270-CIM : Benchmarking Chloride Ingress Models on Real-life Case Studies: Theory and Practice
Technical Committee 270-CIM
Deputy Chair: Prof. Kei-Ichi IMAMOTO
Activity ending in: 2021
Focus and Objective:
Main objective of this new TC is to benchmark the currently available models on the ingress of chlorides into the concrete cover using real-life case studies. The models can be either engineering- or scientifically-based and may cover the assessment, design or engineering stage of concretes exposed to different climatic conditions, such as marine, road or near shore. The benchmark will be based on a limited variety of real-life case studies that are representative for concrete structures exposed to chloride-laden environments, and where the experimental data has been received from destructive or non-destructive testing methods. Major goal of this benchmark is to allow for a critical evaluation of the performance and applicability of chloride ingress models on their practical usability, and to identify possible gaps in accuracy, coverage and/or knowledge cross-links. The scope will be limited to reinforced concretes in cracked and/or un-cracked conditions. The proposed benchmark may serve as a reference tool for current and future generations of chloride ingress models, and it can provide academics, engineers and/or asset owners an instrument to evaluate the performance of such models used for service-life assessment. The results will be reported in a RILEM STAR report.
- Identify and select currently available engineering- and/or scientifically-based models used for chloride ingress calculations, based on a predefined set of criteria.
- Characterize each selected model, its parameters, the applications possibilities and the experience gained in these applications so far.
- Select and define a few (≈3-5) typical case studies where concretes are exposed to different typical exposure conditions and organize the experimental data in a structured manner. This includes methods of obtaining the model input parameters from experimental data received from destructive or non-destructive testing methods.
- Define the parameters and conditions for the chloride ingress models used for the benchmark.
- Simulate the chloride ingress with the engineering- and/or scientifically based models and list results in a structured manner.
- Analyse the performance of results in correlation to the parameters and model backgrounds.
- Identify potential gaps in model accuracies, differences, coverages and model limitations, and possible cross-links needs. Report the benchmark outcome and its validity to use it as a reference for future model developments on chloride ingress.
Terms of reference
The proposed time estimation for the new TC will be 5 years. During this period, objectives will be pursued by combining literature and member-based information in a STAR and to develop a framework for service-life design of concrete structures in a RILEM Recommendation. Members for the new TC will be recruited via the RILEM network, conferences and actively approached for participation. Aim is to select members from academia and industry in such a way that the full chain of the service-life of concrete structures is covered, i.e. scientists, designers, contractors, consultants, owners, and maintainers.
Detailed working programme
The new TC is aiming at organizing two regular meetings per year to adjust progress and to (re)schedule activities. At least one of these meetings will be a face to face meeting and the second one could be an internet-based conference meeting. Potential events to combine with meetings are planned as follows:
Kick-off meeting: introduction of members, suggestion of new members, overview of members’ competences and experience, plan of activities, organisation of initial workshop. Meeting will be aimed in the fall of 2016. A potential conference to meet could be the 8th International Conference on Bridge Maintenance, Safety and Management, Foz do Iguaçu (http://www.set.eesc.usp.br/iabmas2016/), 26-30 June 2016.
Listing initial results, presenting progress of first draft chapters and discussing the overall content of the STAR. A skype meeting will be scheduled in the spring and a regular meeting in the fall. The date and location of the fall meeting will be decided during the kick-off meeting.
Preparing first draft of the STAR. Lumping the chapters together and surveying the main chapter results. A potential option for a meeting would be the 72th RILEM Annual Week, Delft, The Netherlands - From 02 September 2018 to 05 September 2018.
Finishing the final chapters, finalising the STAR and discussing the final details for publishing. The meeting could be scheduled in Darmstadt, Germany.
2020 (Olympic year in Tokyo)
Finishing the committee work by summarizing the TC findings, presenting results at a special seminar of an International symposium held in Tokyo. One or more journal publications will be considered.
As this new TC is targeting to bring existing knowledge together to a working framework for service-life design of concrete structures, all currently running TCs on durability, sustainability or service-life related topics will be part of the technical environment. In particular the following committees are to be addressed:
- Technical Committee SCI: Characteristics of the steel/concrete interface and their effect on initiation of chloride-induced reinforcement corrosion (Chair : Ueli ANGST)
- Technical Committee 230-PSC: Performance-based specifications and control of concrete durability (Chair : Hans D. BEUSHAUSEN)
- Technical Committee 235-CTC: Corrosion initiating chloride threshold concentrations in concrete (Chair : Luping TANG)
- Technical Committee 238-SCM: Hydration and microstructure of concrete with supplementary cementitious materials (Chair : Nele DE BELIE)
- Technical Committee 240-FDS: A framework for durability design of fibre-reinforced strain-hardening cement-based composites (SHCC) (Chair : Gideon VAN ZIJL)
- Technical Committee 246-TDC: Test methods to determine durability of concrete under combined environmental actions and mechanical load
- Technical Committee 254-CMS: Thermal cracking of massive concrete structures (Chair : Eduardo M.r. FAIRBAIRN)
Furthermore, close collaboration is considered with fib activities, possibly leading to joint RILEM/ fib on the addressed topic. Currently running fib activities that will have a close link belong to Commission 8 on “Structural service life. fib members will be invited to participate in this new RILEM TC and possible contributions to the MC 2010 could also be considered.
Direct benefits of this new TC will be the RILEM STAR that represents a benchmark of a real-life based reference for chloride ingress models that are used in service-life assessments of concretes used in the practice. Besides this, the TC will deliver new insights on the usability of chloride ingress models for the practice and support asset owners to assess the condition of structures using models. From the STAR, optionally, modifications could be proposed for improvements of guidelines and for a proper use of chloride ingress models in the practice (by ‘engineers’).
Group of users
The group of users should contain academia, industry, governmental bodies, etc. that represent the full production chain of concrete infrastructure. In particular this will be:
- Designers, engineers and consultants who apply chloride ingress models for designing and engineering the service-life of concrete structures and to include the requirements on the concrete, design, execution, operation and maintenance stage.
- Owners of concrete structures, e.g. governmental or private developers that require a certain guarantee on performance.
- Materials suppliers that will understand better their customers’ needs, requirements and criteria for characterizing their products in view of concrete structures’ performance in time.
- Contractors may follow recommendations from the STAR to execute a construction in line with the design requirements.
- Laboratories in charge of materials testing, quality control and site monitoring will know how to conduct tests during the design, execution, operation and maintenance stage.
Specific use of the results
The result of the TC work will provide a benchmark reference that shows the performance and applicability of chloride ingress models used for service-life assessments of concrete structures. A significant economic impact will be on the fact that the benchmark will provide more insight in the usability, accuracy and reliability of chloride ingress models that are used for the future performance and associated maintenance needs of such structures. The reference tool can be used by academic s, designers, engineers and governments/industry representatives that can serve as a common basis for future scientific and or engineering developments of chloride ingress models. With this, the proposed new TC could have a major impact on the service life of concrete structures with a significant economic impact.