What is the minimum allowable radius of the test cap used in SFRM bond strength testing?

The minimum allowable radius of the test cap used in Spray-Applied Fire-Resistive Material (SFRM) bond strength testing is specified to be 1 inch. This specification ensures that the bond strength testing is conducted in a manner that provides accurate and reliable results. A 1-inch radius allows for a proper distribution of forces applied during the test, thus facilitating an even application of stress to the material being tested.

Choosing a radius that is too small could lead to localized stress concentration and may not represent the overall bond strength efficiently. Conversely, a larger radius might also affect the integrity of the test results since it could introduce variables such as edge effects. Therefore, adhering to the minimum radius of 1 inch is crucial for standardizing results and ensuring compliance with industry standards.