Pull-Off Test

Pull-off testing is a semi-destructive method used to evaluate the in-situ tensile strength of concrete and the bond quality between concrete and applied materials, such as repair mortars, overlays, and protective coatings.

The test provides a direct measure of tensile resistance by applying a controlled tensile force perpendicular to the concrete surface until failure occurs.

The test is widely used for:

  • quality control,
  • condition assessment, and
  • acceptance of concrete repairs in structural, industrial, and infrastructure applications.

Concept of Pull-Off Test

The pull-off test measures the force required to detach a bonded steel disc (dolly) from the concrete surface.

  • A circular steel dolly is bonded to the concrete using a high-strength adhesive

  • The concrete may be cored around the dolly to isolate the test area

  • A hydraulic or mechanical pull-off device applies a tensile load normal to the surface

  • Load is increased at a controlled rate until failure occurs

  • The maximum applied force is recorded

The pull-off strength is calculated as:

Pull Off Stress = P/A

Where:

  • P = maximum applied load (N)

  • A = dolly area (mm²)

Pull-Off Test Concrete

Key Steps

  • Surface preparation and cleaning

  • Bonding of the steel dolly using approved adhesive

  • Optional coring around the dolly to a specified depth

  • Attachment of the pull-off test device

  • Application of tensile load at a controlled rate

  • Recording of maximum load and observation of failure mode

Multiple tests are performed to ensure representative results.

Key Deliverables

A pull-off testing program typically provides:

  • Pull-off tensile strength values (MPa or psi)

  • Identification of failure mode (adhesive vs cohesive)

  • Statistical summary of test results

  • Comparison with project acceptance criteria

  • Engineering interpretation and recommendations

Applicable Standards and Guidance

Pull-off testing is governed by established standards:

  • ASTM C1583/C1583M – 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)

  • ACI 546R – Guide to Concrete Repair

Please contact us for a free quotation and tell us more about your project

Thank you for your interest in requesting a work estimate, please fill out the form and we will get back to you shortly.
Image