ASTM Announces New Concrete Development

TUESDAY, JUNE 20, 2023


ASTM International’s concrete and concrete aggregates committee (C09) has reported that they are currently developing a standard to evaluate the tensile performance of fiber-reinforced concrete using “cylindrical specimens with double-punch loading.”

The method is reportedly based on the double-punch test method (DPTM), the process of loading a cylindrical specimen “with a length-diameter ratio of 1” into a compression testing machine through 1.5-inch diameter holes at the end.

“The double-punch test, outlined in the proposed standard, utilizes a simple apparatus and procedure, providing a convenient method for obtaining these tensile properties. This test method is well-suited for routine testing purposes and exhibits low variability in its results,” said Shih-Ho (Simon) Chao, a professor of civil engineering at the University of Texas at Arlington and member of ASTM.

According to Chao, the DPTM is reportedly highly regarded since it has undergone extensive testing by researchers across the world.

The new proposed standard will reportedly contain “pre- and post-peak tensile properties (that) hold great significance in fiber-reinforced concrete (FRC) and ultra-high-performance concrete (UHPC). These properties serve as the fundamental characteristics of FRC and UHPC, playing a vital role in determining the capacities and failure modes of structural members constructed from these materials,” said Chao.

Chao added that FRC and UHPC can provide better durability over traditional concrete, which he states “has the potential to encourage the adoption of these durable materials, thereby promoting sustainable development within society, particularly in terms of sustainable infrastructure."

Chao states that this could serve as a helpful tool for quality control purposes, as well as to guide “for serviceability and strength design.”

Standard Background

This announcement follows the committee’s previous announcement from earlier this year when ASTM initially began tests to evaluate the performance of fibers in concrete.

According to the release, the effort directly related to the United Nations Sustainable Development Goal #9 on industry, innovation and infrastructure.

“Typically, tensile capacity of concrete is ignored when designed with reinforced concrete,” said Luke Pinkerton, ASTM International member. “Being able to measure tension accurately would give engineers the confidence to use the tensile strength rather than ignore it. Concrete with fiber reinforcement is stronger, less brittle, more durable, and resilient.”

The scope of the “New Practice for Direct Tension Testing of Fiber Reinforced Concrete” focused on three key points:

  • This practice evaluated the direct tension performance of fiber-reinforced concrete using parameters derived from the load-displacement curve, which is obtained by testing a tensile coupon under direct tension loading using a closed-loop, servo-controlled testing system. This practice provided for the determination of a load-versus-displacement curve. The results may be normalized based on the number of fibers in the broken specimen cross section;
  • The values stated in either SI units or inch-pound units were to be regarded separately as standard. The values stated in each system should not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the practice; and
  • This practice did not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

The draft standard also noted that there was no ASTM standard to measure this fundamental property of fiber-reinforced concrete, and tension can only be determined indirectly through flexural testing.

ASTM further explained that a direct testing method would be needed to give the engineering community the data and confidence needed to evaluate performance of fibers. Additionally, the Committee added that direct tension testing methods were under development in other countries by competing standards organizations and the development of a direct tension method would help maintain ASTM as a leader in the field.

   

Tagged categories: Asia Pacific; ASTM; Building materials; Certifications and standards; concrete; Concrete coatings and treatments; EMEA (Europe, Middle East and Africa); Latin America; North America; Ongoing projects; Program/Project Management; Testing + Evaluation; Z-Continents

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