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Corrosion in reinforced concrete structures is among the major degradation mechanisms. The quantification and description of the spatial distribution of the corrosion condition within a structure on the basis of condition assessments are important. This study considered half-cell potential mapping data as a widely used technique to detect corrosion in reinforced concrete structures. A four-step workflow was proposed to analyse half-cell potential data with geostatistical techniques, first consisting of trend identification and possible trend removal. The obtained residuals were then subjected to a quantile-quantile transformation. Subsequently, experimental variograms were calculated and fitted with variogram models to estimate the correlation lengths. A case study with data from a road tunnel confirms the applicability of the workflow. It was assumed that the identified trend is primarily a result of the heterogeneity of the exposure conditions within the structure that ranges several metres. The residuals are interpreted as the result of the heterogeneities of material resistances that give rise to spatial variability in corrosion probability on a shorter distance range. The proposed analysis may be utilised for service life modelling (e.g. based on random fields), planning maintenance works, or optimising the grid size for half-cell potential measurements. [ABSTRACT FROM AUTHOR]

This article discusses the use of digital methods, such as building information modeling (BIM) and structural health monitoring (SHM), in the maintenance management of a highway bridge in Germany. The goal is to combine these tools to create a comprehensive digital platform that organizes knowledge, incorporates real-time measurements, and provides feedback to the structural model and designer. The bridge is described in detail, including its dimensions and construction history. The monitoring system installed on the bridge measures various variables, including strain, vibration, inclination, displacement, temperature, and traffic loads. The article emphasizes the importance of a holistic understanding of the bridge's behavior and the need for collaboration between industry, academia, and federal institutions to address the challenges of digital bridge management. The authors express their willingness to share data and collaborate with others in the field. [Extracted from the article]

ABSTRACT This study investigates the influence of cathodic polarization on the chloride threshold (CT) for carbon steel in alkaline solutions, analogous to reinforcing steel embedded in concrete, with a focus on the electrochemical steel potential as a critical factor for corrosion initiation. The research, incorporating a literature review and potentiostatic tests, reveals that CT shows potential independence at potentials more anodic than −200 mVSCE and increases for potentials more cathodic than −200 mVSCE. The observed increase in CT under cathodic polarization is attributed to alterations in the passive layer composition, supporting the existence of distinct potential regions that govern the onset of corrosion. [ABSTRACT FROM AUTHOR]

Autogenous self-healing of water retaining concrete structures is included in Eurocode 1992-3 as a possibility to heal cracks up to a width of 200 μm without additional repair. In this self-healing scenario water flow through a crack should result in a progressive closure of the fracture, mainly due to CaCO3 precipitation, when certain hydraulic gradients are met, the pH of the water is > 5.5 and the concentration of CO2 in the water remains < 40 mg*L-1. The material composition is not further restricted by the regulation. However, despite standardization, the healing effect seems to be random in practice, which requires further research, while experiments aimed at quantifying autogenous self-healing are expensive and time-consuming. Thermodynamic models could support in estimating the effect of different environments such as groundwater or seawater exposure on autogenous self-healing. Moreover, adjusting the water chemistry according to the conditions of different construction sites and changing the material design could easily be considered. In this study thermodynamic models of a hydrated CEM I 52.5 R paste that is exposed to either simulated groundwater or seawater are discussed concerning the influence on autogenous self-healing and compared to experimental and literature data.

Reinforced concrete (RC) is the most used construction material for infrastructure due to its strength and durability. However, under chloride exposure, often the RC structures do not achieve their designed service life. Therefore, premature repairs or even replacement of components is required, hence increasing the environmental impacts and economic costs over the entire service life. This study evaluates the sustainability of low-clinker cements as a corrosion prevention measure in reinforced concrete under several chloride exposures conditions. Through a life cycle assessment (LCA), the environmental impacts of a RC generic element are evaluated, considering three alternatives for low-clinker cement and ordinary Portland cement as reference. The materials production and use service are considered in the LCA. The service phase includes the repair activities necessary to keep a defined level of serviceability given the steel corrosion due to chloride ingress. The number of repairs is determined on a probabilistic durability assessment. The results showed that the durability of the reinforced element plays a major role in the overall environmental impacts. Furthermore, low-clinker binders have a positive environmental impact in the sustainability of reinforced concrete structures.

Structural health monitoring is the process of implementing a continuous damage detection strategy to optimize the inspection and maintenance schedules of bridges, and extend their lifespans. One of the main challenges of automated damage detection is the lack of data on damaged states, which makes it difficult to validate new approaches in the research and development stage. To alleviate this problem, a monitoring campaign on a two‐span test bridge with defined defects is conducted and documented in this article. The bridge is a steel‐concrete composite structure with a length of 30 m, with two primary steel girders and a segmented concrete deck. The recorded data capture the long‐term ambient data from 18 test days and changing environmental conditions, as well as the short‐term ambient data and dynamic load tests from four damage scenarios with well‐defined damage extents. A mobile measurement system with numerous sensors is used for data acquisition. A shaker is placed on the bridge to excite white noise. The main goal of this article is to document the experimental procedure and perform preliminary plausibility checks on the measured data. First results demonstrate that system response data and environmental conditions are recorded reliably and that environmental effects significantly affect the long‐term measurements. Therefore, a suitable data set is provided as open‐source data for future studies on data normalization and automated damage detection. [ABSTRACT FROM AUTHOR]

Fusion-bonded-epoxy (FBE)-coated steel rebars have been used in many concrete structures in anticipation of better corrosion resistance. However, due to premature corrosion observed, FBE-coated rebars are banned in many parts of the world. On the other hand, such rebars with damaged coating are still used widely in some other parts of the world. This paper discusses the thickness, continuity, flexibility, and chemical composition of coating. Also, the performance indicators such as electrical resistance, UV-resistance, moisture resistance, and chloride diffusion coefficient of coating, and the chloride threshold of FBE-coated rebars are discussed. Laboratory tests adopted techniques (EIS, LA-ICP-MS, and EDX) on samples of coating peeled-off from coated rebars and specimens of coated steel rebars embedded in cement mortar, indicate that more comprehensive and stringent specifications are required to promote the use of quality epoxy materials, FBE-coated steel rebars, and construction practices are recommended. [ABSTRACT FROM AUTHOR]

Cracks in concrete structures can serve as pathways for aggressive chemical substances that can lead to a progressive deterioration of the cement stone as well as of the reinforcement, affecting the load capacity, service life and useability of concrete structures. However, concrete and reinforced concrete exhibit an intrinsic ability to heal cracks, defined as autogenous self‐healing. This effect includes the precipitation of calcium carbonate in the presence of water and CO2 and is accompanied by continued hydration, swelling, and mechanical blocking of the crack pathway. Experiments led to the inclusion of crack sealing by autogenous self‐healing in Eurocode 1992–3 for water retaining concrete structures. However, despite code restrictions, autogenous self‐healing of concrete shows limited effectiveness in practice. This indicates the need for further research to provide engineers with reliable design rules. Therefore, this study aims for giving a broad literature review on the state‐of‐the‐art knowledge on autogenous self‐healing, the boundary conditions, consensus, and controversy of processes and factors influencing the efficiency of autogenous self‐healing. Regarding the transferability of laboratory results to real concrete constructions, materials, crack initiation techniques, experimental concepts, and methods for assessing the effectiveness of autogenous self‐healing are discussed and recommendations for future experiments are set. [ABSTRACT FROM AUTHOR]

Reinforced concrete structures are the backbone of the transportation infrastructure. Their structural safety and functional performance are critical to sustaining a globalized economy. Corrosion of steel reinforcement is typically triggered by chloride contamination and carbonation, becoming a primary factor in reinforced concrete deterioration. This paper presents a durability assessment of a tunnel structure located in a tropical marine environment. The condition assessment included visual examination, crack survey, cover depth measurements, half‐cell potential mapping, and concrete coring. The chloride profiles showed that the tunnel walls are subjected to chloride attack from both surfaces, an unusual finding in the literature. A stochastic approach is implemented to estimate the probability of corrosion initiation for chlorides and carbonation, including an innovative model for two‐sided chloride diffusion. The results indicate that two‐sided chloride exposure significantly reduces the corrosion initiation time. [ABSTRACT FROM AUTHOR]

The critical chloride content Ccrit is an indicator of the corrosion resistance of reinforcing steels in concrete. In this article, several experimental methods for determining the critical chloride content Ccrit of mild and alloyed (12% Cr) steel in cementitious materials are compared. The methods used include accelerated polarization tests and tests employing more natural (unpolarized) conditions in which chloride ingress occurs by diffusion and capillary uptake. The advantages and disadvantages of the methods are discussed, in particular, against the objective of reaching a compromise between applicability to practice and feasibility in laboratory testing. [ABSTRACT FROM AUTHOR]