What is a bond breaker?

A bond breaker is indeed a material specifically designed to prevent bonding between concrete and another surface. This function is essential in various concrete applications, such as in joint construction and slab-on-grade projects, where it is critical to allow for movement and control cracking. By acting as a barrier, a bond breaker ensures that the concrete can expand and contract freely without adhering to the substrate, which is important for maintaining the integrity of the concrete over time.

The other options describe substances that have specific functions related to concrete, but they do not capture the primary purpose of a bond breaker. For instance, while some materials can help concrete set faster or improve its strength, those roles do not relate to preventing adhesion. Similarly, a sealant applied before pouring concrete serves a different purpose, as it is intended to protect surfaces rather than prevent bonding. Understanding the specific function of a bond breaker helps clarify its importance in concrete applications.