255-FRS : Fire resistance of concrete structures repaired with polymer cement mortar
Technical Committee 255-FRS
Deputy Chair: Prof. Kei-Ichi IMAMOTO
Activity ending in: 2019
Recently, the rapid deterioration of the reinforced concrete structures due to chloride-induced corrosion, alkali-aggregate reaction and early carbonation has become a serious problem. The polymer cement mortar (PCM) which is produced by mixing polymeric admixtures with cement mortar is currently used in large quantities as a popular repair material for the deteriorated reinforced concrete structures because of its high flexural and tensile strengths, strong adhesion to cement concrete, waterproofness, airtightness and durability. PCM is considered to be a good patch material for deteriorated reinforced concrete structures exposed in severe environmental conditions. Although cement mortar and concrete are conventionally used as fire resistance materials, the existence of polymer might reduce the fire preventive performance of the cement mortar and concrete, which sometimes causes the spalling of the PCM. Fire resistance of the PCM as part of cover concrete plays an important role in the durability and structural performance of deteriorated concrete structures.
This RILEM Technical Committee will conduct scholarly activities towards developing deeper fundamental understandings of the mechanisms of spalling of PCM under fire and of the mechanical properties of reinforced concrete member repaired with PCM, and establish test methods to evaluate their fire resistance.
Terms of reference
The activities of the new TC are proposed to be conducted over a 5-year time period. Members will be recruited from academia and industry, based on their experience with PCM, concrete and fire.
The work will include literature research, exchange of good practices information, journal publications and/or state-of-the-art report regarding the following items;
Properties of PCM
- Thermal conductivity
- Thermal expansion coefficient
- Mechanisms of spalling
- Fire resistance
- Mechanical properties at high temperature
Structural behaviour of RC member repaired with PCM
- Flexural performance of beam and slab
- Structural performance of column
- Method to keep the bond between PCM and structural concrete
- Prevention method for fire spalling of concrete structures
- Incombustibility of PCM
- Spalling resistance of PCM
- Fire resistance of member
Detailed working programme
- start-up meeting (2013): introduction of members, suggestion of new members, overview of members’ competences and experience, plan of activities, organisation of initial workshop
- small workshop for the members (2014), in order to get an overview of experience, problems and points of attention related to PCM and concrete members repaired with PCM; decision on most important points for further TC work
- next workshop and exchange of information between TC members (2015); compilation of sheets with the best available technique and the best practices; round robin test if appropriate
- international symposium (2016)
- summary of TC findings in one or more journal publications, STAR and/or recommendation of test methods (2017)
The study of the new TC fits into the scope of RILEM as an organisation dealing with a range of construction materials and structural performance. The work will be an extension of the previous TCs which relate to PCM and RILEM TC 227-HPB.
Expected benefits are:
- publication of the state-of-the-art report
- improvement of the knowledge related to the mechanisms of spalling of PCM and the prevention method for spalling of PCM from concrete structures.
- establishment of test methods to evaluate the fire resistance of PCM and concrete member repaired with PCM.
- establishment of network among researchers working in the field of PCM and fire-resistant construction materials.
Group of users
Academics, testing laboratory workers, industrialists, practitioners
Specific use of the results
- Establishment of ISO standard
- Establishment of standard test method and common criteria
- Clarification of technical targets
- Proper communication between users and providers of PCM
Extending the life time of the concrete structures is quite important. PCM as a patch material contributes this trend. Best practices related to the study of concrete with PCM will lead to new materials and practices.