Concrete beams are used to make bridges and large buildings. While it's easy to pour and level concrete in a variety of slabs or spray it as a thick mixture to coat walls, it is not easy to shape it into beams. Concrete cannot hold much direct weight without cracking and buckling, so manufacturers who make concrete beams use a number of techniques to both form the beams and make sure they are strong enough to provide the necessary support for the construction project.
Precast beams contain normal concrete with thickening agents added. Workers pour the concrete into a beam and then allow it to cure. They then remove the beam from the mold and ship it to distribution centers and construction sites. This precasting method allows manufactures to create concrete beams for a variety of projects, but it is most useful when the project requires many beams of the same shape and size.
Prestressed beams are made with precast concrete too, but with one important addition. Manufacturers take a net of strong steel wires and string them along the mold where the worker will pour the concrete. Workers use machinary to stretch the steel wires until they are under stress, then pour the concrete. The tightened steel wires add extra strength and stability to the concrete, and they run parallel with the beam, providing greater vertical support.
Fiber Strengthened Beams
Fiber strengthened beams use extra compounds to give the concrete beams additional properties. Manufacturers use many types of fibers, but they prefer carbon, epoxy, Kevlar, e-glass and similar materials. Sometimes workers mix in the fibers beforehand and then allow them to cure with the concrete. Other processes use mats of the fiber stretched in the concrete to provide support. Sometimes manufacturers create concrete beams with precast slits and fill the slits in with a carbon plastic material for added stability.