Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Dokumenttyp
- Zeitschriftenartikel (183) (entfernen)
Sprache
- Englisch (155)
- Deutsch (27)
- Portugiesisch (1)
Schlagworte
- Corrosion (21)
- KorroPad (13)
- Nichtrostender Stahl (12)
- Korrosionsschnelltest (11)
- Passivschicht (11)
- Cement (10)
- Korrosion (8)
- Rheology (8)
- Additive manufacturing (7)
- Rubber (7)
- Alkali-activated materials (5)
- Carbon steel (5)
- Concrete (5)
- Durability (5)
- Flame retardant (5)
- Graphene (5)
- Microstructure (5)
- Compressive strength (4)
- Corrosion testing (4)
- Degradation (4)
- Hydration (4)
- Impurities (4)
- Mechanical properties (4)
- Nanocomposites (4)
- Portland cement (4)
- Stainless steel (4)
- Adsorption (3)
- Alkali-Kieselsäure-Reaktion (3)
- Betonfahrbahndecke (3)
- Betonfahrbahndecken (3)
- Bitumen (3)
- Cement hydration (3)
- DFG SPP 2005 (3)
- EPR (3)
- FTIR (3)
- Geothermie (3)
- Grinding (3)
- Nanocomposite (3)
- Pitting corrosion (3)
- Polyethylene (3)
- Polymers (3)
- Polymers of intrinsic microporosity (3)
- UV radiation (3)
- Weathering (3)
- AKR (2)
- Ageing (2)
- Al2O3 (2)
- Alloy 31 (2)
- Aluminium (2)
- Anlagensicherheit (2)
- Anwendungsmöglichkeiten (2)
- Arbeitsanleitung (2)
- Artificial weathering (2)
- Austenitic stainless steel (2)
- Automated expansion measurement (2)
- Basic oxygen furnace slag (2)
- Bitumen und bitumenhaltige Bindemittel (2)
- Boson peak (2)
- CCUS (2)
- Carbon dioxide (2)
- Cement paste (2)
- Ceramics (2)
- Characterization (2)
- Coating (2)
- Condensate (2)
- Copper (2)
- Corrosion rate (2)
- Corrosion resistance (2)
- Crosslinking (2)
- Depletion force (2)
- EPDM (2)
- Earth block masonry (2)
- Elastomers (2)
- Electrical conductivity (2)
- Engineered recycled mineral admixtures (2)
- Environmental stress cracking (ESC) (2)
- FTIR-Spektroskopie (2)
- Fire (2)
- Fracture (2)
- Full notch creep test (FNCT) (2)
- Gas separation membranes (2)
- Gel electrolytes (2)
- Geothermal energy (2)
- Heat treatment (2)
- High-density polyethylene (2)
- Hyperbranched (2)
- Laser scanning microscopy (LSM) (2)
- Laser-induced slip casting (2)
- Legierungen (2)
- MIC (2)
- Microbially induced corrosion (2)
- Moisture (2)
- Moisture content (2)
- Molecular mobility (2)
- Multilayer graphene (2)
- Natural rubber (2)
- Neutron scattering (2)
- Nitric acid (2)
- Polyaniline (2)
- Polysaccharides (2)
- Polyurethane (2)
- Präzision (2)
- Qualitätssicherung (2)
- Relative humidity (2)
- Sr isotopes (2)
- Steel (2)
- Steel corrosion (2)
- Structural sealant glazing (2)
- Superplasticizer (2)
- Synthesis (2)
- Thermal analysis (2)
- Thermal treatment (2)
- UHPC (2)
- ZfP (2)
- Zinc coatings (2)
- 1H-NMR (1)
- 3-dimensional microscopy (1)
- 60 °C-Betonversuch (1)
- ASR (1)
- ASR modelling (1)
- Abrasive belt (1)
- Accelerated concrete prism test (1)
- Accelerated temporal integration (1)
- Accelerated test (1)
- Accelerated testing (1)
- Acid resistance (1)
- Active thermography (1)
- Admixture (1)
- Advanced calorimetry (1)
- Agar (1)
- Ageing behaviour (1)
- Ageing treatment (1)
- Aging (1)
- Agricultural by-product (1)
- Aktiv-Passiv-Element (1)
- Al-Composite (1)
- Al/SiO2 composite (1)
- Alkali silica reaction (1)
- Alkali-activated slag (1)
- Alkali–silica reaction (1)
- Alternative materials (1)
- Aluminum hydroxide (ATH) (1)
- Ambient vibration measurements (1)
- Analytical methods (1)
- Anisotropy (1)
- Antioxidant additives (1)
- Aquifer fluid (1)
- Aromatic (1)
- Asphalt (1)
- Asphalt oxidation (1)
- Atmospheric corrosion (1)
- Atmospheric exposure (1)
- Atmosphärische Korrosion (1)
- Auslaugung (1)
- Automatische Dehnungsmessung (1)
- Açaí fiber (1)
- BOFS (1)
- Bacterial attachment (1)
- Baustoffe (1)
- Behmite (1)
- Belüftungselement (1)
- Beton (1)
- Bimetallkorrosion (1)
- Binary zinc alloys (1)
- Binder aging (1)
- Binder chemistry (1)
- Binder rheology (1)
- Bio-based concrete (1)
- Biodiesel (1)
- Biofilm (1)
- Biogene Schwefelsäurekorrosion (1)
- Biogenic acid corrosion (1)
- Bioreceptivity (1)
- Brass (1)
- Broadband Dielectric Spectrscopy (1)
- Bruchlastwechselzahlen (1)
- Building Materials (1)
- Building and Construction (1)
- Building with earth (1)
- C&D waste (1)
- CCS (1)
- CCUS, supercritical/dense phase CO2, carbon steels, martensitic steel, superaustenite steel, droplet corrosion (1)
- CO2 pipeline transport (1)
- CO2 quality (1)
- Cable (1)
- Calcination (1)
- Calcined clay (1)
- Calcium Cobaltite (1)
- Calcium sulfoaluminate (CSA) cement (1)
- Calcium sulfoaluminate cement (1)
- Carbon black (1)
- Carbon capture (1)
- Carbon capture storage (1)
- Carbon capture, utilization and storage technology (1)
- Carbon dioxide emissions (1)
- Carbon footprint (1)
- Casing (1)
- Cavitation (1)
- Cement-based composites (1)
- Characterisation (1)
- Charakterisierung (1)
- Charge density (1)
- Chemical admixtures (1)
- Chemometrie (1)
- Circular economy (1)
- Civil and Structural Engineering (1)
- Climate (1)
- Cob (1)
- Compatibility (1)
- Compressed earth (1)
- Compression behavior (1)
- Compression tests (1)
- Computed tomography (1)
- Concrete Prism Test at 60 °C (1)
- Condensed Matter Physics (1)
- Cone calorimeter (1)
- Contact angle (1)
- Corrosion costs (1)
- Corrosion inhibitor (1)
- Corrosion protection (1)
- Corrosivity category (1)
- Covalent Organic frameworks (1)
- Crack opening displacement (1)
- Cracks (1)
- Crevice corrosion (1)
- Critical chloride content (1)
- Critical pitting temperature (1)
- Crop protection products (1)
- Crystal Texture (1)
- Crystalline admixture (1)
- Cyclic reuse (1)
- DLO (1)
- DOPO (1)
- Damage analysis (1)
- Data infrastructures (1)
- Dealloying (1)
- Decarbonisation (1)
- Defect detection (1)
- Demolition wastes (1)
- Desiccation (1)
- Developing building materials (1)
- Dielectric spectroscopy (1)
- Diesel (1)
- Diesel Fuel (1)
- Digital Volume Correlation (1)
- Digital image correlation (1)
- Digital representations (1)
- Digital workflows (1)
- Disinfectants (1)
- Dissolution (1)
- Drinking water (1)
- Druckschwellenversuch (1)
- Durability testing (1)
- Dye (1)
- Earth block (1)
- Earth blocks (1)
- Earth masonry (1)
- Earth mortar (1)
- Education (1)
- Effective properties (1)
- Electrochemical characterisation (1)
- Electrochemical deposition (1)
- Electrochemical methods (1)
- Electrochemical potentiodynamic reactivation (1)
- Electrochemical potentiokinetic reactivation (1)
- Elektrochemie (1)
- Energy systems (1)
- Environment (1)
- Environmental Chemistry (1)
- Environmental Stress Cracking (1)
- Environmental benefits (1)
- Environmental stress cracking (1)
- Enzymatic degradation (1)
- Ermüdungsverhalten (1)
- Explosion (1)
- Explosive spalling (1)
- FAIR data (1)
- FT-IR (1)
- Fast Scanning Calorimetry (1)
- Fast measurement (1)
- Fast scanning calormetry (1)
- Fatigue (1)
- Feuchtemessung (1)
- Fiber-reinforced composite (1)
- Finite-element method (1)
- Fire behavior (1)
- Fire spalling (1)
- Flame retardancy (1)
- Flue gas desulphurisation facilities (1)
- Fluidity (1)
- Fluorescence (1)
- Fourier series (1)
- Fracture surface analysis (1)
- Fracture surfaces (1)
- Free polymer (1)
- Free weathering (1)
- Friction (1)
- Frost salt attack (1)
- Fuel sorption (1)
- Full Notch Creep Test (1)
- Full notch creep test (1)
- Future‑oriented standards (1)
- GMR sensors (1)
- Gas permeability (1)
- Gas separation (1)
- Gel-type electrolytes (1)
- Gelartige Elektolyte (1)
- General Materials Science (1)
- Geothermal (1)
- Gradient-enhanced fatigue model (1)
- Green facades (1)
- Green urban construction (1)
- Green-Death solution (1)
- Grooving (1)
- Growth defects (1)
- Gutachten (1)
- Hardly separable problem (1)
- Heated concrete (1)
- High density polyethylene (1)
- High-performance concrete (1)
- Highly permeably polynorbornenes (1)
- High‐nitrogen steel (1)
- Humidity (1)
- Hydration kinetics (1)
- Hydration products (1)
- Hydration stoppage (1)
- Hydrogarnet (1)
- Hydrothermal treatment (1)
- Hydroxylellestadite (1)
- Hysteresis measurement (1)
- ISO 9223 (1)
- Identifizierung von Additiven (1)
- Impact loading (1)
- Impacts (1)
- In-Situ X-ray CT (1)
- In-situ ED-XRD (1)
- Inelastic neutron scattering (1)
- Initial shear strength (1)
- Innenhydrophobierung (1)
- Inorganic polymers (1)
- Interlaboratory test (1)
- Internal Surfaces (1)
- Ionic stregth (1)
- Iron ore tailings (1)
- Iron speciation (1)
- Iron–chromium–nickel alloy (1)
- Irradiation (1)
- Knowledge graphs (1)
- Konzentrationselement (1)
- Korrosionsprüfung (1)
- Korrosionsschutz (1)
- Korund (1)
- Kupferazid (1)
- LIBS (1)
- Lattices (1)
- Layered double hydroxide (1)
- Leaching of alkalis (1)
- Lead (1)
- Lean duplex (1)
- Limestone powder (1)
- Lithium (1)
- Lithium aluminosilicates (1)
- Load-bearing behaviour (1)
- Lochkorrosion (1)
- Long-term storage (1)
- Low carbon steel (1)
- Low-carbon construction (1)
- Low-cement concrete (1)
- Lunar regolith (1)
- MCC (1)
- MRFA (1)
- Magnesium (1)
- Magnetic stray field (1)
- Mapping for unseparable load (1)
- Marble deterioration (1)
- Marble sculptures (1)
- Marine atmosphere (1)
- Martensitic stainless steel (1)
- Martensitic steel (1)
- Martensitic steels (1)
- Masonry (1)
- Masonry tower (1)
- Mass loss (1)
- Material failure (1)
- Material properties (1)
- Materialkennwerte (1)
- Materials (1)
- Materials Chemistry (1)
- Materials informatics (1)
- Materialuntersuchung (1)
- Mechanical Engineering (1)
- Mechanical deformation (1)
- Mechanical strength (1)
- Mechanics of Materials (1)
- Membrane polymers (1)
- Metadata (1)
- Metals and Alloys (1)
- Method development (1)
- Methyl group rotation (1)
- Micro-CT scanning (1)
- Microplastic (1)
- Microporous polymers (1)
- Middle Pleistocene (1)
- Mining tailing (1)
- Mining tailings (1)
- Mitigation strategies (1)
- Model calibration (1)
- Model order reduction (1)
- Model order reduction (MOR) (1)
- Model tuning (1)
- Modulus of elasticity (1)
- Moisture transport (1)
- Molecular mass distribution (1)
- Multiple reuse (1)
- Multivariate Analysemethoden (1)
- Multivariate analysis methods (1)
- NBR (1)
- Nanoparticles (1)
- Nanosilica (NS) (1)
- Nasschemie (1)
- Natural fibers (1)
- Network (1)
- Neutron Scattering (1)
- Neutron diffraction (1)
- Non-destructive testing (1)
- Nonferrous slag (1)
- Nuclear Magnetic Resonance (1)
- Oberflächentexturierung (1)
- Ontologies (1)
- Optical criterion of brittleness (1)
- Organophosphonate (1)
- Orientation distribution (1)
- Outdoor weathering (1)
- Oxyfuel (1)
- PCE (1)
- PCE-Based superplasticizer (1)
- PE-HD Sorption (1)
- PVD hard coating (1)
- Packaging (1)
- Packing density (1)
- Passive film (1)
- Passivity (1)
- Penetration test (1)
- Pentaerythritol (1)
- Performance assessment (1)
- Phase development (1)
- Phosphine oxide (1)
- Phosphorous flame retardant (1)
- Phosphorus (1)
- Photoluminescence (1)
- Photooxidation (1)
- Physical aging (1)
- Physical vapour deposition (PVD) (1)
- Pinholes (1)
- Pipeline network (1)
- Pitting (1)
- Plasticity (1)
- Polarisation (1)
- Poly(L‑lactide) (1)
- Poly(N-vinylpyrrolidone) (1)
- Poly(vinyl chloride) (1)
- Polybutadiene/chloroprene (1)
- Polycarboxylate superplasticizer (1)
- Polycarboxylate superplasticizers (PCE) (1)
- Polyesters (1)
- Polymer of intrinsic microporosity (1)
- Polymer of intrisic microporosity (1)
- Polymers of Intrinsic Microporosity (1)
- Polymers with intrinsic microporosity (1)
- Polynorbornenes (1)
- Polynorbornes (1)
- Polyolefins (1)
- Polyphosphate (1)
- Polyphosphoester (1)
- Polypropylene fiber (1)
- Polyvinyl alcohol fiber (1)
- Pore solution (1)
- Portland clinker (1)
- Potassium ions (1)
- Potentiometry (1)
- Preventive strategies (1)
- Probekörpergeometrien (1)
- Proper generalized decomposition (1)
- Proper generalized decomposition (PGD) (1)
- Protection (1)
- Provenance (1)
- Provenancing (1)
- Prüfverfahren (1)
- Quality assurance (1)
- Quartzite mining tailing (1)
- Quasielastic neutron scattering (1)
- Radar (1)
- Raman spectroscopy (1)
- Rammed earth (1)
- Reaction-sintering (1)
- Recommendations (1)
- Recyclable (1)
- Recycled aggregate (1)
- Recycled materials (1)
- Recycled mineral admixture (1)
- Recycling (1)
- Reflection spectroscopy (1)
- Reinforced concrete (1)
- Rejuvenator (1)
- Reproducible data processing (1)
- Residual stress (1)
- Resistance (1)
- Resource (1)
- Resting time (1)
- Retardation (1)
- Rheological (1)
- Rheological properties (1)
- Rheological property (1)
- Rheometry (1)
- Rice husk ash (1)
- Rigid (1)
- Road pavement (1)
- SHCC (1)
- Sample holder (1)
- Sample piece size (1)
- Sand-lime block (1)
- Scanning acoustic microscopy (SAM) (1)
- Schadensanalyse (1)
- Schleifen (1)
- Scientific workflows (1)
- Self-healing (1)
- Semantic web (1)
- Semiconductive layer (1)
- Sensitisation (1)
- Sensitivity (1)
- Sensitivity analysis (1)
- Shear behavior (1)
- Shear bond test (1)
- SiO2 Nanoparticle (1)
- Silica (1)
- Silicone elastomer (1)
- Sintering (1)
- Sisal fiber (1)
- Slag (1)
- Slow crack growth (SCG) (1)
- Soaking time (1)
- Softening temperature (1)
- Sol-gel (1)
- Solid-State-Synthesis (1)
- Solvent replacement (1)
- Sorption (1)
- Sorption isotherm (1)
- Spatial analyses (1)
- Spectral irradiation (1)
- Spectral sensitivity (1)
- Stability (1)
- Stainless steels (1)
- Steam-cured concrete (1)
- Steel slag (1)
- Steel-concrete interface (1)
- Stofftransport (1)
- Stone Age (1)
- Stray current (1)
- Streifenlichtprojektion (1)
- Stress-strain relation (1)
- Stress–strain-relation (1)
- Structural build-up (1)
- Structural identification (1)
- Sulfate resistant cement (SRC) (1)
- Sulfur containing polymers (1)
- Superimposed loading (1)
- Superplasticizers (1)
- Supplementary cementitious material (1)
- Supplementary cementitous materials (1)
- Surface (1)
- Surface interactions (1)
- Surfaces, Coatings and Films (1)
- Survey (1)
- Sustainability (1)
- Sustainable binders (1)
- Sustainable cement (1)
- Sustainable construction (1)
- Swelling (1)
- Synergy (1)
- TED-GC/MS (1)
- TGA-FTIR (1)
- TGA-MS (1)
- TIG-welding (1)
- TPU (1)
- TRC (1)
- Tafel Plot (1)
- Tausalz (1)
- Temperature dependency (1)
- Ternary zinc alloys (1)
- Test setup (1)
- Testing procedure (1)
- Thermal transient problem (1)
- Thermally-induced moisture transport (1)
- Thermischer Ausdehnungkoeffizient (1)
- Thermoelectrics (1)
- Thixotropy (1)
- Throwing-stick (1)
- TiMgN (1)
- Titanium nitride (1)
- Tobermorite (1)
- Triplet test (1)
- UV-irradiation (1)
- UV/VIS spectroscopy (1)
- Ultrahigh-performance concrete (UHPC) (1)
- Ultrasonic velocities (1)
- Ultrasound gel (1)
- Umlaufkühler (1)
- Utilization, and storage (CCUS) technology (1)
- Vergleichsuntersuchung (1)
- Vergleichuntersuchung (1)
- Viscosity modifying agents (1)
- Vitrimer (1)
- Vocabulary providers (1)
- Vulcanization (1)
- WAXS (1)
- Waste management (1)
- Water migration (1)
- Wetting (1)
- Whole-chain CCS scenario (1)
- Wire arc additive manufacturing (1)
- Wood (1)
- Working mechanism (1)
- X-ray absorption near-edge structure (1)
- X-ray absorption spectroscopy (1)
- X-ray computed tomography (CT) (1)
- X-ray diffraction (1)
- X-ray diffraction (XRD) (1)
- X-ray photoelectron spectroscopy (1)
- X-ray refraction (1)
- X-ray-CT (1)
- Xpoxy resin (1)
- Yield stress (1)
- Zinkdeckschichten (1)
- Znc (1)
- Zonation (1)
- Zyklische Belastung (1)
- biodegradation (1)
- magnesium (1)
Organisationseinheit der BAM
- 7 Bauwerkssicherheit (183) (entfernen)
Paper des Monats
- ja (2)
Two-dimensional covalent organic frameworks (COFs) based on phosphinine and thiophene building blocks have been synthesized with two different side groups. The materials are denoted as CPSF-MeO and CPSF-EtO where CxxF correspond to the covalent framework, whereas P and S are related to heteroatoms phosphorous and sulfur. MeO and EtO indicate the substituents, i.e. methoxy and ethoxy.
Their morphologies were studied by scanning electron microcopy and X-ray scattering. The absence of crystalline reflexes in the X-ray pattern reveal that both materials are amorphous and can be considered as glasses. Furthermore, N2 adsorption measurements indicate substantial Brunauer–Emmett–Teller (BET) surface area values pointing to the formation of three-dimensional pores by stacking of the aromatic 2D layer. An analysis of the porosity of both COFs showed a mean radius of the pores to be of ca. 4 nm, consistent with their chemical structure. The COFs form nanoparticles with a radius of around 100 nm. The thermal behavior of the COFs was further investigated by fast scanning calorimetry. These investigations showed that both COFs undergo a glass transition. The glass transition temperature of CPSF-EtO is found to be ca. 100 K higher than that for CPSF-MeO. This large difference in the glass transition is discussed to be due to a change in the interaction of the COF sheets induced by the longer ethoxy group. It might be assumed that for CPSF-EtO more individual COF sheets assemble to larger stacks than for CPSF-MeO. This agrees with the much larger surface area value found for CPSF-EtO compared to CPSF-MeO. To corroborate the results obtained be fast scanning calorimetry dielectric measurements were conducted which confirm the occurrence of a dynamic glass transition. The estimated temperature dependence of the relaxation rates of the dielectric relaxation and their absolute values agrees well with the data obtained by fast scanning calorimetry. Considering the fragility approach to the glass transition, it was further found that CPSF-MeO is a fragile glass former whereas CPSF-EtO behaves as a strong glass forming material. This difference in the fragility points also to distinct differences in the interaction between the 2D COF molecules in both materials.
Polymers with intrinsic microporosity (PIMs) are gaining attention as gas separation membranes. Nevertheless, they face limitations due to pronounced physical aging. In this study a covalent organic framework containing λ5-phosphinine moieties, CPSF-EtO were incorporated as a nanofiller (concentration range 0-10 wt%) into a PIM-1 matrix forming dense films with a thickness of ca. 100 μm. The aim of the investigation was to investigate possible enhancements of gas transport properties and mitigating effects on physical aging. The incorporation of the nanofiller occurred on aggregate level with domains up to 100 nm as observed by T-SEM and confirmed by X-ray scattering. Moreover, the X-ray data show that the structure of the microporous network of the PIM-1 matrix is changed by the nanofiller.
As the molecular mobility is fundamental for gas transport as well as for physical aging, the study includes dielectric investigations of pure PIM-1 and PIM-1/CPSF-EtO mixed matrix membranes to establish a correlation between the molecular mobility and the gas transport properties. Using the time-lag method the gas permeability and the permselectivity were determined for N2, O2, CH4 and CO2 for samples with variation in filler content. A significant increase in the permeability of CH4 and CO2 (50 % increase compared to pure PIM-1) was observed for a concentration of 5 wt% of the nanofiller. Furthermore, the most pronounced change in the permselectivity was found for the gas pair CO2/N2 at a filler concentration of 7 wt%.
The output of C&D waste is increasing year by year, among which low-quality recycled brick aggregates (RBAs) have not been well utilized and brought environmental burden. The durability of steam-cured concrete (HCC) is often compromised due to the detrimental effects of this curing regime on the long-term performance and microstructure development of the concrete material. To address this issue, this study investigates the potential of incorporating RBAs to improve the long-term durability of HCC. The results demonstrate that the incorporation of a small amount of RBA (10–20%) not only enhances the 28-d strength of HCC by 2.5–11.3%, but also improves its impermeability by mitigating heat damage effects. The combined application of fine and coarse RBA was found to effectively balance the negative effects of coarse RBA on the performance of HCC. Furthermore, the utilization of RBA in HCC was shown to have economic and environmental benefits. The results of this study demonstrate a simple and effective approach to improve the long-term durability of HCC while promoting the high-value utilization of solid waste.
Esta pesquisa avaliou o fenômeno de autocicatrização nas propriedades mecânicas e absorção capilar de concretos estruturais. Foram avaliados dois aditivos cristalizantes em pó, dosados de acordo com o teor recomendado pelos fabricantes. Aditivos cristalizantes aumentam a densidade do gel C-S-H e formam cristais insolúveis, bloqueando fissuras. Três traços de concreto foram produzidos: referência, aditivo-X com 0,8% e aditivo-Y com 2,0% em relação a massa do cimento. Aplicou-se 75% da carga de ruptura aos 3- e 14-dias para gerar microfissuras e comparar com a referência. Posteriormente, a autocicatrização foi avaliada aos 28- e 76-dias. A propriedade de resistência à compressão axial foi determinada aos 28-dias, revelando que os aditivos cristalizantes contribuíram para um aumento médio de 12% desta propriedade. A idade do carregamento dos concretos não apresentou um impacto significativo na resistência à compressão axial, mas apontou resultados significativos entre os tipos de aditivos estudados, conforme ANOVA. As propriedades de absorção de água por capilaridade foram avaliadas aos 28- e 76-dias, indicando uma redução de absorção de água média de 42% devido ao uso dos aditivos cristalizantes. Em conclusão, a incorporação dos aditivos cristalizantes contribuiu de maneira positiva para a autocicatrização dos concretos estudados, indicando uma recuperação parcial das microfissuras.
Despite the advances in hardware and software techniques, standard numerical methods fail in providing real-time simulations, especially for complex processes such as additive manufacturing applications. A real-time simulation enables process control through the combination of process monitoring and automated feedback, which increases the flexibility and quality of a process. Typically, before producing a whole additive manufacturing structure, a simplified experiment in the form of a beadon-plate experiment is performed to get a first insight into the process and to set parameters suitably. In this work, a reduced order model for the transient thermal problem of the bead-on-plate weld simulation is developed, allowing an efficient model calibration and control of the process. The proposed approach applies the proper generalized decomposition (PGD) method, a popular model order reduction technique, to decrease the computational effort of each model evaluation required multiple times in parameter estimation, control, and optimization. The welding torch is modeled by a moving heat source, which leads to difficulties separating space and time, a key ingredient in PGD simulations. A novel approach for separating space and time is applied and extended to 3D problems allowing the derivation of an efficient separated representation of the temperature.
The results are verified against a standard finite element model showing excellent agreement. The reduced order model is also leveraged in a Bayesian model parameter estimation setup, speeding up calibrations and ultimately leading to an optimized real-time simulation approach for welding experiment using synthetic as well as real measurement data.
Thermal transient problems, essential for modeling applications like welding and additive metal manufacturing, are characterized by a dynamic evolution of temperature. Accurately simulating these phenomena is often computationally expensive, thus limiting their applications, for example for model parameter estimation or online process control. Model order reduction, a solution to preserve the accuracy while reducing the computation time, is explored. This article addresses challenges in developing reduced order models using the proper generalized decomposition (PGD) for transient thermal problems with a specific treatment of the moving heat source within the reduced model. Factors affecting accuracy, convergence, and computational cost, such as discretization methods (finite element and finite difference), a dimensionless formulation, the size of the heat source, and the inclusion of material parameters as additional PGD variables are examined across progressively complex examples. The results demonstrate the influence of these factors on the PGD model’s performance and emphasize the importance of their consideration when implementing such models. For thermal example, it is demonstrated that a PGD model with a finite difference discretization in time, a dimensionless representation, a mapping for a moving heat source, and a spatial domain non-separation yields the best approximation to the full order model.
Oxidative aging induces significant stiffening of asphalt binders that leads to a pronounced reduction in the overall durability of asphalt pavements. The strategic implementation of antioxidant additives provides a potential solution to alleviate this issue. This work presents results from the second phase of the global consortium for antioxidants research aimed at investigating the effectiveness of potential antioxidants in increasing the durability of asphalt binders. Sixteen laboratories around the world participated in this effort and a total of 28 binders from diverse geographical regions were tested. Two promising antioxidants, namely zinc diethyldithiocarbamate (ZDC) and kraft lignin were evaluated in this phase and blended with the binders at specific proportions. Subsequently, a comprehensive investigation was conducted to assess rheological characteristics and chemical properties of the various blends, utilising Dynamic Shear Rheometer (DSR) measurements and Fourier Transform Infrared (FTIR) Spectroscopy. The findings indicate that additives such as ZDC hold considerable promise as an effective antioxidant, particularly when considering a wide diversity of binders. In general, its incorporation does not compromise the rutting performance of the binders and significantly improves fatigue performance. Therefore, research efforts should be focused on exploring additional facets to assess its practical applicability in field.
Durch Auslagerungs- und elektrochemische Tests im Labor kann das Korrosionsverhalten verschiedener metallener Werkstoffe beurteilt werden. Aus den Versuchsergebnissen, die in verschiedenen synthetischen Geothermalwässern im Labor erzielt wurden, lassen sich die folgenden Schlussfolgerungen ziehen:
• Die Anfälligkeit für Spaltkorrosion wurde als wichtigster Aspekt für die Werkstoffqualifizierung ermittelt.
• Der niedriglegierte Stahl 25CrMo4 zeigte bei niedrigem Salzgehalt in MB-Geothermalwasser eine gleichmäßige Korrosion unterhalb der akzeptierten Schwelle von 0,3 mm/Jahr. Daher kann er als geeignet für geothermische Bedingungen mit niedrigem Salzgehalt angesehen werden, wie sie für MB getestet wurden. Es besteht keine Notwendigkeit, auf höherlegierte (teurere) Werkstoffe auszuweichen. Ein niedrigerer pH-Wert (wie bei LHD) führt zu Korrosionsraten oberhalb der akzeptablen Grenzwerte, so dass die niedriglegierten Werkstoffe nicht für Flüssigkeiten mit niedrigem pH-Wert geeignet sind.
• Stark salzhaltige Geothermalwässer erfordern höherlegierte Werkstoffe, da die Korrosionsrate von niedriglegiertem Stahl zu hoch ist.
• Der Duplexstahl X2CrNiMo22-5-3 und der Superduplexstahl X2CrNiMoCuWN25-7-4 wurden aufgrund ihrer kritischen Anfälligkeit für örtliche Korrosion in Form von Loch- und Spaltkorrosion unter Betriebsbedingungen nicht als geeignet für geothermische Anwendungen in Geothermalwässern mit einer mit NDB und ORG vergleichbaren Zusammensetzung angesehen.
• Der superaustenitische Stahl X1CrNiMoCu32-28-7 eignet sich für ORG und salzarme Wässer. In NDB-Geothermalwasser wurde er bei 100 °C als geeignet angesehen. Jedoch schränkt seine Anfälligkeit für Spaltkorrosion seine Anwendbarkeit ein. Neben seiner guten Korrosionsbeständigkeit ist sein Repassivierungsverhalten für seine begrenzte Anwendbarkeit in Geothermalwässern mit niedrigem pH-Wert verantwortlich.
• Die Nickelbasislegierung NiCr23Mo16Al wurde als geeignet erachtet und stellt eine sichere Option für den Einsatz in geothermischen Anlagen dar, selbst wenn mit stark salzhaltigem Geothermalwasser gearbeitet wird.
Durch Auslagerungs- und elektrochemische Tests im Labor kann das Korrosionsverhalten verschiedener metallener Werkstoffe beurteilt werden. Aus den Versuchsergebnissen, die in verschiedenen synthetischen Geothermalwässern im Labor erzielt wurden, lassen sich die folgenden Schlussfolgerungen ziehen:
• Die Anfälligkeit für Spaltkorrosion wurde als wichtigster Aspekt für die Werkstoffqualifizierung ermittelt.
• Der niedriglegierte Stahl 25CrMo4 zeigte bei niedrigem Salzgehalt in MB-Geothermalwasser eine gleichmäßige Korrosion unterhalb der akzeptierten Schwelle von 0,3 mm/Jahr. Daher kann er als geeignet für geothermische Bedingungen mit niedrigem Salzgehalt angesehen werden, wie sie für MB getestet wurden. Es besteht keine Notwendigkeit, auf höherlegierte (teurere) Werkstoffe auszuweichen. Ein niedrigerer pH-Wert (wie bei LHD) führt zu Korrosionsraten oberhalb der akzeptablen Grenzwerte, so dass die niedriglegierten Werkstoffe nicht für Flüssigkeiten mit niedrigem pH-Wert geeignet sind.
• Stark salzhaltige Geothermalwässer erfordern höherlegierte Werkstoffe, da die Korrosionsrate von niedriglegiertem Stahl zu hoch ist.
• Der Duplexstahl X2CrNiMo22-5-3 und der Superduplexstahl X2CrNiMoCuWN25-7-4 wurden aufgrund ihrer kritischen Anfälligkeit für örtliche Korrosion in Form von Loch- und Spaltkorrosion unter Betriebsbedingungen nicht als geeignet für geothermische Anwendungen in Geothermalwässern mit einer mit NDB und ORG vergleichbaren Zusammensetzung angesehen.
• Der superaustenitische Stahl X1CrNiMoCu32-28-7 eignet sich für ORG und salzarme Wässer. In NDB-Geothermalwasser wurde er bei 100 °C als geeignet angesehen. Jedoch schränkt seine Anfälligkeit für Spaltkorrosion seine Anwendbarkeit ein. Neben seiner guten Korrosionsbeständigkeit ist sein Repassivierungsverhalten für seine begrenzte Anwendbarkeit in Geothermalwässern mit niedrigem pH-Wert verantwortlich.
• Die Nickelbasislegierung NiCr23Mo16Al wurde als geeignet erachtet und stellt eine sichere Option für den Einsatz in geothermischen Anlagen dar, selbst wenn mit stark salzhaltigem Geothermalwasser gearbeitet wird.
The corrosion behavior of galvanized steels and zinc components under atmospheric exposure depends mostly on the corrosion product‐based cover layer formation under the prevailing conditions. The use of agar‐based gel electrolytes makes it possible to use electrochemical methods to obtain a characteristic value from these cover layers that describe their current and future protective capacity. It is shown here that different states of galvanized steel can be distinguished very well under laboratory conditions and that this method is also suitable for use under practical conditions. Based on the characteristic values and assuming future time of wetness, it is very easy to draw up a forecast for the future corrosion rate, which provides plausible values.