We’ve discussed in some detail the benefits and function of prestressed concrete. However, we’ve yet to do a deeper dive into a related question: How is prestressed concrete made?
Prestressing concrete improves concrete’s tensile strength, which measures the ability of concrete to withstand being pulled apart. When tensile strength improves, concrete can be subjected to tremendous pressures before stretching or breaking.
Concrete is relatively weak when it comes to tensile strength. In order to counteract this inherent weakness, concrete producers typically use rebar and reinforcing mesh.
Prestressed concrete utilizes tensioned steel tendons, also known as strand, along with cables, rods, and wires. The tendons may be inside the concrete forms (internal prestressing) or outside (external prestressing).
The steel reinforcement is stretched to meet rigorous engineering specifications before concrete is cast over the stretched tendons. Sometimes, concrete is poured before tension is applied; this is known as post-tensioning.
Prestressed Concrete Production
Precast concrete production is therefore the creation of permanent stresses within the concrete itself in order to improve its strength and durability.
This improvement in tensile strength combined with concrete’s already high compressive strength (able to withstand compression — i.e, pressures from above and below) makes for a building product of tremendous structural integrity.
As the Portland Cement Association (PCA) explains, “Prestressing removes a number of design limitations conventional concrete places on span and load and permits the building of roofs, floors, bridges, and walls with longer unsupported spans. This allows architects and engineers to design and build lighter and shallower concrete structures without sacrificing strength.”
Design improvements and production efficiencies continue to assist in the manufacture of concrete structures that improve upon the load-bearing capacity of previous generations of materials.
Questions? Let us know! At Rogue Valley Precast, we’re ready to work, and we look forward to speaking with you. We are the premier precast concrete manufacturer in Southern Oregon, serving all of the Pacific Northwest and Northern California.