New styles of masonry anchors are more advanced that the old lead and zinc anchors. These new kinds of anchors make the job of attaching something to a masonry or concrete wall much easier. These anchors work equally well in either masonry or concrete. The choice of which anchor to use has more to do with other considerations, such as load, ease of replacement, weight of the object being secured, and the tools available to install the anchors. Anchors come in a range of sizes and materials and are designed for hundreds of uses.
Types of Masonry Anchors
The three types of masonry anchors are mechanical, powder-actuated, and chemical. Chemical anchors are used mainly in bridge building. Installing power-actuated anchors may require a certification. Mechanical anchors are the most commonly used.
How Masonry Anchors Work
They can work by a couple of different methods. They can expand inside the hole and hang onto the concrete. They can also work by friction in the hole. The stability of an anchor is influenced by the masonry quality and the position of the anchor. When an anchor is put too close to the edge or too close together, the anchor can crack the concrete. Anchors should be more than 5 times the diameter of the anchor away from the edge. Anchors should be spaced 10 times the diameter away from each other.
When selecting the anchor, consider the load that it will carry. A shear load is when the weight exerts force parallel to the surface. A tensile load is when the force is perpendicular to the surface. It may not be a clear cut case, as there can be a combination load. An anchor for an object hanging down is an example of tensile load. An object hanging on the wall is a combination of both kinds of load.
A hammer drill with a masonry bit is the best tool to drill holes for the anchors. When drilling holes for the anchors, you must make them the exact width and depth. Sometimes you will need a special bit to do this correctly. Be sure to remove any debris from the drilled hole.
Four types of Anchors
The styles of anchors are concrete screws, hammer anchors, one-piece expansion anchors, and two-step expansion anchors that are used with standard screws. Two-step anchors have a fastener that goes into a bigger anchor so the holes have to be predrilled. They can be taken out and replaced and are not expensive. One-piece anchors are either the sleeve type or a wedge anchor. The one-step anchor cannot be taken out once installed. Hammer anchors are used for hanging a lightweight object and are hammered instead of screwed in. Concrete screws are used for lightweight objects as well. They resemble a screw, but the threads are made to bore into the masonry or concrete. They can easily be taken out and replaced.