191-ARP : Alkali-reactivity and prevention - Assessment, specification and diagnosis of alkali-reactivity

Technical Committee 191-ARP

General Information

Deputy Chair: Dr. Ian SIMS
Activity starting in: 2000
Cluster D

Subject matter

The proposed new TC will develop an integrated assessment, specification and diagnosis procedure for alkali-reactions in concrete, building on the important and valued work of TC-106 in developing accelerated test methods for alkali-aggregate reactions in concrete. The test methods already developed by TC 106 will be integrated into a coherent assessment system. Additionally, guidance will be prepared on the reliable diagnosis of damage from alkali-reactions and guidance on the principles and options for the specification of concrete to avoid such damage. Liaison will be maintained with CEN TC154 (aggregates) and with the EU 'STAR' consortium who are evaluating the TC-106 recommendation as the basis for CEN methods of test.

Terms of reference

The proposed work programme is for a 5 year period. Members will be primarily recruited from international experts in alkali-reactions, many of whom have been active in TC-106. A large and internationally representative membership is still seen as an advantage in achieving acceptance and universal application of the RILEM Recommendations. This is particularly important for this subject, given the wide geological variations in the nature of he problem and the current great diversity of test methods. It is important that the RILEM Recommendations actually introduce a harmonisation of test methods and do not just add to the confusion. However, it is appreciated that a large membership can be unwieldy, so that greater use will now be made of the 'corresponding member' status and a new 'liaison' membership, keeping the active membership within the new RILEM guidelines. The membership will include the research community, testing laboratories, practising engineers, materials consultants and representatives of national or trade organisations. It is anticipated that the active and corresponding members of the TC will be subscribing members of RILEM. The work of the committee will include the identification of reference materials, round robin testing and a 'workshop' approach to the harmonisation of assessment and diagnosis.

Detailed working programme

i) Finalise RILEM TC 106-2 & TC 106-3 as RILEM AAR-2 & AAR-3 respectively ii) Complete method of petrographic examination for AAR assessment (RILEM AAR-1) · edit and redraft, especially adding guidance on carbonates · circulate for ballot · revise in light of ballot & comments received · publish as RILEM Recommendation iii) Accelerated (60º) Concrete Performance Test (RILEM AAR-4) · redraft and circulate with request for views and information on local suitability · organise round robin trial using reference aggregates and local combinations · evaluate results of round robin trial at 2001 meeting · redraft and publish as RILEM Recommendation iv) Alkali-Carbonate Reaction · draft RILEM Recommendation(s) for initial assessment and expansion tests · consider draft at 2001 meeting · redraft and publish as RILEM Recommendation(s) v) Guide to Reference Cement and Aggregate · revise to include reference carbonate aggregate & specialised test accessories · prepare as appendix to the Guide to the use of RILEM methods (below) vi) Guide to the Use of RILEM methods (RILEM AAR-0) · revise to include classification guidance, flow chart and reference annex · circulate for ballot and publish as RILEM Recommendation vii) Survey of Test Methods in Use (incorporated into RILEM AAR-1) · maintain and circulate test methods vii) On-going Review of International Developments in AAR Assessment · identify & review research developments · identify & review new or revised national test methods & specifications viii) Reliable Method for Assessing Alkalis Releasable from Aggregate · further develop guidance and draft methods · revise and publish as RILEM Recommendation ix) Reliable Diagnosis of Damage to Concrete caused by AAR · prepare guidance on principles and methods of diagnosis · publish as RILEM Recommendation x) Guidance on the Specification of Concrete to Avoid Damaging AAR · prepare guidance on principles and options for specification · publish as RILEM Recommendation xi) Final Presentation of Authoritative International Guidance as a RILEM Book · co-ordinate guidance prepared by TC 106 and proposed new TC · draft an edited book, to provide comprehensive and coherent guidance · complete and publish as a RILEM book

Technical environment

The proposed new committee would build on the previous work of TC-106 and would therefore have full access to its knowledge and experience. The TC would maintain strong liaison with CEN TC154 (Aggregates) who are mandated by the EU to develop limits and specifications for alkali-reactivity. It would also maintain strong liaison with the EU 'STAR' consortium who are evaluating the RILEM TC 106 Recommendations as the basis for CEN methods of test. Importantly, the proposed new TC would also further develop the links recently established between TC 106 and the influential ASTM, CSA and AASHTO organisations in North America, as well as seeking liaison with other related RILEM TCs (hopefully including a separate TC dealing with the structural engineering aspects of alkali-reactions in concrete).

Expected achievements

The expected achievements are harmonised guidance and test methods in the form of RILEM Recommendations. These are urgently needed as currently there is a plethora of conflicting and contradictory methods in use around the world. TC 106 has already published two methods as RILEM Recommendations and these would be finalised as parts of a separate 'AAR-' series. As a major contribution to international harmony in combating alkali-reactivity in concrete, the achievements of both TC 106 and the proposed new TC would eventually be formulated into a published RILEM book.

Group of users

Primarily materials suppliers, testing laboratories and consulting engineers or materials scientists.

Specific use of the results

Initially the specific use of the results will be to provide a set of internationally agreed test methods that an engineer working anywhere in the world can apply and interpret with confidence. The method may then be adopted as the basis for CEN and perhaps ISO methods of test. Their primary purpose here will be to facilitate freedom of trade, which is at present often hindered by the lack of harmonised test methods.