ASTM D7522/D7522M-21 PDF

Full title and description

ASTM D7522/D7522M-21 — Standard Test Method for Pull-Off Strength for FRP Laminate Systems Bonded to Concrete or Masonry Substrates. This test method describes apparatus and procedures to determine the greatest perpendicular tensile force that an adhesively bonded fiber-reinforced polymer (FRP) laminate system can sustain before a plug of material is detached from a flat concrete or masonry substrate; it applies to wet lay-up and pultruded (shop-fabricated) FRP laminate systems bonded to substrates.

Abstract

This standard specifies a field and laboratory pull-off (direct tension) test for assessing bond performance of FRP laminate systems bonded to concrete or masonry. The method defines specimen preparation, bonding of the test fixture (steel disk), loading procedure and reporting of failure modes (substrate, adhesive, laminate or interface). The standard clarifies units (SI and inch-pound) and notes limitations for testing FRP adhered to patch materials (an additional method is required for the patch-to-substrate bond).

General information

• Status: Active standard (current edition approved 2021; revision activity has been initiated by ASTM subcommittee D30.10 in later work items).
• Publication date: January 1, 2021 (designation D7522/D7522M-21).
• Publisher: ASTM International.
• ICS / categories: 91.100.40 (Products in fibre‑reinforced cement / composites for civil structures).
• Edition / version: D7522/D7522M‑21 (metric and inch‑pound designation paired in one document).
• Number of pages: 6 pages (short test method format typical of pull-off procedures).

Scope

This test method covers the apparatus and procedure for evaluating pull-off strength of wet lay-up or pultruded FRP laminate systems adhesively bonded to a flat concrete (or masonry) substrate. The test determines the maximum perpendicular tensile force that causes a plug to be detached and records the failure plane(s) within the system (fixture, laminate, adhesive, or substrate). The method is not intended to determine the pull-off strength of FRP from a patch material; a separate test is required for patch-to-substrate bond assessment. Units are given in both SI and inch‑pound systems and each system is to be used independently.

Key topics and requirements

• Purpose: measure perpendicular (tensile) pull-off strength of bonded FRP laminate systems.
• Applicable FRP types: wet lay-up and pultruded (shop-fabricated) laminates.
• Specimen preparation: core/drill test plug, bond steel disk (dolly) to FRP, allow adhesive cure per procedure.
• Test apparatus: calibrated pull-off tensile loading device (adhesion tester) and coupling device to apply direct tension.
• Reporting: failure load, nominal tensile stress at failure, and description of failure mode (substrate, adhesive, laminate, interface).
• Units: both SI and inch‑pound units specified; do not combine values from both systems.
• Limitations: not suitable for assessing FRP-to-patch bond strength; safety and site‑specific considerations are responsibility of the user.

Typical use and users

Used by materials laboratories, structural and civil engineers, inspection and quality‑control personnel, FRP contractors and specifiers to assess field or laboratory bond performance of FRP strengthening systems applied to concrete or masonry. Common applications include evaluation of installation quality, verification of adhesive/installation performance, acceptance testing of repairs/strengthening, and research or comparative testing of FRP systems.

Related standards

Closely related to other pull‑off/direct‑tension test methods such as ASTM C1583/C1583M (tensile strength of concrete surfaces and bond strength of repair/overlay materials by direct tension), and other ASTM D30 committee documents covering composites for civil structures; users often refer to C1583 when comparing pull-off test methods and test rates. Recent ASTM work items have proposed revisions to D7522/D7522M to align loading/test rate language with C1583/C1583M practices.

Keywords

pull-off strength; pull-off test; FRP laminate; fiber-reinforced polymer; adhesive bond; concrete substrate; masonry substrate; wet lay-up FRP; pultruded FRP; bond strength; direct tension; dolly; tensile tester; failure mode; ASTM D7522.

FAQ

Q: What is this standard?

A: ASTM D7522/D7522M‑21 is a standard test method that defines a pull-off (direct tension) procedure to measure the perpendicular tensile (pull-off) strength of FRP laminate systems adhesively bonded to concrete or masonry substrates.

Q: What does it cover?

A: It covers apparatus, specimen preparation, loading procedure, units (SI and inch‑pound), test execution and reporting, and guidance on identifying the failure plane(s) within the FRP/adhesive/substrate system. It explicitly notes it is not intended to evaluate pull-off strength of FRP from a patch material — a separate method is required for patch-to-substrate bond.

Q: Who typically uses it?

A: Structural and materials engineers, testing laboratories, contractors installing FRP strengthening systems, inspection and quality assurance personnel, and researchers comparing FRP adhesive or installation performance.

Q: Is it current or superseded?

A: The D7522/D7522M‑21 edition was approved and published in 2021 and is listed as the active edition; ASTM subcommittee D30.10 has since initiated work items to revise the method (balloting activity was recorded in subsequent work items), so users should confirm the current status with ASTM if a later revision has been published.

Q: Is it part of a series?

A: It is part of ASTM’s suite of test methods for bonded materials and composites under Committee D30 (Composites) and is presented with a paired metric/inch‑pound designation (D7522/D7522M). It is commonly cross‑referenced with pull‑off methods such as ASTM C1583 for related bond and tensile surface testing.

Q: What are the key keywords?

A: pull-off, pull-off strength, FRP, adhesive bond, concrete substrate, masonry substrate, dolly, tensile tester, wet lay-up, pultruded FRP, bond strength, failure mode.