Which SFRM testing method is specifically designed for bond strength assessment among the choices available?

The pull-off testing method is specifically designed for assessing bond strength in Spray-applied Fire-Resistive Materials (SFRM). This technique involves placing a small, circular test disc onto the surface of the SFRM, typically using an adhesive, and then applying a force to pull the disc away from the substrate at a controlled rate. The maximum force recorded during this process indicates how well the fireproofing material adheres to the surface underneath.

This method is crucial because it directly measures the bond strength, which is an essential factor for the effectiveness of fireproofing materials in protecting structural elements during a fire. A strong bond ensures that the SFRM remains intact and provides the necessary fire resistance, preventing spalling or detachment that could compromise structural integrity.

Other methods listed serve different purposes; for instance, the displacement method is generally used for assessing material expansion or contraction rather than bond strength. Compression testing assesses material strength by applying pressure, while visual inspection is focused on surface condition and does not quantify bond strength. Thus, pull-off testing stands out as the targeted approach for evaluating the adhesion performance of SFRM.