Parts and Pieces Explained on Concrete Anchor Bolts Parts and Pieces Explained on Concrete Anchor Bolts

There are many different types of concrete anchor bolts out there. However, to properly use these anchors, it is important to know how they work. The following will describe two different types of concrete anchor bolts and the parts they are composed of.

Cast-In-Place Anchors

Cast-in-place anchors are the stongest type of concrete anchor bolts. The simplest of these types of anchors are identical to regular bolts. These anchors consist of a hexagonal head and a threaded body. The difference is that these bolts are planted head first in wet concrete. Once the concrete dries, almost anything can be anchored to the threaded ends of these bolts that stick out. Over the years many different types of bolts have been developed for use as cast-in-place anchors: bolts with hooks, bent bolts, and circular eye hooks are just a few of the types that are used. These anchors are so strong that they are most often used to adhere heavy machinery to a foundation or to make the walls of a building more resistant to earthquakes. The downside of using cast-in-place bolts is that they must be installed while the concrete is still wet, and cannot be moved after it dries.

Wedge Anchors

Unlike cast-in-place anchors, wedge anchors are slightly complex. These anchor bolts are the most common type of concrete anchors because they can be used to attach materials to concrete that has already hardened. These anchors consist of three main parts: The wedge, the sleeve and the thread. Here is a description of each individual component and how it functions.

The Wedge

The wedge is where the head would be located on a regular bolt, the end opposite of the threaded side. It is shaped like a short broad cone, runs through the sleeve and connects to the thread. The wedge is the end of the concrete anchor that is first pushed into a hole drilled in concrete and, as such, is the part of the anchor that is set deepest into the substrate.

The Sleeve

The sleeve is a round hollow tube that is fitted over the thread and butts up against the wedge. The inside of the tube is smooth and not quite big enough to fit over the wedge. The outside of the sleeve will usually have a series of prongs protruding from it to catch the walls of the concrete hole. When the wedge is drawn up, it forces the sleeve to expand, driving the prongs on its exterior tightly against the sides of the concrete.

The Thread

There are two different kinds of threaded anchors: fully threaded and partially threaded. The thread is the screw-like portion of the anchor. A fully threaded anchor bolt has a screw-like feature that runs from one end all the way across the body to the head. A partially threaded anchor, on the other hand, only has a screw-like portion across part of the body; the rest of the anchor is smooth. Regardless of which type, a nut is fitted over the thread as it sticks up through the concrete. The nut is turned and when it cannot move down towards the wedge because it is hitting the concrete, the wedge will instead be drawn upwards towards the nut. This in turn expands the sleeve and firmly fastens the anchor bolt.

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