Documents published in Scipedia

• Assessment of the Impressed Current Cathodic Protection System after 4 Years Operation: Evolution Over Temperature and Time of the Applied Current and Tension on Anodic Zones of the Saint-Cloud Viaduct (France)

  J. Ducasse-Lapeyrusse, V. Bouteiller, O. Lesieutre, E. Marie-Victoire, M. Bouichou, G. Damien, V. Martinet, C. Annede-Villeau

  DBMC 2023.

  
  

  Abstract

  This paper presents the feedback of the Impressed Current Cathodic Protection (ICCP) system implemented on a road bridge, the Viaduct of Saint-Cloud, constructed in the 1970s in France. After a test trial in 2012, the full-scale ICCP system was energized in 2018. It consisted of 44359 discrete titanium anodes implemented on the lateral segment webs on both sides of the Viaduct, distributed in 212 anodic zones on one side and 153 anodic zones on the other side. The four years monitoring data include the variations of the applied current and tension on anodic zones, their polarization, etc. This paper focus on the global resistance of the circuit for the different anodic zones. The circuit resistance shows first the influence of the temperature. The differences between anodic zones and their evolution over time also bring more information about the environment of the anodes and the reinforcements. The analysis of the response of the circuit reveals the heterogeneity of an actual and large-scale ICCP system and provides important feedback to an appropriate ICCP design for durable cathodic protection.

  Abstract
  This paper presents the feedback of the Impressed Current Cathodic Protection (ICCP) system implemented on a road bridge, the Viaduct of Saint-Cloud, constructed in the 1970s [...]

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• Analytical and Experimental Service Life Assessment of Ningbo-Zhoushan Port Main Channel Sea Link Project

  L. Li, K. Li, R. Torrent

  DBMC 2023.

  
  

  Abstract

  The Ningbo-Zhoushan Port Main Channel (NZPMC) sea link is one of the most important projects undertaken by the People's Republic of China. The main factors that determine the service life of these marine structures, exposed to chloride-induced corrosion, are the "penetrability" and thickness of the concrete cover that protects the steel reinforcement. In an initial design phase, these factors are defined by modeling the penetration of chlorides with analytical tools (based on the Duracrete approach). In the construction phase, data are collected from the in-site laboratory for concrete chloride diffusivity, and from non-destructive tests for the concrete cover thickness and air permeability for the prefabricated bridge piers. On the basis of these data, two model-based approaches are used to predict the service life of the bridge. The first model is an analytical one based on the solution of Fick’s 2nd diffusion law, for chloride ingress into concrete using the corrosion initiation as durability limit state.The second model uses the “Exp-Ref” model, using the concrete cover thickness and air permeability as input parameters and calibrated by the EuroCode specifications on structural concretes in marine environments. Both approaches use Monte-Carlo simulations and consider the statistical properties of the input parameters. A comparison of the analytical and experimental predictions is made, showing compatibility with 100 years of service life. The convenience of verifying the analytical predictions with those obtained from site experimental data is discussed.

  Abstract
  The Ningbo-Zhoushan Port Main Channel (NZPMC) sea link is one of the most important projects undertaken by the People's Republic of China. The main factors that determine [...]

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• An In-situ Method for Assessing the Kinetics of Acid Attack on Iron-richAlkali-activated Materials

  Z. Yu, R. Oliveira-Silva, E. De Oliveira, N. Wen, Y. Pontikes, D. Sakellariou

  DBMC 2023.

  
  

  Abstract

  In iron-rich alkali-activated materials (AAMs), iron is present in both the ferrous and ferric states. Fe3+ is considered to be present in a silicate network and the dissolution of Fe3+ under acid attack can be taken as an indication of the deterioration of the AAMs framework. Conventional methods for evaluating the acid resistance of AAMs are based on the durability standards for OPC concrete with indicators such as mass change and dimensional change, or by measuring the corroded depth. All of these methods are measured based on solid samples and many samples have to be prepared to obtain different points in a time profile. Here we propose nuclear magnetic resonance (NMR) relaxometry measurements as an in-situ method for the direct determination of dissolution kinetics of Fe3+ ions in an acid solution with high temporal resolution. The leaching kinetics of iron-rich AAMs in (sulfuric) acid can be described by the Real Physical Picture (RPP) kinetic model, which was originally used to describe the gas-solid interaction. The fitting results show that the leaching process is controlled by chemical reactions at the beginning and by diffusion over time.

  Abstract
  In iron-rich alkali-activated materials (AAMs), iron is present in both the ferrous and ferric states. Fe3+ is considered to be present in a silicate network and the dissolution [...]

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• Experimental Study of the Development of Stresses in Prestressing Strandsunder Different Environments

  D. Xu, C. Chen, Y. Zhao

  DBMC 2023.

  
  

  Abstract

  This paper presents findings from an experimental study on the effects of different environmental factors on post-tensioned prestressed concrete beams. The study included four different environments: outdoor shielded, drying-wetting cycles with tap water, drying-wetting cycles with NaCl solution, and drying-wetting cycles with NaCl solution and energized longitudinal rebars. A vibratingstring anchor cable dynamometer was used to measure the stress variation in prestressing strands. The results indicate that ambient temperature affects the trend of stresses in the prestressing strands. The increasing humidity caused by drying-wetting cycles and increasing salinity caused by NaCl solution led to the expansion of the concrete and increased stresses in the prestressing strands. Additionally, the corrosion of longitudinal rebars caused by the impressed-current accelerated corrosion method results in concrete damage and cracking, and continuously decreases the stresses in the prestressing strands. The study is ongoing, and further observations and reports will be made to evaluate the effects of different environmental factors on stresses in prestressing strands of post-tensioned beams.

  Abstract
  This paper presents findings from an experimental study on the effects of different environmental factors on post-tensioned prestressed concrete beams. The study included [...]

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• Exploring Moisture Performance of Two Distinctive Solid Bricks underCurrent and Future Climate in London

  B. Xu, S. Zhang, T. Cambray, V. Marincioni

  DBMC 2023.

  
  

  Abstract

  The increasing concerns surrounding climate change have raised apprehension about the heightened frequency and intensity of extreme weather events, globally as well as in the UK. Historic solid brick buildings, due to their construction materials and prolonged exposure to changing climate conditions, are vulnerable to the impacts of climate change, resulting in increased moisture risks that undermine their durability. Understanding the moisture behaviour of solid bricks facing climate change is therefore significant. This study aims to investigate the moisture performance, with a specific focus on moisture content, of two distinct types of bricks: handmade bricks from the 19th century and more recent – early 20th century - bricks, under current and future climate scenarios in London. The results reveal that the more recent bricks can have greater susceptibility to climate changes, providing valuable insights for the implementation of effective moisture control strategies and informed decision-making in the retrofitting of solid brick buildings in the UK.

  Abstract
  The increasing concerns surrounding climate change have raised apprehension about the heightened frequency and intensity of extreme weather events, globally as well as in [...]

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• Freeze-thaw Damage Mechanism and Cracking Behaviour of PerforatedPlateau Concrete Structure

  J. Mao, K. Fang, L. Mi, H. Jia

  DBMC 2023.

  
  

  Abstract

  The harsh environment and poor quality of building materials used in plateau concrete projects adversely affect the ability of such structures to withstand the damaging impact of freeze-thaw. A fast-freezing test with a single variable control was carried out and the process of microstructural changes in the plateau concrete was traced. The results also showed that the plateau curing environment led to an increase in width and porosity of the interface transition zone (ITZ), and that clay content in building materials significantly impacted the microstructure of paste. The frost resistance of plateau concrete was found to be far lower than that of plain concrete. Perforated concrete structures are common in engineering, and concrete members can easily experience frost cracking in cold regions. This study conducts frost heave tests on perforated concrete, aiming at the problem of the frost heave cracking risk of perforated concrete structures in cold regions. The cracking characteristics of concrete with holes under freeze-thaw cycles are mastered by performing rapid freeze-thaw tests on concrete with holes and observing the cracked section. Finally, hydrophobic filling materials were adopted to alleviate the frost heave stress on concrete.

  Abstract
  The harsh environment and poor quality of building materials used in plateau concrete projects adversely affect the ability of such structures to withstand the damaging impact [...]

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• Hygrothermal Performance of CLT Subjected to Rain Loads duringConstruction in Belgium

  K. Habtie, B. Vanderschelden, X. Jiang, L. De Ligne, J. Van Den Bulcke, N. Van Den Bossche

  DBMC 2023.

  
  

  Abstract

  As the use of CLT is increasing, it is important to understand how to deal with moisture during construction. Throughout the construction phase it is often not feasible to shield every component and detail from direct rain impingement. This paper investigates what happens to CLT, and spruce wood in general, when it is exposed to rain events, and how fast it dries out afterwards. Subsequently, the implications of incorporating a wetted component into a finished wall system is also investigated. The moisture behaviour of both plain spruce and CLT samples that are exposed outdoors is investigated using the continuous moisture measurement (CMM) setup at the UGent Woodlab in combination with hygrothermal simulations in Delphin 6. Pieces of solid wood and CLT are mounted on load cells that record the weight every 5 minutes, to study the wetting and drying behavior. Hygrothermal simulations are done in Delphin 6 using a climate file that is made from the recorded weather data. This way, the CMM experiments can be recreated in simulations. The goal here is to understand what is happening in the simulations and to look at what influence different parameters have on the moisture content of the samples. Risks of mould and wood decay are investigated, and recommendations are made concerning practical moisture management and risk mititagion for these types of constructions.

  Abstract
  As the use of CLT is increasing, it is important to understand how to deal with moisture during construction. Throughout the construction phase it is often not feasible to [...]

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• Numerical Simulation on the Pouring Process of Self-compacting Concretein CRTS III Slab Track

  H. Zhang, Y. Zhang, K. Wu

  DBMC 2023.

  
  

  Abstract

  In this study, a fluid-solid coupling model describing the pouring process of self-compacting concrete (SCC) in CRTS III ballastless slab track in straight section was established based on a coupled Eulerian-Lagrangian method, which realized the simulation of the whole pouring process of SCC. The influence law and mechanism of different construction parameters on the pouring process of SCC were studied theoretically. The effects of height and number of funnels on some key indices including the filling rate of SCC, the vertical and lateral displacements of slab track and the forces of withhold were mainly analyzed. The study was aimed at providing theoretical guidance for the intelligent pouring of SCC and the development of intelligent pouring equipment. Results indicated that the higher funnel and double-hole pouring both reduced the pouring time and improved the construction efficiency, and the latter one demonstrated a significant effect. The maximum vertical displacement of track slab was appeared in the middle of slab edge during single-hole pouring but was found in the vicinity of observation hole during double-hole pouring. The maximum lateral displacement of track slab was appeared near the withhold during the pouring process. A higher funnel led to greater pressure of SCC to track slab, which brought about larger vertical and lateral displacements of slab track and higher forces of withhold. Compared to single-hole pouring, the final floating dis-placement and lateral displacement of slab track and the force of withhold were greater during double-hole pouring

  Abstract
  In this study, a fluid-solid coupling model describing the pouring process of self-compacting concrete (SCC) in CRTS III ballastless slab track in straight section was established [...]

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• Modeling the Sulfate-induced Damage of Concrete

  P. Dangla, Y. Gu, Y. Omikrine-Metalssi, R. Martin

  DBMC 2023.

  
  

  Abstract

  The degradation of concrete due to sulfate attack from internal or external sources is a serious problem. The cause of this degradation is the formation and growth of ettringite, which results from the reaction of cement hydrates with sulfate ions in the pore network. This crystal growth leads to a pore pressure that can exceed the concrete’s strength. This paper presents a modeling of concrete’s sulfate-induced stress-strain behavior based on damage poromechanics and two kinetic laws for ettringite growth. Free expansion of cement paste samples exposed to sulfate solutions were measured, and mercury porosimetry tests were conducted at different expansion stages. The pore size distribution was analyzed to locate the dissolution of hydrates and precipitation of ettringite at the pore scale. Results support the theory that ettringite first precipitates in larger capillary pores and spreads to smaller ones. A heat-based dissolution test was performed at different expansion stages, revealing ettringite formed in the pore size range of 4-30 nm. The model was implemented in a finite volume code and applied to four experimental cases from the literature: ESA and DEF in confined and free conditions. The kinetic coefficients were calibrated to fit the observed strains in some experiments and used to blindly test the model in others. Diffusion was neglected due to the small sample size. All simulations showed that the calibrated kinetic parameters had the same order of magnitude, supporting the right physics involved

  Abstract
  The degradation of concrete due to sulfate attack from internal or external sources is a serious problem. The cause of this degradation is the formation and growth of ettringite, [...]

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• MARS – A Multiphysics Framework for the Analysis of Cast and PrintedConcrete

  A. Cibelli, R. Wan-Wendner, J. Vorel, D. Pelessone

  DBMC 2023.

  
  

  Abstract

  Predicting the time-dependent responses of concrete and concrete structures remains a challenging task in the construction sector. While experimental investigation serves as an essential cornerstone for concrete research, by itself it only offers limited insights into the complex time-dependent behaviour of concrete. The complexity is due to the multiple coupled hygro-thermo-chemo-mechanical processes. In the last two decades MARS, a special purpose computational software developed by ES3, has shown the capability of turning such insights accessible. This paper aims to provide a state-of-theart of the MARS capabilities in concrete modelling, enriched with a discussion of some meaningful examples. The multiphysics framework today available in MARS already allows to simulate a wide range of complex phenomena, featuring the long-term performance of ordinary and advanced cementitious materials.

  Abstract
  Predicting the time-dependent responses of concrete and concrete structures remains a challenging task in the construction sector. While experimental investigation serves [...]

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