ASTM D7522/D7522M-21 PDF Download

The ASTM D7522/D7522M-21 standard provides guidelines for evaluating the pull-off strength of fiber-reinforced polymer (FRP) laminate systems that have been bonded to flat concrete or masonry surfaces using adhesive.

The purpose of this standard is to establish a consistent method for preparing and testing bonded FRP systems and to evaluate and report the results. It is applicable for both field and laboratory use. The pull-off strength is an important performance property that is often used in specifications to assess the quality of FRP applications.

The standard emphasizes that variations in results can occur when different devices are used for the pull-off test. Therefore, it is recommended that the type of adhesion test device, including the manufacturer and model, be agreed upon by all parties involved.

The test method described in this standard determines the maximum perpendicular force or tension that an FRP system can bear before a plug of material is detached. The failure will occur along the weakest plane within the system, comprising the test fixture, FRP laminate, adhesive, and substrate. The results obtained from this test method can be used for quality control of adhesives and in theoretical equations for designing FRP systems to reinforce existing structures.

It is important to note that this test method is not suitable as an acceptance or proof test, as it does not determine whether an FRP system remaining intact at a prescribed force is acceptable. The standard also highlights that pull-off strength measurements depend on both material and instrumental parameters, and different devices and procedures may yield different results that cannot be directly compared.

Additionally, it should be understood that this test method can be destructive, and spot repairs may be necessary. The exposed cut section resulting from the test should be considered when determining repair methods to address potential moisture uptake. Furthermore, this test method does not provide information about the pull-off strength of the FRP from patch materials, and an additional test method is required for that evaluation.