5 Effective Ways to Bolt Concrete

It may be necessary to bolt concrete when securing a heavy piece of machinery to a concrete floor, building bridges, or when doing foundation repair. There are many other uses specific to the type of bolt. The type of bolt you should use can be determined by the load it will bear and how it can be installed.

1. Cast-in-Place Anchor Bolt

A common type of concrete bolt is the cast-in-place anchor. It is a threaded bolt that has the head of the bolt cast in a piece of concrete. The bolt threads protrude from the concrete, and a washer and nut can be used to hold whatever is being secured. Cast-in-place anchors come in different shapes: L-bolt, J-bolt, pigtail anchor with a 10 degree bend, or with a steel plate and hex nut. The anchor bolt has a strong hold because it is pre-cast, but it is tricky to steady in wet concrete. It is usually used to tie walls to the foundation to make buildings more earthquake proof.

2. Epoxy Bolt

An epoxy bolt is used in existing concrete. To install an epoxy bolt, a hole is drilled in the concrete, and the bolt is inserted along with an epoxy, which sets the bolt. Epoxy is actually stronger than the concrete it is set into. Epoxy bolts are ideal where there must be close spacing of the anchors or they must be placed close to an edge.

3. Grout Bonded Concrete Anchors

These kinds of anchors are installed into existing concrete. Instead of epoxy, a high strength grout is used to secure the bolt. Grout has a few advantages over epoxy. It will not break down under high heat and is easier to pump into the holes. It does take longer to set up, and it is not quite as strong a bond as the epoxy.

4. Wedge Bolt

A wedge bolt is also used in a hardened concrete floor. A hole is drilled in the concrete, and a wedge is inserted into the hole. Then, a bolt is inserted and screws into the wedge. The wedge tightens around the bolt, securing it.

5. Concrete Drop-In Anchor

A concrete drop-in anchor is a steel expansion shield that is tapered at the bottom and has a cone-shaped expander plug. To install them, a hole is drilled, and the anchor is driven into the hole until it is flush with the concrete. Then, a special setting tool is used to expand the anchor. This anchor is used in light to heavy duty applications.

Bolts must be spaced along the floor or wall to distribute the load that will be attached. Building codes normally dictate the spacing of the bolts. Anchor bolts are permanent once they are in place unless part of the concrete holding them is removed. This can be a problematic. For example, when moving heavy machinery in a factory, it may be difficult to reconfigure the bolts. There are many reasons to bolt concrete, and there are just as many different types of bolts available.