Anchor bolts are used to attach structures and fixtures to masonry. Light posts, bridge railings and hand rails are examples of items requiring anchor bolts to attach them securely to concrete slabs or floors. In addition, walls and stairs are permanently fastened to concrete slabs and other walls during construction, using various sizes of anchor bolts. Most anchor bolts are a minimum of 1/2-inch in diameter in order to provide adequate tensile strength.
J- and L-hook Bolts
J- and L-hook anchor bolts have a bend at one end to grab onto the concrete or masonry structure. These type of anchor bolts are normally cast-in-place---meaning they are inserted into the concrete as soon as it is poured. The concrete cures, and securing retains the bolts in place.
Headed bolts are also cast-in-place anchors. A large head at one end of the bolt holds the anchor bolt in place withing the concrete. The bolts are set in place into wet concrete. The threaded portion of the anchor bolt extends above the surface of the concrete for attaching a washer and nut.
For installation in existing concrete or masonry, wedge-type anchor bolts are used. A hole drilled into the concrete holds the wedge anchor bolt in position. A nut and flat-washer threads onto the opposite end of the bolt. As the nut is tightened, the wedge anchor pulls toward the nut, causing the wedge to spread inside the concrete hole and firmly set itself into place.