213-MAI : Model assisted integral service life prediction of steel reinforced concrete structures with respect to corrosion induced damage
Technical Committee 213-MAI
Deputy Chair: Joost GULIKERS
Activity ending in: 2012
Concrete structures may be very durable but their ageing is still a matter under study due the economical consequences of the maintenance, assessment and repair. Corrosion of reinforcement is the most detrimental process in the structural ageing. The subject of service life modeling is a very complex matter and numerous researchs are underway to try to find a comprehensive approach. Some previous RILEM TC’s have dealt with the subject and prepared important reports (TC-104-DDC, “Damage Classification of Concrete Structures,”, TC-130 “Service life prediction”, TC-154-“Electrochemical Techniques For Measuring Corrosion In Concrete”, TC 160-MLN, “Life Prediction of Concrete Structures in Nuclear Power Plants” and TC-178: “Testing and modelling chloride penetration into concrete”) although they were devoted to specific aspects of the service life prediction. A comprehensive modeling comprises the ability: a) of prediction the penetration of the aggressive substances in a particular environment either in the phase of designing of the structure or when it has been built, b) the evolution of the corrosion once it has been developed in the reinforcements and c) the structural behavior when cracking has started. The modeling of the penetration of chlorides and carbonation has attracted most of the interest in the past years although an aspect as the chloride threshold, from an engineering perspective, remains controversial. The corrosion leads to cracking of concrete cover and to a loss of steel/ concrete bond and of the load-bearing capacity of the structure, which has been scarcely treated in a rigorous form. Therefore the modeling of the structural performance when the corrosion has been developed is an important aspect to be considered by the TC. On the other hand, the modeling can be assisted by testing of the particular concrete or can be monitored by the use of embedded sensors. The objective of the TC-MAM will be the preparation of a State of the Art Report on existing models for both the design phase or for existing structures damaged by corrosion structures as well as the compilation of tests and sensors suitable to be used in practice for such modeling. Another objective will be the preparation of a Rilem Recommendation for the guidance of users of service life models.
Terms of reference
The main scope of the TC is studied at present in many countries and by many regional and international associations (fib, ACI, IABSE, etc). Work previously made in RILEM by other TC’s (TC-60-“Corrosion of steel in concrete”, TC-104-DDC, “Damage Classification of Concrete Structures,”, TC-130 “Service life prediction”, TC-154-“Electrochemical Techniques For Measuring Corrosion in Concrete”, TC 160-MLN, “Life Prediction of Concrete Structures in Nuclear Power Plants” and TC-178: “Testing and modelling chloride penetration into concrete”) in the subject of reinforcement corrosion will be a starting point. There are at present in Rilem some related activities although they are broader and not focussed to reinforcement corrosion so specifically ( TC- LTP Prof. Dr. Asko Sarja: Life time performance of materials and structures and TC-INR Prof. Denys Breysse: Interpretation of NDT results and assessment of RC structures) .Due to the recognized importance of the subject and the long tradition of Rilem in it , it seems necessary to address the review and give guidance to designers and users of the models, as well as to identify the gaps in the knowledge, in order to propose the aspects that need further research. In particular the work of this Committee will try to stimulate the preparation of new ones in the field.
Detailed working programme
The starting point will the collection of existing models devoted to reinforcement corrosion. Review will be undertaken regarding other committees, existing guides and recommendations of Administration Authorities (mainly Road and Transport), results of research projects, existing Manuals (Contecvet), Rilem Reports and published literature.
Activities will be developed over a five year period although some of the activities may be closed before in order to enable the presentation of new committees in the speciality.
The Committee will be subdivided in the following topics:
a. Models for chloride and carbonation penetration in the design phase and models for the propagation period
b. Chloride threshold and limit state of corrosion
c. Structural modeling of corroding structures
d. Testing instrumentation and monitoring methods for use in the assessment of corroding structures
Subcommittees will be established to address the above four topics. It is foreseen that this Committee could serve for stimulating the creation of other related ones having more specific objectives.
The proposed members are academic, researchers and some designers. Some of them are end users of the models. On the other hand, the technical committee would build on prior related work conducted under RILEM committees, would involve interdisciplinary fields that are linked with the “core business” of RILEM ; and would utilize developments of several existing RILEM committees.
As main outcomes from the TC is foreseen:
- A State of the Art Report on existing models and identification of needs in needs of research in the area
- A Rilem Recommendation on guidance for users of models of reinforcement corrosion
Other activities foreseen are:
- An international workshop in 2007.
- An international conference in 2008 to present the State of the Art Report
Group of users
This TC will address researchers in the field designers of advanced structures and public or private owners needing to manage special structures. They are either developers of the models or end users.
Specific use of the results
Results of this TC will have application in the management of aging of concrete and concrete structures from the particular aspect of the reinforcement corrosion. The critical analysis that is attempted to be made on the existing models will help to improve them and select the most rational. Regarding the economical impact, an application of the results of this TC can potentially result in reduced costs through use of improved materials and design methods, increased understanding of degradation parameters, and guidance on performance monitoring, while effecting improved safety and reliability.