5.1 This test method determines the tensile strength of concrete near to the prepared surface, which can be used as an indicator of the adequacy of surface preparation before applying a repair or an overlay material.

5.2 When the test is performed on the surface of a repair or an overlay material, it determines the bond strength to the substrate or the tensile strength of either the overlay or substrate, whichever is weaker.

5.3 The method may also be used to evaluate the adhesive strength of bonding agents.

5.4 When the test is performed on the surface of a material applied to the substrate, the measured strength is controlled by the failure mechanism requiring the least stress. Thus it is not possible to know beforehand which strength will be measured by the test. For this reason, the failure mode has to be reported for each individual test result, and tests results are averaged only if the same failure mode occurs.

This specification covers standard test method for tensile strength of concrete surfaces and the bond strength or tensile strength of concrete repair and overlay materials by direct tension (pull-off method). This test method is suitable for both field and laboratory use to determine one or more of the following: the near-surface tensile strength of the substrate as an indicator of the adequacy of surface preparation before application of a repair or overlay material; the bond strength of a repair or an overlay material to the substrate; and the tensile strength of a repair or overlay material, or an adhesive used in repairs, after the material has been applied to a surface. The following apparatus shall be utilized: core drill; core barrel; steel disk; tensile loading device; and a coupling device. This test shall be performed on the surface of a prepared concrete base before application of a concrete repair overlay material, or on the surface of a concrete repair overlay material after the material has been applied to the prepared concrete surface. The test specimen shall be formed by drilling a shallow core into and perpendicular to the surface of the substrate, and leaving the intact core attached to the concrete. A steel disk shall be bonded to the top surface of the test specimen. A tensile load shall be applied to the steel disk until failure occurs. The failure load and the failure mode shall be recorded and the nominal tensile stress at failure shall be calculated.

1.1 This test method is suitable for both field and laboratory use to determine one or more of the following:

1.1.1 The near-surface tensile strength of the substrate as an indicator of the adequacy of surface preparation before application of a repair or overlay material.

1.1.2 The bond strength of a repair or an overlay material to the substrate.

1.1.3 The tensile strength of a repair or overlay material, or an adhesive used in repairs, after the material has been applied to a surface.

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.3 The text of this standard refers to notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this standard.

1.4 This standard does 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.