Rationale

Work Item: Revision of ASTM C1778 – Revise Fig. 1 – Flow Chart, revisions to Section 6 Procedure, and Section 7 Determining Aggregate Reactivity.
Rationale: During the ASTM C09.50 Spring 2024 Meeting in Philadelphia, there was discussion to withdraw or revise Work Item WK 88785, the ballot to remove the Flow Chart - Fig, 1. This was based upon the significant number of negative votes received on the ballot.
To address the concerns that prompted the work item, there was discussion to revise Fig. 1, making all the lines solid. This work item proposes to change the dotted lines in Fig. 1, making all the lines solid, and to add revised wording. The intent of this proposed revision is to encourage users of these document to further review the text within this guide to facilitate:
1. A better understanding of the information that can be gained from each one of the listed methods, and the concerns with using those methods individually.
2. To provide the user with a comprehensive view of the current state of knowledge for evaluating an aggregates potential for deleterious ASR.
3. To encourage users toward a though multi step approach to evaluate potential aggregate reactivity. One that is consistent with the level of risk associated with deleterious ASR for their project.
Without reviewing the text of the document, the user can leave without an understanding of the context within, that has been carefully developed through a discussion of the methods for assessment of the ASR potential of an aggregate, establishing levels of risk, and selecting mitigation approaches. When this occurs the role of this document, as a guidance document, fails. In reviewing current ASR specifications in practice, and working to meet these, it is apparent that this happens all too frequently. The document, while meant as a guide, is being inserted as a must follow specification into project contract documents without proper understanding of the text within.
The practice of using this guide without understanding the context and details within, has produced published project specifications that have resulted in serious issues including:
? Sole reliance on ASTM C1260 test results. This has allowed aggregates with false negatives to be put in service, resulting in significant expense to replace pavements and structures within a few years following their construction.
? Specifications that preclude the use of aggregates classified as moderately reactive from being used into non-exposed or non-critical applications, and where the mitigation measures noted would be effective.
? Mitigation requirements over and above what is recommended in this guide for the appropriate level of risk or exposure of the concrete construction element. This has resulted in an increase in scaling and constructability issues.

There is a habit within our industry to rely on a single recent laboratory test to provide a quick yes or no, good or bad, pass or fail result to qualify our construction materials. The complex nature of determining the potential for deleterious ASR and if required, proper mitigation is challenging enough utilizing the current approved methods. Not reviewing and understanding the benefits and limitations of these methods encourages this short-sighted practice.
ASTM C1778 is recognized as the source for the most current state of knowledge on ASR, and to be used as a reference for preparation of construction specifications. By helping to promote a wider understanding of the complex issue of assessing the potential for deleterious ASR by requiring users to read the guide, and therefore specify appropriate mitigation measures with respect to risk and constructability concerns.

Note: Sections 1. Scope, 4. Summary of Guide, and 5. Significance and Use, are included in this ballot for reference during review of this work item, however no changes are proposed. Section 7 determining aggregate reactivity is included in its entirety although changes are only proposed to sections 7.7.1 and 7.7.3.