What type of failure occurs when a sealant does not adhere properly due to the weakness of the concrete surface?

The correct response pertains to substrate failure, which refers to the situation where the underlying material, in this case, the concrete surface, is unable to adequately support or bond with the sealant. This inadequacy can occur due to various factors, such as surface irregularity, contamination, or degradation of the concrete itself. When the concrete cannot provide a solid foundation for the sealant, it leads to a situation where the bond is compromised, resulting in ineffective sealing and potential leakage.

Understanding substrate failure is crucial for ensuring a successful application of sealants, as it emphasizes the importance of preparing the surface properly before applying any firestop products. Factors such as moisture presence, dust, oil, or improper surface textures can all contribute to substrate-related issues, underscoring the necessity to assess and prepare surfaces diligently.