Concrete by itself has excellent compressive strength. However, it is lacking in tensile strength. Reinforcing gives tensile strength to concrete.
Concrete reinforcing comes in all shapes, sizes, and strengths. Primary reinforcing is usually in the form of a rod or bar.
It ranges in size from #2 (¼ inch diameter) up to #8 (1-inch diameter). Typically, in a vault, we use the #2 or #3 bar at all the stress points, near the seal joint, in the corners, and near the lifting lugs in the vault cover. Secondary reinforcing is usually in the form of welded wire or fiber. There are many sizes and types of both, so I won’t go into that.
Typically, we use a 2 ½ inch long structural fiber. The length is important because we want the fiber to wrap around the primary reinforcing and aggregate in the concrete. As the concrete is mixed thoroughly, the fiber creates a pattern in the mix. In our opinion, the primary reinforcing is to protect the burial vault from catastrophic failure. The secondary burial vault reinforcing is to help with the cracking, chipping, and everyday handling.
Learn more about Burial Vaults from Rex Vault here.