223-MSC : Masonry strengthening with composite materials

Technical Committee 223-MSC

General Information

Chair: Dr. Maria Rosa VALLUZZI
Deputy Chair: Dr. Daniel OLIVEIRA
Activity starting in: 2007
Cluster E

Subject matter

Composite materials, as FRP (Fiber-Reinforced Polymer), are increasingly used for strengthening and repair of masonry structures (buildings, bridges, towers) and structural components (walls, arches and vaults, piers and columns), even in the field of historical constructions, where preservation and restoration criteria have to be taken into account.
Beside FRP, more recently, other forms and shapes of continuous composite materials are proposed (e.g., high tensile steel wires, known as SRP/G  - Steel Reinforced Polymer/Grout), as well as various types of matrix based also on inorganic mortars (cement, hydraulic binders mixed with epoxy, ..)
Despite the ample accessibility to various products (bars, strips, laminates, sheets, grids,..), made of several reinforcing materials (fiber carbon, glass, aramid, ..; steel cords, textiles,..) and applicable in different modalities on masonry structures (embedded inside grooves or bed mortar joints, externally bonded or anchored), and despite the number of experimental and modelling works available by now in literature aimed at investigating the mechanical performances of strengthened structures, design rules of the intervention, feasibility recommendations and procedures aimed at checking the effectiveness of the technique and monitoring are not well defined yet.
In particular, the large variability of masonry typologies and constituent basic materials (brick, stones, mortar, mixed arrangements), which characterizes the existing constructions, makes more difficult the preliminary choices for proper structural models and intervention.
In this complex scenario, the preliminary work of the TC will be the systematization of the current knowledge on the structural behaviour of masonry constructions and components strengthened with composite materials (on experimental, analytical and numerical basis), in order to evidence limits and actual capability in different contexts of application, with particular care on historical environments. The support of lessons learnt from cases study and practical experiences will be also considerably taken into account. The contextual examination and comparison of the current codes available at national and international level (mainly rather new for masonry topic), the checking of their evolution and innovation, will contribute whether to evidence possible existing discordance among them (definition or relevant parameters, their influence on the evaluation of the structural models, test procedures, structural models themselves, etc..) or to confirm their reliability, in order to develop more uniform methods and basic rules for design and control.
The final aim is the possible proposal of international recommendations on the use of composite materials for the strengthening and repair of existing masonry constructions, including suitable and actual indications (design tools, quantitative and qualitative evaluation measures, limitation parameters of efficiency, simple experimental procedures) for a justified cautious approach on historical masonry.
The desirable collaboration among institutions (Universities, Public Bodies, Research Agencies), service providers and users, during the subsequent dissemination and exploitation phase, will contribute to promote and consolidate a more qualified and conscious approach towards existing masonry constructions.
Although the FRP subject in the ambit of RILEM is already present for concrete structures, the large contexts of possible applications on masonry developed in the last decade at international level may well justify a first group starting working in this field.
The here proposed TC will therefore clarify the general problems on the basis of the actual experiences, and will also point out possible developments and in-depth study of specific problems (e.g., durability, performance of particular components, bridges, use of NDT - Non Destructive Test, fire resistance, etc..) which may promote activities of further TCs focused on those aspects.
The subject will include different forms of continuous composite reinforcements (long fibres, wires, textile-like), as well as their possible combination with matrixes made of inorganic mortars.

Terms of reference

The TC is proposed to work for about 4 years, planning regular meetings (two-three per year), and additional opportunities to exchange knowledge (seminars, symposia), also in possible conjunction with the activities of the RILEM Weeks.
The committee will start as a relatively small group of experts, well representing most of the main international centres working on the subject, with collaborative and fruitful purposes.
Members will be recruited from international academic and research institutions, other RILEM TCs members working on masonry, standardization groups, Cultural Heritage administration and management, service providers and individual connections.
The work will strongly imply bibliographical research on experimental, analytical and numerical studies, on standardized methods and approaches, as well as the collection of significant cases study, for the definition of the State-of-the-Art.
Based on the systematization of experimental test results and methods, specific actions supported by possible round-robin tests will be planned, in order to select and optimize the significant parameters for the calibration of suitable behaviour models.
Particular attention will be paid to the set-up and/or the validation of simple experimental procedures, able to characterize the properties of materials and interfaces, easy to perform also in situ.

Detailed working programme

1st Year: State-of-the-Art
Data concerning the mechanical behaviour of strengthened masonry structures will be collected and grouped taking into account global performances of constructions (mainly buildings, including various typologies) and of structural components (namely walls, arches and vaults, piers and columns), as well as local aspects at interface level (bonding, behaviour of epoxy vs. inorganic mortars, effects of anchorages, different surface preparations, etc..).
For each sector, experimental procedures, analytical and numerical methods will be systemized, taking into account the various composite materials (sheets, grids, textiles) and applications on specific typologies of masonry (clay brick, stones, etc..).
Current standardized methods will be also involved in the preliminary knowledge process.
This phase will lay the basis for the definition of the technical general reference currently available at scientific level on the considered topic, so that it will be possible to discriminate procedures and methods possibly unreliable for historic constructions. Comparison with performances related to interventions using traditional materials and techniques will be included in the study.
Feasibility problems of execution on different masonry types (regular or irregular arrangement of blocks, uneven superficial finishing, level of porosity of the masonry units,...) will be also analysed, to evidence possible limitations of execution or effectiveness.

2nd Year: Calibration of methods and procedures
The systematization of the State-of-the-Art will produce a data-base for a more efficient examination of the collected information and for their mutual comparison, in order to identify the significant parameters necessary to calibrate reliable models for the interpretation of the structural behaviour, both at local and global level.
Specific round-robin tests (experimental and/or numerical) will be planned, if necessary, to clarify particular aspects of the study. The definition of simplified analysis method and experimental procedures, characterizing behaviour and properties, will be preferably pursued in this field.

3rd Year: Proposal of recommendations
A draft of proposal of international recommendations on the use of composite materials for the strengthening and repair of existing masonry constructions, taking into account the preservation problems of historical structures (compatibility with the substrate, reversibility, ...), will be developed on the basis of the results of the previous phases. Guidelines should give detailed information on methods and their reliability in different masonry contexts, for the proper design of the interventions and the control of their execution and effectiveness through non-destructive tests.
Strategies for intervention choices in the field of historical constructions with innovative materials as composite products will represent a fundamental part of the document.

4th Year: Dissemination of knowledge
The last year will be devoted to the finalization of the previous phases and, in particular, of the recommendations document, by the possible discussion and calibration during workshops planned to be open to users, industrial and professional people and service providers. Dissemination of results will be performed by seminars to be organized in educational and professional institutions. Training courses will be also provided, taking care to demonstrate effective limits and potentials of the various applications and of the checking methods.

Technical environment

The proposed TC will contribute to clarify scientific aspects concerning the strengthening of existing masonry structures with innovative materials, particularly in the field of historic constructions. Other active TCs correlated to the subject are: RHM (repair mortars for historic masonry, chaired by G. Groot), SAM (strategies for the assessment of historic masonry structures with NDT, chaired by L. Binda), and FRP (FRP-concrete bond in structural strengthening and rehabilitation, chaired by Banthia). All the mentioned TCs are included in the RILEM cluster E (special construction materials and components, whose convener is L. Binda).
Moreover, the TC integrates the standardization and recommendation groups which have been or are still active in the field of the application of FRP and composite materials on structures (mainly concerning r.c.), both at national and international level.

Expected achievements

The following results will be pursued:
- State-of-the-Art on experimental procedures and modelling methods for the characterization of the mechanical behaviour of masonry structures and components strengthened with FRP materials
- Data-base of the results obtained for different composite materials (both fibers and matrices) and types, masonry typologies, structural components and assemblages, local behaviour, descriptions of cases study
- Harmonized experimental procedures and modelling methods to characterize material properties and structural behaviour
- RILEM guideline recommendations for the proper application of innovative materials on existing masonry structures, including specific aspects for historic constructions (design, execution and control by NDT)
- Workshops/symposia to integrate contribution from users, industrial and professional people, and service providers
- Seminars and training courses.

Group of users

Testing laboratories, academics, industrial and professional people, managers of Cultural Heritage, service providers and general users of masonry structures and Cultural Heritage buildings.

Specific use of the results

The use of innovative materials and techniques on existing masonry structures needs specific systematizations, in the light of the remarkable scientific developments now available at international level. In this connection, preservation and management of Cultural Heritage is a topical subject in many countries, especially when seismic risk or other severe hazardous causes of damage are present. Efficient and aware intervention solutions on existing constructions maintain continuous functioning and use and reduced maintenance costs. NOW AVAILABLE Apply for the MSC Data-Warehouse: you can contribute to enhance the tool for data storage and analysis on Masonry Strengthening with Composite materials at https://rilem223dwh.isqweb.it/