|ASTM Concrete Committee Seeks Aggregates Stakeholders to Develop Dry-Condition Standard
Subcommittee C09.20 on Normal Weight Aggregates is forming a task group to draft a Standard Practice for Determining the Dry Condition or Constant Mass of Aggregates Used in Concrete. Part of ASTM Committee C09 on Concrete and Concrete Aggregates, the subcommittee seeks experienced aggregates testers, users, specifiers, and other stakeholders to develop the standard.
The participants should be involved with the testing of aggregates, should have the facilities and interests to verify the correctness of the procedures suggested in the practice, and should be acquainted with procedures for ASTM standards development, says committee member Ralph Vogler, a civil engineer who spent 37 years supervising the testing of highway construction materials with the Michigan Department of Transportation before he retired.
Vogler explains the benefits of developing the proposed standard, speaking on behalf of Committee C09, in which he has been active since 1966. Many standards have requirements for drying a material (aggregates, concrete, soils, etc.) to a constant mass (commonly referred to as oven-dry condition), he says. We are not aware of any current procedure that enumerates the variables in determining when constant mass has been achieved.
Failure to properly determine the oven-dry condition can affect the appropriate determination of the absorption of an aggregate, resulting in the incorrect determination of the mass to be batched in a concrete mix, he continues. It can result in incomplete removal of moisture in the sulfate soundness test, so that the test is not conducted by the intended procedure, and the true result is not achieved. In testing concrete specimens, failure to properly dry can result in approval of concrete blocks that have greater than the permissible amount of absorption, which can lead to freeze-thaw deterioration.
When drafting the standard, the task group will recommend the following variables to be considered:
(a) The time interval between determinations of the mass;
(b) The amount of change in mass that is considered to be insignificant (in determining the final mass);
(c) The effect of differing quantities of material (one 1000-g sample vs. twenty 1000-g samples) in the drying oven;
(d) The effect of the size of particles that are being dried (for example, 2 mm or 200 mm diameter); and
(e) The permeability of the material.
To join the task group or obtain further technical information, contact Vogler in Jackson, Mich. (phone: 517/784-9843). Committee C09 meets Dec. 7-10 in Tampa, Fla. For membership or meeting details, contact Jim Olshefsky, director, Committee Services, ASTM International (phone: 610/832-9714). //
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