year average service life), reducing the 40-year NPV by up to 7 million KRW per section relative to the milling and overlay baseline (up to 16 million KRW in absolute NPV terms for concrete overlay sections). These findings provide a quantitative, reproducible basis for PM timing decisions applicable to the approximately 4000 km of expressway pavement managed by Korea Expressway Corporation. Full article

Composite specimens of normal concrete (NC) and ultra-high performance concrete (UHPC) in marine tidal zones are susceptible to coupled physico-chemical degradation under seawater wet–dry cycling; however, the microscopic damage-evolution mechanisms within the NC/overlay transition zone (OTZ)/UHPC three-phase region remain unclear. In this study, accelerated erosion was conducted using 10-fold concentrated artificial seawater under 0, 30, 60, and 90 wet–dry cycles. The X-ray computed tomography, mercury intrusion porosimetry, backscattered electron imaging coupled with energy dispersive X-ray spectroscopy and slant shear tests were employed to systematically investigate the macroscopic bonding performance and microscopic structural damage of NC-UHPC composites. The results show that the interfacial bond strength initially increases and then declines, exhibiting a 13.53% improvement after 30 wet–dry cycles and a sharp 41.55% decrease after 90 cycles compared with that after 60 cycles. The damage severity was the highest in NC, intermediate in OTZ, and lowest in UHPC. The gas-rich pore region within the OTZ provides a stress-buffering effect during the early stage of corrosion. After 90 wet–dry cycles, the total porosity increased by 0.14%, with external porosity increasing by 0.21% and internal porosity decreasing by 0.07%, indicating a pore-structure reconfiguration characterized by micropore coalescence and an increased proportion of macropores. These findings clarify the damage process associated with seawater erosion, pore expansion, and interfacial failure, providing theoretical support for the repair design and durability assessment of marine concrete structures. Full article

The strengthening of reinforced concrete (RC) beams requires repair systems that can enhance strength, stiffness, and energy dissipation without significantly increasing self-weight or compromising durability. This study explores the structural response of RC beams strengthened using an integrated shear–flexure system combining near-surface-mounted carbon fiber-reinforced polymer (NSM-CFRP) ropes and steel-reinforced geopolymer overlays in the compression zone. Monotonic three-point bending tests were performed on two RC beam specimens, one unstrengthened control and one strengthened beam, to obtain preliminary observations of load–deflection behavior, stiffness, ductility, and energy absorption. The strengthened specimen exhibited increases in ultimate load (28.6%), stiffness (13.6%), and energy absorption (7.65%) relative to the control beam, suggesting the potential for effective composite action between the CFRP ropes and geopolymer material. A three-dimensional nonlinear finite element model was developed using ATENA to support interpretation of the experimental response, incorporating detailed constitutive models for concrete, steel reinforcement, and CFRP ropes. The numerical predictions showed reasonable agreement with the experimental results. Within the limitations of the test matrix, the results indicate that the proposed dual strengthening system may offer a viable and sustainable approach for enhancing the shear–flexural performance of RC beams. Full article

This study provides computational insights into the flexural strengthening of reinforced concrete (RC) T-beams in the negative moment region using steel-reinforced polymer cement mortar (PCM) overlays. A validated three-dimensional nonlinear finite element (FE) model was developed using the Advanced Tool for Engineering Nonlinear Analysis (ATENA) software (version 2023.0.0.22492) to simulate the behavior of beams retrofitted with 40 mm thick PCM layers embedded with 13 mm and 16 mm deformed bars. Model validation was performed against previously published experimental results reported by the authors, demonstrating excellent agreement, with normalized mean square error (NMSE) values expressed as fractions between 0.0001 and 0.0022, and experimental-to-numerical ultimate load ratios ranging from 0.99 to 1.01. Parametric analyses were then conducted to investigate the influence of key variables, concrete compressive strength, PCM overlay thickness, and longitudinal reinforcement ratio on the global flexural performance. The results revealed that increasing the overlay thickness raised the ultimate load capacity by up to 15.4% and improved energy absorption by 43%. Enhancing concrete strength led to gains of up to 12.5% in load capacity and 15.8% in stiffness. Variations in reinforcement ratio had the most significant impact, increasing peak load by up to a factor of 2.02 and improving energy absorption by up to a factor of 1.49. Despite these improvements, reductions in ductility were observed across all strengthening configurations, underscoring a strength–deformability trade-off critical for seismic applications. These findings affirm the efficacy of steel-reinforced PCM overlays and provide design-oriented insights for optimizing negative moment retrofitting strategies in RC bridge girders and continuous beam systems. Full article