|Concrete and Concrete Aggregates Committee Approves Two New Standards
ASTM International Committee C09 on Concrete and Concrete Aggregates has recently approved two new standards, C 1567, Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate Accelerated Mortar-Bar Method, and C 1581, Test Method for Determining Age at Cracking and Induced Tensile Stress Characteristics of Mortar and Concrete Under Restrained Shrinkage.
C 1567, which is under the jurisdiction of Subcommittee C09.26 on Chemical Reactions, is a test for evaluating pozzolans and slag for controlling alkali-silica reaction. The standard can be used to determine the level of pozzolan or slag required to control alkali-silica reaction with a particular aggregate. According to Michael Thomas, professor, department of civil engineering, University of New Brunswick, C 1567 is a modification of test method C 1260, which is strictly an aggregate test. Many agencies have been using C 1260 for years to evaluate pozzolans and slag, so there was a real need to standardize a modified version, says Thomas.
Thomas also notes that the accelerated conditions created by using the test method will produce a result in 14 days, much faster than other tests, such as C 1293, Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction, though the longer-term test is more reliable than the accelerated one.
For further technical information on C 1567, contact Michael Thomas, University of New Brunswick, Fredericton, New Brunswick, Canada (phone: 506/458-7789).
According to Heather See, project engineer, Degussa Admixtures, Inc., C 1581 will be useful for determining the relative likelihood of early-age cracking of different cementitious mixtures used in members such as overlays, floor slabs, or walls, that are restrained by adjacent structural elements. See says C 1581, under the jurisdiction of C09.68 on Volume Change, can also be used to aid in the selection of cement-based materials that are less likely to crack under restrained shrinkage.
The basis for C 1581 has been around for a long time, but only as a qualitative test method, says See. Several groups have done extensive testing for the past few years to improve and enhance the test method so that it can be used to quantify the behavior of concrete mixtures under restrained shrinkage.
For further technical information on C 1581, contact Heather See, project engineer, Degussa Admixtures, Inc., Cleveland, Ohio (phone: 216/839-7007).
Committee C09 meets Dec. 6-8 during the December Committee Week in Washington, D.C. For membership or meeting details, contact Jim Olshefsky, ASTM International (phone: 610/832-9714). //
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