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[SEAOC] Reactive Aggregate[Subject Prev][Subject Next][Thread Prev][Thread Next]
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- Subject: [SEAOC] Reactive Aggregate
- From: "Hunt, Tom" <tom.hunt(--nospam--at)fluordaniel.com>
- Date: Tue, 03 Sep 1996 08:45:00 -0700
Lynn wrote: "I would like to know if anyone has some information on how we determine if coarse or fine aggregate for concrete is reactive or not." Most of the tests and limits for aggregate reactivity are shown in the Appendix to ASTM C33, Standard Specification for Concrete Aggregates. This includes the following: * ASTM C295, Practice for Petrographic Examination of Aggregates for Concrete. This is a microscopic examination of the aggregate. This is not an easy or quick test and not many laboratories can perform this test. * ASTM C289, Test Method for Potential Reactivity of Aggregates (Chemical Method). This is a quick chemical test that only takes 2 to 3 days. Test results are not entirely reliable but you can specify that results should be in the "innocuous range". * ASTM C227, Test Method for Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar-Bar Method). This is probably the best test but it takes 3 to 6 months for the results. Expansion should be less than 0.05% at 3 months and less 0.10% at 6 months. Two other tests you can ask for are ASTM 1260, Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method), less than 0.10% expansion at 16 days, and ASTM C856, Practice for Petrographic Examination of Hardened Concrete, again this test would reveal actual reactivity in the harden concrete but you must find a laboratory that is very experienced in doing this test. Regards, Thomas Hunt, S.E. ...
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