There are loads of advantages to using prestressed (or pre-tensioned) concrete for a construction project, but four of the advantages stand out above the others.
Prestressed Concrete Advantages
First, prestressed concrete allows for longer spans, so-called mega buildings, and bridges. These structures, large spans, and other concrete elements require high-strength concrete that resists tensile stresses. (More on this below.)
Second, prestressed concrete helps limit and minimize cracking. Reinforced concrete thus limits maintenance costs with high-tensile steel transforming into high-tensile strength for all types of concrete applications. Retaining structural integrity and remaining crack-free is obviously high on the list of concrete requirements.
Third, prestressing concrete permits construction projects to be completed using less concrete. This saves time, money, and limits environmental stresses related mostly to the transportation of materials.
And fourth, prestressing increases concrete’s strength, durability, and service life. Strong, durable, steel-reinforced concrete and high-tensile-strength steel beams (rebar) can last for decades. The dead load of a mega building itself is enough to warrant the introduction of prestressed concrete into design plans.
The four advantages are enough to offset any concerns about the relatively few disadvantages of prestressed concrete.
About Prestressed Concrete
Prestressed concrete is often compressed during production. Why? The answer to that question requires a brief examination of concrete’s tensile strength and compressive strength.
Compression is stress that’s placed on concrete from above and below. Concrete is renowned for its inherent compressive strength.
Tensile strength, on the other hand, refers to concrete’s resistance to forces applied laterally; in other words, forces that can pull concrete apart. Concrete scores relatively in measurements of tensile strength.
Thus, in order to increase concrete’s tensile strength, manufacturers will prestress the concrete forms. This is typically done with rebar or reinforcing mesh. The rebar is fashioned from tensioned steel tendons (also known as strand), wires, cables, and rods.
Rebar is pulled to a high tension. Concrete is then cast over the rebar. Once the concrete hardens, the result is a high-tensile (prestressed) concrete that is increasingly resistant to tension.
In short, prestressed concrete improves concrete’s tensile strength. This combined with its already impressive compressive strength results in a concrete product that is durable and incredibly strong.
Keep in mind that concrete may also be post-tensioned. This process involves pouring the concrete prior to applying tension.
Producers have been prestressing concrete since at least the 19th century. It didn’t take long to recognize the advantages of prestressed concrete, including the four main ones we mentioned at the beginning of this piece.
Consider a comment from the Portland Cement Association (PCA): “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.”
Questions? Contact Columbia Precast Products today.