A5080766487- Concrete Corrosion and Durability
- Concrete and Cement Materials Research
- Corrosion Behavior and Inhibition
- Magnesium Oxide Properties and Applications
- Concrete Properties and Behavior
- Iron oxide chemistry and applications
- Innovative concrete reinforcement materials
- Mine drainage and remediation techniques
- Metal Extraction and Bioleaching
- Radioactive element chemistry and processing
- Arsenic contamination and mitigation
- Anodic Oxide Films and Nanostructures
- Material Properties and Applications
- Smart Materials for Construction
- Hydrogen embrittlement and corrosion behaviors in metals
- Electrochemical Analysis and Applications
- Metallurgical Processes and Thermodynamics
- Masonry and Concrete Structural Analysis
- Water Treatment and Disinfection
- Endodontics and Root Canal Treatments
- Dental Erosion and Treatment
- Dental materials and restorations
- Lanthanide and Transition Metal Complexes
- Iron Metabolism and Disorders
- Fire effects on concrete materials
ETH Zurich
2021-2025
Institute for Biomedical Engineering
2023-2024
Federal Institute For Materials Research and Testing
2019-2021
University of Sheffield
2015-2021
Philips (Netherlands)
2015
Bhabha Atomic Research Centre
1987
The passivation and chloride-induced depassivation of steel rebars immersed in varying alkaline environments (0.80 M, 1.12 M 1.36 NaOH solutions), simulating the pore solutions low-Ca alkali-activated concretes, were investigated using a range electrochemical techniques. passive film on was complex chemical makeup, composed Fe–hydroxides, oxy-hydroxides oxides. An increased degree observed when exposed to with higher hydroxide concentrations. critical chloride level ([Cl−]/[OH−] ratio)...
Aqueous iron hydrolysis products and chloride complexes influence steel corrosion kinetics dictate the amount type of formed. Here, we compile a thermodynamic database devoted to aqueous species solid oxides as well complexes, aiming describe their speciation solubility within prevailing chemical environment interest for cementitious systems. We compare calculations empirical data on elemental composition pore solutions from It is found that dissolved concentrations in cement can differ...
The transformation of 2-line ferrihydrite to goethite from supersaturated solutions at alkaline pH ≥ 13.0 was studied using a combination benchtop and advanced synchrotron techniques such as X-ray diffraction, thermogravimetric analysis, absorption spectroscopy. In comparison the rates acidic mildly environments, half-life, t1/2, reduces several months = 2.0, approximately 15 days 10.0, just under 5 h 14.0. calculated-first order rate constants transformation, k, increase exponentially with...
The development of alkali-activated materials (AAMs) as an alternative to Portland cement (PC) has seen significant progress in the past decades. However, there still remains uncertainty regarding their long term performance when used steel-reinforced structures. durability AAMs such applications depends strongly on corrosion behaviour embedded steel reinforcement, and experimental data literature are limited some cases inconsistent. This letter elucidates role chemistry mechanisms governing...
Abstract The pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on surface film formed steel reinforcement poorly understood. This study investigates critical role HS − defining mild passivation chemistry. contains Fe(OH) 2 Fe–S complexes, chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior dependent duration exposure electrolyte, nature sulfidic layer.
Whilst the oxidation of Fe(II) in aerobic conditions has been studied thoroughly, an in-depth knowhow on fate or stability solutions with near-neutral pH under anaerobic is still lacking. Here, we experimentally investigated kinetics ranging between ∼5 and 9, (when were equilibrium atmospheric oxygen) dissolved oxygen concentration was ∼10−10 mol/L), by colorimetric means. Experimental results thermodynamic considerations presented here, show that first-order w.r.t. [Fe(II)], proceeds set...
Numerous aqueous systems host elements in multiple redox states, with wide ranging implications such as their influence on the formation/dissolution of minerals, water toxicity, and nutrient cycling. To uncover governing mechanisms complex chemical interactions systems, reactive-transport models have increasingly gained importance. However, predictive capabilities remain limited because existing approaches struggle to accurately account for full complexities reactions. Here, we develop a...
Abstract Macroscopic voids at the steel–concrete interface and their degree of saturation with an aqueous electrolyte are known to play important role in corrosion steel reinforced concrete. Irrespective exposure conditions testing parameters, majority studies products have been reported consistently precipitate a unique pattern within these macroscopic voids, preferentially along void walls growing inward. The underlying mechanisms governing product precipitation effects on long-term...
For more than a century, the corrosion of steel in concrete has prevailed as complex and yet poorly understood phenomenon, with many durability design approaches relying on phenomenological or semi-empirical service life models. The increasing societal demand to maintain aging infrastructure, development new cementitious binders push towards an environmentally benign circular economy exacerbate need for comprehensive scientific understanding underlying physicochemical processes, particularly...
Abstract Alkali‐activated materials (AAMs) are binders that can complement and partially substitute the current use of conventional cement. However, present knowledge about how AAMs protect steel reinforcement in concrete elements is incomplete, uncertainties exist regarding application electrochemical methods to investigate this issue. The review by EFC WP11‐Task Force ‘Corrosion alkali‐activated materials’ demonstrates important differences between Portland cement, different classes AAMs,...
Accurate model predictions of corrosion-driven damage in reinforced concrete structures necessitate a comprehensive understanding the rate corrosion product formation. Here, we investigate influence dissolved Si characteristic cementitious systems on transformation at alkaline pH. Compared to aged absence Si, small amounts decrease formation thermodynamically stable goethite by factor 10. The estimated first order constant k decreases exponentially as function concentration and follows...
The formation of energetically favorable and metastable mineral phases within the Fe-H
Corrosion of steel reinforcement in concrete is a common degradation mechanism occurring infrastructures worldwide. Even though extensive research has been conducted over the last decades to accurately predict influence corrosion on durability, comprehensive understanding several micro-scale processes simultaneously involved still lacking. The application X-ray Computed Tomography (X-ray CT) can contribute elucidate these processes, since this technique allows observing internal status...
We introduce an experimental setup to chemically image corrosion processes at metal-electrolyte interfaces under stagnant, confined conditions-relevant in a wide range of situations. The is based on glass capillary, which precipitation products the interfacial aqueous phase can be monitored over time with optical microscopy, and structurally characterized microscopic synchrotron-based techniques (X-ray fluorescence, X-ray diffraction, absorption spectroscopy). Moreover, quantification...
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