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Supporting Rollers

Laboratories and manufacturers of equipment used to test the flexural performance of concrete will be the primary users of a proposed new ASTM standard for supporting rollers. WK42757, Specification for Supporting Rollers Used in Fiber-Reinforced Concrete Beam Tests, is being developed by Subcommittee C09.42 on Fiber-Reinforced Concrete, part of ASTM International Committee C09 on Concrete and Concrete Aggregates.

WK42757 will describe the design of suitable supporting rollers to be used in beam tests conducted to assess the post-crack performance of a fiber reinforced concrete mixture. Included in the proposed practice will be drawings and dimensions of the rollers, the type of material the rollers are to be fabricated from and operation of the rollers during a test. The practice will also include a method for correcting test results to account for a constant, relatively low degree of friction that rollers exhibit during a test.

According to Stefan Bernard, managing director, TSE Pty Ltd., and a C09 member, once it has been approved, WK42757 will be used in conjunction with C1399/C1399M, Test Method for Obtaining Average Residual Strength of Fiber-Reinforced Concrete, as well as C1609/C1609M, Test Method for Flexural Performance of Fiber-Reinforced Concrete (Using Beam with Third-Point Loading). Bernard notes that evidence from testing shows that friction in rollers can cause a bias in the modulus of rupture obtained at first crack, so rollers covered by the proposed practice might also be applicable for use with C78, Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading).

All interested parties are invited to take part in the ongoing development of WK42757. Bernard says that this participation could take the form of evaluating the effect of friction on rollers on the apparent flexural strength of plain concrete, since tests have so far been limited to fiber reinforced concrete.

CONTACT Technical Information: Stefan Bernard, TSE Pty Ltd. • Sydney, Australia • Phone: 224-725-5801 | ASTM Staff: Scott Orthey • Phone: 610-832-9730 | Upcoming Meeting: Dec. 9-11 • December Committee Week • Jacksonville, Fla.

This article appears in the issue of Standardization News.