Mechanical Expansion Anchors
Expansion anchors can be used to describe the majority of concrete and masonry anchors. Anchors of this type are designed with an expansion mechanism that compresses against the base material.
The expansion mechanism may be a sleeve, slotted shell, slotted stud, or wedge assembly which is actuated by a tapered cone, tapered plug, nail, bolt, or screw depending upon the anchor style. The compression of the expansion mechanism against the wall of the drilled hole allows the anchor to transfer the load to the base material. Anchors which are expanded by tightening a bolt or nut are considered to be torque controlled while those that are actuated by driving a nail or plug are considered to be deformation controlled. A deformation controlled anchor can develop a higher initial compression force when compared to a torque controlled anchor. Compression anchors may also be pre-expanded and/or used in conjunction with a drive nail. The expansion mechanism on an anchor of this style is actuated as it is compressed during the driving operation into the anchor hole.