Fasteners must be strong enough to perform their task, must be the proper type for the particular application, and must give satisfactory service throughout the life of the building. Use of longer fasteners and/or deeper placement within concrete will result in more holding power. The deeper a fastener is set, the greater the amount of material that must be fractured to pull the fastener from the concrete. Similarly, holding power increases with increased fastener diameter. Tables available from fastener manufacturers show maximum pullout strengths and shear loads for different types and sizes of fasteners in concretes of various strengths. Safe loads are generally one-fourth to one-fifth of maximum holding power.
The properties of the concrete into which a fastener is installed greatly influence selection of the fastener. Whether concrete is solid or hollow, hard or soft, or a combination of these properties, needs to be considered. The type of aggregate used in the concrete also bears directly on the selection of fastener type and its installation. The condition and age of the concrete also play a part in the selection of fasteners. For example, driving powder-actuated fasteners into concrete that is less than three days old is not recommended. Fastening near an edge may demand a different choice of fastener than in confined concrete where no edges are encountered.
Potential problems associated with atmospheric corrosion are best overcome by using nonferrous metal fasteners. Corrosion protection or avoidance can be a major consideration, since frequently the concealed parts of the fastener are those subject to attack.