List the materials that can be used to fill floor joints. What should not be used?

• A. Epoxy resin
• B. Cementitious grout
• C. Silicone sealant
• D. Silicone compound & modified grout. Do not use caulk

Answer: (D)

In floor joints, the filler needs to seal against moisture while accommodating movement and withstanding traffic. Silicone compounds provide the elasticity needed to absorb slab movement without cracking the fill, and polymer-modified cementitious grout adds the strength and bonding required to actually fill the joint and resist wear. Importantly, caulk is not suitable for floor joints because it’s typically too soft and prone to degradation under traffic, leading to gaps and leaks. Epoxy resin and plain cementitious grout alone can be too rigid for moving joints, and silicone sealant alone may wear away in a floor‑traffic environment. So using a silicone compound together with modified grout gives a durable, flexible fill that handles movement and sealing, while avoiding caulk.